351C lubrication system & lubricants

That may be because nearly 40 years after the 351C was introduced, mods to the oiling system are still being hotly debated as to whether they're worthwhile or not. Note that most were used only on very high rpm drag-race engines which have much different requirements than endurance or especially street engines.
For myself, the blown 351-Cs I've seen often involve rods from cylinders 1 & 2, so routing more oil to the back of the block would be counter-productive for them. If you do this, physically restrain the hose every 12" or so from front to back; a hot oil-carrying hose gets very soft and flexible, and is 'magnetically' attracted to header pipes, halfshafts etc. As anyone who ever owned a mid-60s British motorcycle with external oil lines, treat them like a heart-bypass hose! Also, use at least dash-8 (1/2" ID) hoses & fittings to minimize flow resistance. Finally, I wouldn't pull oil pressure off the front of the block (shown in the photo) as the info simply doesn't compare to anyone else's data since it comes directly from the pump and will be 15-30 psi higher than what one gets from the stock port in back of the block, after the bearings & lifters take their share.

When I did this Mod I had about 6K to 10K on my engine. I used a hardline with AN fittings. So I did not have to worry about "High Performance Rubber" or "High Performance Braided" line failing. If I can find a pic. I will post it.

Everything fails sooner or later. Just what hads the lowest failer rate????

I was thinking about trying this trick using a custom made length of hydraulic hose with swedged/crimped ends and matching steel fittings for the block connections.

That ought to the the pressure, heat and vibration, no?

Some guys swear by the "external oil line", they consider it a method for reducing the probability of rod bearing damage at high rpm that can be installed without tearing the motor apart. It boosts the sagging oil pressure in the right hand oil passage thereby increasing the amount of oil flowing to the 3 central main bearings and improving rod bearing lubrication, but it doesn't resolve the underlying issues. Cavitation within the right hand oil passage (caused by the tappets) is still there, its effects are merely diminished. Excessive oil leakage in the clearances between the tappets and tappet bores is not resolved either, the external hose serves to supply those leaks from a different direction. Finally there is no control of where the oil is flowing. For those reasons I consider the external oil line a temporary aid that can be installed without tearing the motor apart, but not a final solution.

Its best to understand the problem before attempting to fix it.

Design and Performance Issues

Every way in which the 351C design deviated from the design of the SBF was to make an improvement, with one exception ... the lubrication system. The SBF utilized three lubrication passages; oil was supplied to the crankshaft main bearings first via a dedicated passage, then at the rear of the block the oil supply was split into two additional passages to supply the two banks of tappets; this is referred to as a main priority system. To save money the 351C was designed with only two lubrication passages, one for each bank of tappets. Lubrication for the crankshaft’s 3 central main bearings was supplied by branches intersecting the same oil passage shared by the right hand bank of tappets.



Ford found it necessary to redesign the tappets installed in the 351C due to the large port in the wall of each tappet bore, a result of the way in which the tappet bores intersect the oil passages. Tappets designed for the SBF and 351W allowed too much oil to flow to the 351C valve train. When a 351C equipped with the "wrong" tappets is operated at higher rpm the rocker covers flood with oil while the oil pan is slowly pumped dry at the same time. Thus the 351C has compatibility issues with tappets having certain types of oil metering designs; this also illustrates the importance of limiting the amount of oil flowing to the 351C valve train.



Lubrication system pressure is supposed to be controlled by a relief valve built into the 351C oil pump. The setting of the relief valve is controlled by a spring intended by the designers to maintain 60 psi nominal hot oil pressure (50 psi minimum and 70 psi maximum) but the 351C has a propensity for low oil pressure. Hot oil pressure below 50 psi indicates an excessive amount of oil is flowing into various "leaks and clearances”, overtaxing the capacity of the oil pump. The 351C also has a propensity for bearing wear. The symptoms of insufficient lubrication are evident even in low mileage engines; those symptoms include ribbons of bearing material lying in the bottom of the oil pan, scoring on the bearings, bearings being polished, or bearings worn so much they are no longer silver in color but copper colored. Obviously the excessive amount of oil flowing into various "leaks and clearances" is not flowing to the rod bearings!

A member of the Clevelands Forever forum had this to say:

quote:

I worked as a Ford dealership mechanic for 14 years, starting back in 1970. I replaced many main and rod bearings in the 351C and 400M engines. Those cars and pickup trucks were driven on the street and probably by older drivers. They didn't even have high miles and the engines were lucky to see 4000 RPM's. The mains and rods would become so worn, the oil pressure warning light would flicker on when the engine was hot, during idle and low RPM's. These engines were known for their oiling problems.

Photo courtesy of danishcarnut (aka Heine Hansen)

The two basic design flaws of the lubrication system are:

(1) There's no control of where the oil is flowing nor is there control of how much oil is flowing.

• Main bearing lubrication does not have priority or first claim to the oil discharged from the oil pump
  
• An excessive amount of oil flowing to waste in the tappet clearances reduces the amount of oil available for lubricating the crankshaft
  
• An excessive amount of oil flowing to the valve train or the camshaft bearings also reduces the amount of oil available for lubricating the crankshaft

(2) The large ports in the walls of the tappet bores create three additional problems.

• The ports allows too much oil to flow to waste
  
• The ports create tappet compatibility issues, possibly allowing too much oil to flow to the valve train
  
• The ports allow cavitation resulting from the motion of the tappets to spread within the oil passages.

