Modification of the Cleveland motor's lubrication system tends to be a source of confusion for owners. Since there are several people on the DTBB in various stages of planning for a motor rebuild, I thought providing some clear guidelines might be helpful at this time. So as I promised last week, here's my thoughts on the 351C lubrication system.

An "ideal" race engine lubrication system routes the full discharge of the oil pump through a passage that supplies pressurized oil exclusively to the main crankshaft bearings. Once the main bearings have been supplied with oil, the oil can then be directed to the valve gear; i.e. camshaft bearings, lifters, rocker arms, camshaft lobes, camshaft drive chain, valve springs (for cooling), valve stems and the distributor/oil pump drive gear. Much of this lubrication is in the form of "splash" lubrication, rather than pressurized lubrication. Somewhere downstream of the crankshaft main bearing oil passage, and preferably at the end of the furthest oil passage, a relief valve must be installed to control pressure and relieve excess flow back into the oil pan. There must also be adequate provision for the rapid draining of oil from the heads and lifter valley back into the oil pan, otherwise the pan would be pumped dry and the engine would loose lubrication. The lubrication system of Ford's 427 SOHC motor incorporates most of these features.

The design of the 351C lubrication system diverges from this ideal significantly in order to reduce the cost of manufacturing the motor. The relief valve is built into the oil pump discharge, therefore the full volume of oil pumped by the oil pump is not supplied to the engine block, a portion of it is diverted immediately back to the oil pan. The oil system pressure control is based upon the pressure where it is highest in the system, rather than at a point nearer the end of the oil system. The second way in which the 351C lubrication system diverges from an ideal "race engine" system is that the main crankshaft bearings do not receive an exclusive supply of pressurized oil. Oil to main bearings #2 through #5 is supplied from the right hand lifter galley and is shared with those 8 lifters, and then a portion of the oil supplied to each main bearing is diverted to the camshaft bearing above it. Main bearing #5 also serves as a junction for the passage supplying oil to the left hand lifter galley. The final way in which the 351C lubrication system diverges from an ideal "race engine" system is that provision for oil drain back from the heads into the oil pan is limited to two 7/16" ID passages per head, and the passages in the front of the engine are almost horizontal, in other words, oil drain back to the oil pan is inadequate for high oil flow (i.e. high rpm) operation.

Do not infer from what I have written that the 351C lubrication system is poorly engineered, for it operates fine within the parameters for which it was designed. For engines no more powerful than the Boss 351 (perhaps 370 bhp) and at engine speeds below 6300 rpm or so, the system operates