People are under the assumption 351C lubrication problems occur predominantly above 7000 rpm, but cavitation does not turn off and on like a light switch at a specific engine speed. Cavitation increases gradually, becoming more severe as the speed of the tappets increases; cavitation is therefore impacting the oil passages to a lesser degree at engine speeds below 7000 rpm. Cavitation simply increases to the point of causing rod bearing failure at some point beyond 7000 rpm. But any amount of cavitation in the right hand oil passage shall impede the flow of oil to the crankshaft's 3 center main bearings to some degree.

There are those who insist the lubrication system is "good enough" up to 6000 rpm. Yet even low-mileage engines equipped with factory camshafts were plagued by low oil pressure and worn bearings. High lift rate camshafts and typical high mileage tappet bore wear worsen the problems. The lubrication system’s performance also worsens as engine speed increases; the performance diminishes to the point of rod bearing failure at some point beyond 7000 rpm. The bearings for connecting rods #2 through #7 are affected, but the bearings for connecting rod #2 or connecting rod #7 are usually the first to fail. All of the lubrication system problems impact solid tappet motors and hydraulic tappet motors equally. The symptoms are the same regardless if the rev limit is 5000 rpm, 6000 rpm, 7000 rpm or higher; the symptoms merely worsen as rpm increases. The consensus has always been that any 351C being rebuilt for any kind of performance application (from mild to wild) needs some improvement to the lubrication system.

History behind modifying the lubrication system for solid tappet motors

The production oil pump is equipped with an oil pump spring rated for 50 to 70 psi. Ford's first "fix" for the lubrication system was introduced in 1972; it was a high pressure oil pump spring to boost the 351C oil pressure. Moroso still sells a similar spring. The spring is rated for 80 to 100 psi. The higher oil pressure did not resolve the problem however, connecting rod bearings were still under-lubricated. This is an important aspect to understand, it can't be repeated enough, high oil pressure does not guarantee the 351C rod bearings are receiving adequate oil. The high pressure oil pump spring was not the solution Ford had assumed it would be, evidenced by the fact that the search for a solution continued.

Dyno Don Nicholson and other Pro Stock racers began installing tappet bore bushings in their pro stock Clevelands as early as 1973. The bushings quickly became standard in NASCAR engines too because stock car racing teams were gradually running their motors at higher and higher speeds. Ford quietly introduced a kit for installing bushings in the tappet bores about 1974; the kit also included restrictions for the cam bearing oil passages. These two corrective measures superseded the high pressure oil pump spring, they were, and shall always be Ford's successful remedies for the 351C lubrication system. A tappet bore bushing installation kit is available today from Wydendorf Machine.



Ford never publicized the existence of the tappet bore bushing kit, it came on the scene after Ford had stopped publishing the OHO Parts Newsletter. The kit was sold "under the table" in an era when Ford was supposed to be out of racing and out of the performance parts business, therefore the existence of the kit was not well known to the general public.

Tappet bore bushings became the essential modification for solid tappet motors to prevent rod bearing damage. Some folks used Ford’s bushing kit even though it was very expensive, some folks manufactured their own tools for installing the bushings (by copying Ford's tools), others relied on a machine shop to install them. The four modifications listed below became common for solid tappet motors to prevent rod-bearing under-lubrication:

(1) The main bearing and rod bearing clearances were increased (see note below)
(2) Clevite 77 bearings were installed, which included fully grooved main bearings.
(3) Cam bearing oil passage restrictions were installed
(4) Tappet bore bushings were installed

Note: In case you are curious, the bearing clearances in common use were:

• Main bearing street: 0.0020" to 0.0025" (0.0008" to 0.0009" clearance per inch of main bearing journal diameter)
  
• Main bearing race: 0.0025" to 0.0030" (0.0009" to 0.0011" clearance per inch of main bearing journal diameter)
  
• Rod bearing street or race: 0.0025" to 0.0030" (0.0011" to 0.0013" clearance per inch of rod bearing journal diameter)

Hank Bechtloff (i.e. Hank the Crank) offered an elaborate lubrication manifold system for modifying the 351C lubrication system beginning 1974 that was promoted by Hot Rod Magazine every time they ran a story about the 351C. The gentleman who designed the lubrication manifold system informed me he designed the lubrication manifold because he was opposed to the installation of bushings in the tappet bores for fear they would restrict the amount of oil flowing in the right hand lubrication passage. What is not widely know is that the Hank the Crank 351C lubrication manifold didn’t work as designed in every application; some race teams using his lubrication manifold still experienced bearing failure. The gentleman who designed the lubrication manifold believed the failures stemmed from the fact the manifold's installation was too complicated and the system was re-engineered a few times in an attempt to resolve the installation problems. The Hank the Crank lubrication manifold developed a poor reputation, even the designer gave-up on it. The designer candidly informed me he resorted to making unspecified "internal" modifications to his personal 351C engines. The majority of racing teams standardized on use of tappet bore bushings in the 351C.

Installation of tappet bore bushings is still a standard step taken by old-time 351C mechanics, racers and enthusiasts even today.

Some folks connect the plugged oil passage near the oil filter with the oil pressure port at the rear of the engine block via an "external oil line"; this routes oil discharged from the oil pump directly into the rear of the right hand oil passage. It is a method for reducing the probability of rod bearing damage at high rpm which can be installed without tearing the motor apart. That is the main attraction of this modification. It does indeed boost the sagging oil pressure in the right hand oil passage caused by cavitation; therefore it increases the amount of oil flowing to the 3 central main bearings and improves rod bearing lubrication. Cavitation within the right hand oil passage (caused by the tappets) is still occurring however, its effects are merely diminished. Excessive oil leakage in the clearances between the tappets and tappet bores is not resolved either, in fact the external oil line may increase the amount of oil flowing to waste in the tappet clearances. Finally there is no control of where the oil is flowing nor how much oil is flowing. For those reasons the external oil line is at best a temporary measure for protecting the rod bearings, but it is not a permanent solution; it is not a replacement for tappet bore bushings.

History behind modifying the lubrication system for hydraulic tappet motors

Since the typical street performance motor with hydraulic tappets only revved up to 6500 rpm or less nobody believed they required tappet bore bushings. Tappet bore bushings were considered too expensive for a typical street engine project; it is true Ford's bushing kit was very expensive, and some machine shops charged a lot to install them too (that argument is not valid today however because the tappet bore bushing kit sold by Wydendorf Machine is reasonably priced). The general consensus was that any 351C being rebuilt for any kind of performance application (from mild to wild) needed some improvement to the lubrication system however to achieve 60 psi hot oil pressure, to control the amount oil flowing to the valve train, and to hopefully prevent rod bearing wear or damage. So Forty years ago there were two schools of thought regarding modifying the 351C lubrication system for hydraulic tappet street motors:

(1) One school of thought adhered to the advice given by Jack Roush in Hot Rod magazine (1973, 1976). Jack Roush recommended a standard volume oil pump, the Moroso high pressure oil pump spring and the Moroso cam bearing restriction kit including the 0.080" restrictor for the left hand oil passage. Bearing clearances were 0.0020" to 0.0025" for the main bearings and 0.0025" to 0.0030" for the rod bearings. TRW (Clevite) bearings were recommended, which meant the motor was equipped with fully grooved main bearings, because fully grooved main bearings were a standard feature of Clevite bearing kits for the 351C. The motor’s cold start oil pressure ran about 120 psi with the high pressure oil pump relief spring installed, enough to burst an oil filter canister if the driver inadvertently blipped the throttle when the oil was cold, as many guys found out the hard way. A Motorcraft high pressure oil filter # FL-1HP was needed if the high pressure spring was installed. Notice the only measure taken to control the amount of oil flowing to the valve train was the 0.080" restrictor for the left hand bank of tappets.

(2) The second school of thought utilized a high volume oil pump to boost oil pressure and to hopefully deliver more oil to the rod bearings which had the clearances increased to 0.0025" to 0.0030" (in conjunction with main bearing clearances increased to 0.0020" to 0.0025"). TRW (Clevite) bearings were again recommended, which meant the motor was equipped with fully grooved main bearings; the purpose of fully grooved main bearings is to supply more oil to the rod bearings by supplying oil to the rods through 360 degrees of crankshaft rotation. Installation of a high volume oil pump alone without taking any measures to control where the extra oil was flowing would also supply more oil to the camshaft bearings and the valve train. So to control the amount of oil flowing to the camshaft bearings the small restrictions from the Moroso cam bearing restriction kit were installed, and push rods having restrictions in the tips or thick wall 5/16” OD push rods with 0.072” passages through the middle were installed to control the amount of oil flowing to the valve train. In this way the extra oil supplied by the high volume oil pump was routed as best as possible to the rod bearings where the clearances had been increased. This lubrication scheme was mentioned in a Hot Rod magazine story about a 351C build-up by Ron Miller (1985).

Confusion

The lubrication system problems and their solutions should have been clearly stated and well publicized but Ford stopped publishing the OHO Parts Newsletter in early 1973, just as the solution was being discovered. Ford entered an era (1973 - 1982) when it was officially out of racing and out of the performance parts business. During that era information was spread word-of-mouth via the grass-roots network of Ford performance shops.

This issue was also confused by a couple of popular publications. Jack Roush claimed in print the only lubrication system preparation his shop performed on their Pro Stock motors was to install the Moroso cam bearing restriction kit and the Ford - Moroso high pressure oil pump spring (Hot Rod Magazine 1973, 1976). Those who raced Pro-Stock in that era roll their eyes at that claim. It should be obvious to you by now that it requires more than that to resolve the problems with the 351C lubrication system.

The Ford Performance book by Pat Ganahl (published in 1979) has been used as a Ford performance information source for decades. Its an admirable book in many ways, and a wonderful document any automotive author could be proud of. Its helped and informed a lot of people over the decades. In the Cleveland chapter the book mentioned the tappet bore bushings in some detail, but only in the context of pro-stock drag racing engines. In the miscellaneous section the book mentioned using a high volume oil pump, then immediately contradicts that recommendation noting Jack Roush recommends the standard volume pump and a high pressure oil pump spring. In the building tips section the book quoted the Pro Stock Pinto book (published by Ford in 1972) regarding the lubrication system, referring to it as an indirect factory information source. That quote states no modification is recommended other than a deep sump oil pan and the high pressure oil pump spring. Of course I've already explained that boosting oil pressure with the high pressure spring (introduced in 1972) didn't fix the lubrication system. In citing that quote from the Pro Stock Pinto book Pat Ganahl's book perpetuated old, ineffective, erroneous information. The book then contradicts that quote by recommending additional modifications including the Moroso oil passage restrictor kit, oil metering tappets, and oil restricting push rods. The subject is closed by recommending that the tappet bores are checked for wear, but doesn't mention how much wear is acceptable or what to do if wear is found. In other words, the book mentioned a little bit of everything, contradicted itself twice, but offered no concise guidance. The Ford Performance book has many fine qualities, but the guidance provided regarding the 351C lubrication system is not its best feature.

Concise Guidance

Improvements to the 351C lubrication system should focus upon correcting the design flaws rather than the symptoms. One corrective action would be to modify the lubrication system to better control where oil is flowing and to better control how much oil is flowing. We can both minimize the excessive amount of oil flowing to waste via the tappet clearances and limit the amount of oil flowing to the valve train by installing 16 tappet bore bushings. We can also limit the amount of oil flowing to the camshaft bearings by installing 5 cam bearing oil passage restrictors. If we allow oil to flow unrestricted to the crankshaft after making those modifications we are essentially giving lubrication of the crankshaft priority, i.e. we've succeeded in modifying the 351C lubrication system to behave as a main priority system. Thus modified there is plenty of oil volume even with the standard volume oil pump, the standard oil pump spring shall operate in the middle of its range and control oil pressure at about 60 psi in the manner it was originally intended to do, and the quantity of motor oil flowing to the crankshaft shall be substantially increased at all engine speeds, even low rpm!

The tappet bore bushings also correct the other design flaw; they eliminate the large ports in the walls of the tappet bores, metering oil to the tappets via small orifices instead. This isolates the oil passages from the motion of the tappets thus eliminating cavitation in the oil passages; this is another vital step in making it possible for oil to flow unimpeded to the central 3 main bearings. The tappet bore bushings also resolve tappet compatibility issues.

The reasonably priced do-it-yourself tappet bore bushing installation kit available from Wydendorf Machine (selling for $400 USD) makes all of this affordable and within the budgets of a large range of engine projects. Wydendorf Machine



Four decades ago only eight bushings were installed in the right hand tappet bores, but it is customary these days to install bushings in all sixteen tappet bores. The reasons for this are to insure consistent oil control at all sixteen valves, to perform optimally with hydraulic tappets, and to resolve 351C tappet compatibility issues. The tappet bore bushings remove the task of oil metering from the tappets or push rods, and they make the 351C more tolerant of which type of tappet is installed.

My preference is to drill the bushings with 0.060" (or 1/16") orifices for all hydraulic tappet applications, all street and sports car applications, and all road racing, circuit racing and endurance racing applications because once the bushings are pressed into the block the orifice size can't be changed. The 0.060" orifices are a good size for a general purpose or "do-it-all" type of engine set-up. I would suggest this size orifice for dirt track and street/strip applications too.

Four decades ago four restrictors were installed in the passages supplying oil to cam bearings #2 through #5, but it is customary these days to install restrictors in all five cam bearing oil passages. Experience has proven an oil passage restrictor for cam bearing #1 improves the performance of the lubrication system, therefore it is assumed the oil passage for cam bearing #1 diverts a significant amount of oil from the main oil passage which it intersects. Acquiring five camshaft bearing restrictors shall require purchasing two Moroso #22050 restrictor kits, because each kit only has four cam bearing restrictors. The restrictor for cam bearing #1 is installed in a different manner than the restrictors for the other four cam bearings; it must be installed more deeply within the cam bearing oil passage so that it restricts oil to the #1 cam bearing and not to the #1 main bearing. The large restrictors included in the Moroso kits are not used.

My thoughts for preparing a performance engine without tappet bore bushings

Any performance motor being assembled without tappet bore bushings should be set-up to achieve 60 psi hot oil pressure by 2000 rpm (as per Ford spec). Ideally this would be accomplished by reducing the amount of oil flowing to waste, and metering the amount of oil flowing to the valve train and camshaft bearings, thus (hopefully) allowing the factory oil pump equipped with the factory oil pressure spring to operate in the middle of its control range.

In reality you will not achieve that goal without the tappet bore bushings. But to proceed with the idea of building a "performance" motor without tappet bore bushings, here are four considerations:

(1) Tappet to tappet bore clearances: Leakage of motor oil in the tappet to tappet bore clearance impacts the 351C so severely that I wouldn't build a performance motor with tappet to tappet bore clearances greater than 0.0017", which was the nominal factory clearance of a new motor. Tappet clearance is a measurement often neglected by enthusiasts when rebuilding a motor, but with a 351C its a step that can't be ignored. To make these measurements you're going to need the tools for making some very precise measurements, down to 1/10,000 of an inch. It shall be critical to check the tappet bores for being out-of-round.

The factory tolerance for tappet to tappet bore clearance is 0.0007” to 0.0027", the nominal clearance therefore is 0.0017". The production specification for tappet OD is 0.8740” to 0.8745”. The production tolerance for the tappet bore ID is 0.8752” to 0.8767”. If a tappet with the minimum OD (0.8740”) is installed in a tappet bore with the largest allowable production ID (0.8767”) the clearance is 0.0027” which is greater than the clearance between the crankshaft bearing journals and the bearings! More oil would flow to this “leak” than would flow to the bearing journals! If a block has worn or egg shaped tappet bores the nominal clearances will be greater yet. If the tappet bores are out-of-round they will have to be corrected to minimize oil leakage in the tappet clearance and to achieve adequate oil pressure. Installation of tappet bore bushings is the best method for repairing worn tappet bores, but another possible method for repairing them would be to acquire a set of oversize tappets from a tappet manufacturer and then hand fit the tappet bores for 0.0007" clearance.

(2) Metering oil to the valve train: Anyone assembling a performance motor without tappet bore bushings must take alternative steps in order to meter the quantity of oil flowing to the valve train. Solid flat tappet engines accomplish this via the tappets. SEC/Johnson was the original manufacturer of the Boss 351 oil metering plate solid flat tappet. That tappet is available from Speed Pro under part number AT2000 and available from Crower Cams under part number 66915X980-16P. This tappet will meter oil to the valve train properly without any other aid. Do not use edge-orifice tappets. Solid roller tappets MUST use tappet bore bushings.

Metering oil to the valve train is accomplished in hydraulic tappet engines via the push rods. The oil metering of any hydraulic tappet (flat or roller) should be augmented by employing push rods with 0.040" restrictors in the tips or utilizing 5/16" OD push rods manufactured from 0.116" to 0.120" wall thickness tubing. The oil passage in the middle of those super-thick-wall 5/16" push rods is so small it serves as a good restriction to oil flow. The best hydraulic flat tappet for the 351C is Speed Pro's part number HT900 tappet which is manufactured by SEC/Johnson. The anti-pump-up version of that tappet is part number HT900R. The best hydraulic roller tappet is the Crane Cams tappet.

(3) Metering oil to the camshaft bearings: Oil flowing to the camshaft bearings must also be metered, therefore oil passage restrictions for all 5 camshaft bearings should be installed whether or not tappet bore bushings are installed.

(4) Which oil pump? Even after performing these steps some enthusiasts like to shim the standard oil pump spring with a 1/8" or 3/16" thick washer; because they've found it necessary to do so in order to achieve 60 psi hot oil pressure. Others opt to use a high volume oil pump for the same reason. I used to use the Moroso high pressure spring for this purpose, but I've changed my mind about using that spring. Theoretically the motor requires additional oil volume, the pressure is low because the capacity of the oil pump is being over-taxed. BUT there's no guarantee all that additional oil volume isn't going to go straight to waste in the tappet to tappet bore clearances and provide exactly zero benefit for the engine. Making the lubrication system truly work well (lubricate the crank bearings adequately) without tappet bore bushings is like banging your head against a wall.

The path to follow should be very obvious, or at least I believe it is. I do not understand the resistance the subject of tappet bore bushings receives. Installing them is not destructive to the engine, and thanks to Mr. Wydendorf's kit it can be done at home for a reasonable price. I've seen people spend more money on a set of valve covers! My best advice is to employ the tappet bore bushings and the standard pump. That allows the lubrication system to operate as the designers intended.

-G

Great input guys

Auwch... when I read about all of these tolerances, I start to feel bad, and like pulling the engine, just to check whether everything is put together the correct way... Mine got rebuild once, but now after reading all of the above, I worry...

quote:

As is the case with most OHV V8s, oil is routed to the 351C valve train via the lifters and push rods. With a Cleveland the flow of oil to the valve train must be limited because everything sent to the valve train impacts the pressure of the oil supply for the reciprocating assembly.

Valve covers with spray bars are to be avoid then I guess, unless for racing and in combination with a properly modified lubrication system?

quote:

Originally posted by Kid:
Valve covers with spray bars are to be avoid then I guess, unless for racing and in combination with a properly modified lubrication system?

That's a good summation. Valve covers with spray bars are for hanging on your garage wall.

-G

quote:

Originally posted by Cowboy from Hell:
Valve covers with spray bars are for hanging on your garage wall.

Do you think those would fit next to my pin-up posters and calender... :-/

I will add a few points George didn't touch in his very comprehensive oil system summary. First, do NOT believe anything your stock Pantera oil pressure gauge shows! I've seen many examples of this Italian gauge/U.S sender give only 50% of true oil pressure. They nearly always read low; treat the gauge as an idiot light that tells you only if the engine is running. Add a cheap mechanical gauge in back of the block if you really want to know what oil pressures a Pantera 351C delivers. Note also - the stock water temp gauge is just as INaccurate.

Next, if you do bush the lifter bores for their oiling benfits, you will find the engine can now run solid or hydraulic roller cams with no oil leaks above or below the lifter boss. The only 'trick' is to install the bushings slightly taller than stock height. About 0.060" of bushing above stock boss height eliminates all need for special 'reduced-base- circle' roller cams. With link-bar roller lifters, the bushing tops may need small clearance notches.

IMHO, valve cover spray bars have a place in high rpm engines with aftermarket (read, 'stiff') valve springs. Not for lubrication but for cooling; a single drag race run up above 6500 with triple valve springs and a completely dried-up valve cover (from running oil restrictors) will give you BLUE valve springs from hysterisis and friction. That color happens around 600F and indicates ruined springs! So if the ORR race series or lots and lots of open track events is in your future and you use lots of rpms, use spray bar valve covers. If not, hang 'em up. I don't personally use them.

Agreeing with George's summary, I will mention that I've been running a stock Melling oil pump with a remote oil filter and a remote Ford/Laminova oil cooler using dash-8 Aeroquip lines. Theoretically, remote oil accessories need more oil volume; I've not found this to be necessary. Our 351-C today delivers 65 psi above 3000 rpms and 15 psi at 1000 rpm idle, with 10W30 oil. I built this street engine in 1990- 50,000 miles ago; not easy miles, either....

FWIW, here's my pratical experience on two Clevelands. I guess that you could simplify by saying that the external oil line ensures more oil to the bearings at the cost of less to the valve train.

I had put the external oil line on both my Clevelands, proper braided lines though. After a long high speed trip through Germany I had a lifter collapse and a flat lobe on the cam. So my conclusion was that the external line had decreased oil flow to the valvetrain too much, and I've now removed the external line on both my Clevelands. (and put in a new cam and lifters)

I know this is nowhere hear scientific fact, but I think that if your Cleveland is close to original power levels, you don't need the external line, and it may in fact hurt/wear your valve train

George,

With a 351C and 351W hyd flat lifter side by side, is there any notable difference between the two? Do you have any pictures you could post?

Thanks,

Dan

There's no external difference between the Cleveland and Windsor hydraulic flat tappets. Ford did make internal changes to the 4V Cleveland tappets to meter less oil to the valve train. But the aftermarket is going to be all over the spectrum in that regard. For instance Lunati manufactures a tappet they claim meters less oil, but the question is "less than what?". The only way I can advise anyone with confidence is to recommend push rods with 0.040" orifices in the tips or lifter bore bushings. I know those things work.

Merging Threads ...

quote:

Originally posted by bdud:

I have been looking at what is considered a good oil and I found this "independent test report". Motor Oil Wear Protection

I am not sure I fully believe that this test is all you need to worry about for oil, i.e. Mobil 1 0W30 racing is ranked 93rd and in the modest section. He did make what I think are some interesting observations..

quote:

Quoting 540 Rat blog:

"The old rule of thumb that we should have at least 10 psi for every 1,000 rpm is perfectly fine. Running thicker oil to achieve more pressure than that, will simply reduce oil flow for no good reason. It is best to run the thinnest oil we can, that will still maintain at least the rule of thumb oil pressure. And one of the benefits of running a high volume oil pump, is that it will allow us to enjoy all the benefits of running thinner oil, while still maintaining sufficient oil pressure. A high volume oil pump/thinner oil combo is preferred over running a standard volume oil pump/thicker oil combo. Because oil “flow” is our goal for ideal oiling, NOT simply high oil pressure."

"With the exception of high rpm hydraulic lifter engines, almost no engine should ever need to run oil thicker than a multi-viscosity 30 weight. The lower the first number cold viscosity rating, the better the cold flow. For example, 0W30 flows WAY better cold than 20W50. And 0W30 flows WAY better cold than straight 30wt, which is horrible for cold start-up flow and should be avoided at all cost. And the lower the second number hot viscosity rating, the better the hot flow. For example, 0W30 flows WAY better hot than 20W50."

I also spoke to Royal Purple & Joe Gibbs to get more information about oil for my engine. They basically said the same thing. Running less than 0.025 clearance for main and rod bearings use a 10W30 oil, >0.025" use 10W40. A stock / non-rebuilt engine might have to use a 15-20W50 oil. You might need to look at different qualities for flat cam followers. Then there is the debate on oil filters....

quote:

For example, 0W30 flows WAY better cold than 20W50. And 0W30 flows WAY better cold than straight 30wt, which is horrible for cold start-up flow and should be avoided at all cost. And the lower the second number hot viscosity rating, the better the hot flow. For example, 0W30 flows WAY better hot than 20W50."

My 6th grade daughter just did a Science Fair Project evaluating the viscosity of oils over temperature, and the data matches the comments above. Her data and methods are posted here for your reference.

Rocky

Test Setup #1 (I helped invent the "Viscometer")

Oil Under Test. The "Viscometer" forces oil through a controlled metering hole in the center of precision-fit pair of wipers.

This test was performed at ambient.

Relative viscosity was measured by precisely timing the descent of the "viscometer".

Results and Conclusion:

#1 Conclusion - I am pretty proud of her.

Results

Valvoline SAE 30 at -6.2°C took 49.6 seconds on trial one. After five trials it averaged at 41 seconds. At room temperature SAE 30 averaged 5.8 seconds. When we heated it up to 75°C the first trial was 1.7 seconds. The five trials at hot averaged as 1.8 seconds. With Valvoline 5W 30 at -1.5°C the five cold trials averaged as 24.2 seconds. When we tested it at room temperature it averaged at 4.3 seconds. At 72°C the first trial was 2 seconds and the five trials at room temperature averaged at 1.8 seconds. When I used the used Valvoline 5W 30 at -3.7°C it averaged to 22.2 seconds. When I did it at room temperature I got 4.4 seconds as the average. The used 5W 30 averaged at 2.1 seconds at 75°C.


Conclusion

My hypothesis was proved true. I predicted that the 5W 30 would stay more consistent and the 5W 30 did. This happened because the viscometer fell at more consistent times in the 5W 30 oil then in any other oil. Factors that may have caused the outcome are that the was more constant with its viscosity. Also, the temperatures may have been lower or higher for the 5W 30. I could further test this project by testing different oil brands to determine which oil brand has the best 5W 30. Real world uses of this information say that if they live in a place where the climate changes a lot then they should use the 5W 30.

The info written by 540 Rat is very interesting thanks for sharing it Brian. Your daughter's science project is great Chuck! We're proud of her too!

540 Rat's information makes me wonder if that Prolong stuff might be the hot tip for breaking-in a flat tappet camshaft. Who's gonna be the first one on the block to try it?

According to 540 Rat both he and D.Vizard are of the opinion that ZDDP is old school and there are better anti-wear agents available now such as calcium petroleum sulfontate used by the "Oil Extreme" company. But as I read the article the high ranking of the products manufactured by the "Oil Extreme" company made me wonder if the information may have commercial intentions. For now I'd give the guy the benefit of the doubt.

I agree with 540 Rat's comment that wear protection is not the only criteria in selecting a motor oil, but its possibly the criteria most important to most people. Wear protection is top on my list, but I also like to know how well an oil resists turning into carbon, in order to keep the ring grooves clean over the long term. This prevents the rings from sticking in the grooves, prevents oil burning, and keeps the engine running strong. When I was a kid Castrol was the top oil in this area, so it was popular for use in air cooled motorcycle and automobile engines. I also like to know how well the detergent package performs because I like the insides of my engines to remain clean like the day they were manufactured.

Since you're searching for a motor oil I'd like to contribute what I know on the subject of viscosity. No doubt the benefits of low viscosity oil are that it flows into clearances better and maneuvers within oil passages better too. However, oil viscosity is directly connected to the precision of the clearances in an engine. The issues are the taper and concentricity of the bearing journals and the bearing saddles. The ultra-low viscosity oil has benefits, but one drawback of ultra-low viscosity oil is that it cannot tolerate imperfections as well as higher viscosity oil. When the 351C was manufactured the 0W/5W oils were not available, and I doubt the engines could have been manufactured with enough precision in the machining process to use such ultra-low viscosity oil anyway. The 351C was original specified to use 20W40. I would not use 0W/5W oil in a 351C unless it had been re-machined to the precision required to use such ultra-low viscosity oil.

The 351C equipped with the factory crank and factory weight rods has an issue with insufficient rod bearing lubrication which is why fully grooved main bearings have always been recommended for the 351C; the fully grooved main bearings insure the maximum possible amount of oil is flowing to the rod bearings. However, the ultra-low viscosity oils don't have the same coherent oil wedge as higher viscosity oil, which is why fully grooved main bearings have fallen out of fashion for performance motors. A fully grooved main bearing has the same effect on ultra-low viscosity oil as the tire tread grooves in a rain puddle, it will channel oil away from the clearance between the crankshaft main journal and the bearing. Therefore if you're going to use 0W/5W oil in a 351C, use 3/4 groove main bearings instead of fully grooved main bearings.

One final drawback in using 0W/5W ultra-low viscosity oil in the 351C is that significantly more oil shall flow to waste in the clearances between the tappets and the tappet bores.

In spite of these drawbacks 0W/5W oil can be utilized successfully in the 351C. The prerequisites for using ultra-low viscosity oil in the 351C is precision machine work and tappet bore bushings. Rod bearing lubrication is significantly enhanced by the tappet bore bushings, this makes up for the 3/4 groove main bearings; the bushings also significantly reduce the amount of oil flowing to waste in the tappet to tappet bore clearances. I know a guy racing successfully with that combination in his 351C race motor.



Notice in this picture of the 351C lubrication system that oil flowing from the front of the engine to the rear of the engine in the right hand oil passage must make 3 sharp 90 degree turns in the middle of the passage in order to flow to the 3 central main bearings. Low viscosity oil will negotiate those turns better than high viscosity oil, this "should" result in more oil supplied to the crankshaft bearings.



These graphs are designed around a 2.1" small block Chevy rod journal. Notice that a bearing clearance that is too small rapidly reduces the load bearing capability of the bearing, whereas a bearing clearance that is too large reduces the load bearing capability much more gradually. This why machining the bearing journals and the bearing saddles more precisely (less taper and better concentricity) does not necessarily mean its OK to use smaller bearing clearances. There is an ideal clearance in regards to optimizing a bearing's load capacity, but its better to have more clearance than optimum than it is to have less clearance than optimum.

Based on these graphs a clearance of 0.0010" per inch of rod journal diameter is about optimum in the small block Chevy. In the 351C equipped with the factory crank and factory weight rods it has been traditional to use a nominal clearance of 0.0012" per inch of rod journal diameter (0.0011" to 0.0013"), which is not extremely different. Keep in mind that the 351C rod bearings are a bit narrower than the small block Chevy rod bearings.

Also notice according to the graphs tighter clearances reduce oil flow and increase temperatures. When clearances are tightened-up, less oil flows into those clearances and therefore the bearings run hotter, because the oil not only lubricates, it cools the bearings as well. So while machining the journals and saddles more precisely is good, making the clearances tighter (smaller) must be approached with caution. If the clearances are tightened-up ultra-low viscosity oil becomes a necessity in terms of maximizing the amount of oil flowing into the bearing clearances, AND the use of synthetic oil becomes a necessity because of its superior resistance to break-down at high temperatures.

One last thing, notice that I've always qualified what I've written about the 351C by specifying the use of the factory crank and factory weight connecting rods. This is because the crankshaft material (iron verses steel), the finish of the journals, the counter-weighting, the balancing and even the effectiveness of the crankshaft damper all impact the crankshaft's needs in terms of main bearing clearances. The weight of the piston/rod assemblies and the drilling of the oil passages in the crankshaft also impacts the crankshaft's needs in terms of rod bearing clearances.

FYI I use 10W30 synthetic Valvoline VR1 (black bottle) in 6018's motor which is still using the 40 year old factory machining.

Was there ever an explanation why 20-50 was the recommended oil for the Boss351? Seems to me that would do more harm than good internally, not to mention be a distributor pin issue in the long run?

I can't imagine using it in thosee cold Michigan winters?

Very interesting Rocky.
I did not think oil would flow that bad at low temps. Of course you did not in anyway influence her choice of project?
George, fortunately I have a solid roller (non-needle roller) cam and lifter bushes, no restrictors in the passages but heavy spring pressures and an aggressive cam grind. I wanted to follow what Jim Kumtz, my engine builder, recommended for oil. He is one that experienced flat follower failures using some of the modern API certified oils and recommended the Joe Gibbs, Redline, Amsoil or Royal Purple high zinc blends. In a push he said I could use Mobil 1 10w30 if I really wanted, the API certified oils he said were xxxx. This is what started my search. There are many reports of early cam / engine failures and people switching to high zinc oils, would that have happened if they used any of the top 10 rated oils?
Certainly the zinc had to go from oil as it damaged catalytic converters.
Doug, I remember changing my parents car oil in the UK many years ago and used 20w50, maybe it was necessary because of 'loose' machining tolerances, maybe poorer materials for block - pistons - bearings etc or lower quality oil.
I had intended to use Castrol 15w50 Syntec, which would have been a poor choice, so I am glad did some research. I went with Joe Gibbs HR4 10w30 which rated as moderate in the report but recommended by Kuntz. Hopefully this will help keep the dreaded distributor split pin problem away as well.
As a side note, have a read of February 2014 Hotrod magazine about the 10,000rpm Nascar Chevy engine. I am more of a F1 guy but the technology interests me. "Oil serves new purposes, we are using oil to cool and dampen parts where back in the day it was only used for lubrication". "Oil fills the insides of the valve covers, completely submerging the valve springs. The crew must drain this oil before removing the valve covers". They take 6 gallons of oil though, it is dry sumped.

You should see the chart on the 90W gear oil.

At cold it took about 150 sec, and at hot it was very close to the 2 second viscosity level of the other oils.

George - I will sit down with my daughter and go over the oiling information as soon as she finishes watching "American Idol"... gag.

Rocky

quote:

Originally posted by Rocky:
You should see the chart on the 90W gear oil.

At cold it took about 150 sec, and at hot it was very close to the 2 second viscosity level of the other oils..

That is because gear oil and crankcase oil are on two different grade designation scales. SAE 90 gear oil is about equivalent to SAE 40 - 50 crankcase oil. Here is a link to a chart.

http://www.synlube.com/images/viscosity_table_2.jpg

quote:

SAE 90 gear oil is about equivalent to SAE 40 - 50 crankcase oil

My daughter will definately use this info in her poster board. It is also nice to know that the experimental results make sense!

Thanks, Dave!


Rocky

quote:

Originally posted by Rocky:

My daughter will definately use this info in her poster board. It is also nice to know that the experimental results make sense!

Thanks, Dave!

Rocky

As your budding tribologist becomes more versed in the science of Newtonian fluids, she may want to become familiar with "true" viscosity units of measure (SUS, cSt). SAE 10W-40 is not a viscosity. It is a label that defines the performance of a fluid that behaves like an SAE 10 at low temperature, and an SAE 40 at high temperature.

Each of these grades (10 and 40) has a viscosity index on how they perform at certain low and high temperatures, measured on a logarithmic scale.

More reading here:
http://www.engineeringtoolbox....viscosity-d_397.html

quote:

Originally posted by bdud:
"Oil serves new purposes, we are using oil to cool and dampen parts where back in the day it was only used for lubrication". "Oil fills the insides of the valve covers, completely submerging the valve springs. The crew must drain this oil before removing the valve covers". They take 6 gallons of oil though, it is dry sumped.

My information shows right or wrong, that when the 351c first came into use in NASCAR after the 429 Shotgun (Boss 429) was eliminated by the rules, that initially there was an issue with valve spring failure.

Granted there has been a drastic improvement of technology in valve springs which let them last at higher lifts, higher rpm's for seemingly forever.

It was the lack of valve spring technology which limited the 427 Fords at LeMans to 6,000rpm's in the GT40's.

I know in the 351C's one of the solutions was to cool the springs by submerging them in about 1-1/2" of oil. At least according to the Woods Brothers.

They told me that fixed the problem.

Solutions often cross from one team to another (stealing others good ideas) and where that idea originated (Ford or Chevy camp) really doesn't matter except to the historians.

I personally can tell you that the location of the oil drainback holes in my A3 Motorsport heads positively creates a reservoir of oil which keeps the base of the springs permanently submerged in oil. Roughly a quart between the two heads.

Something else that I haven't seen mentioned in about 35 or 40 years which some think is very significant, the original Ford Boss 302/351 valve covers had drip tabs that fastened with screws to the insides of the valve covers.

The Detomaso script covers do not. They seem to be fashioned from the original molds of the Boss covers?

Just the fact that the Ford engineers thought them important enough to include at extra effort on their parts, makes them significant to me too.

Just food for thought here.

Biggest problem with drip-fingers and baffles in OEM rocker covers is, nearly all interfere with more desirable full-roller rockers. Triple springs all rub each other to dampen their harmonics, and drying up the top-of-the-motor oil supply can quickly turn the valve springs blue.... which happens around 550F I think. 'Drying up the heads' with restrictors is an example of something that works in ultra-high-rpm drag racing but not on the street. Some WFO-Cleveland fans add pressurized lube-bars in their rocker covers that sprays on the springs. Short AN lines from a tee at the stock oil gauge supplies plenty of oil.

quote:

Originally posted by Bosswrench:
Biggest problem with drip-fingers and baffles in OEM rocker covers is, nearly all interfere with more desirable full-roller rockers. Triple springs all rub each other to dampen their harmonics, and drying up the top-of-the-motor oil supply can quickly turn the valve springs blue.... which happens around 550F I think. 'Drying up the heads' with restrictors is an example of something that works in ultra-high-rpm drag racing but not on the street. Some WFO-Cleveland fans add pressurized lube-bars in their rocker covers that sprays on the springs. Short AN lines from a tee at the stock oil gauge supplies plenty of oil.

The baffles need to be pinched together and welded in that position then they stay out of the way of aluminum roller rockers. The drip fingers can be trimmed in length.

The aluminum roller rockers are bulkier than the Comp Cams stainless for sure. The stainless rollers are smaller and offer more clearance.

I'm using the Ford Racing aluminum roller rockers with Detomaso covers. It's tight in there but they do clear. No cover gaskets. Just siliconed to the heads.

There's a little work involved in clearancing everything but it's very doable.
using double springs with dampeners so yes there is a little friction there. The oil bath is a good thing.

quote:

can quickly turn the valve springs blue.... which happens around 550F I think.

From my experience non-ferrous materials can start turning blue at around 400 degrees F. When we sweat parts together we try to keep the temps at or below 350 degrees F. Above 400 degrees you are tempering the parts and the metallurgical changes to the pieces can be destructive depending on the application.
Jeff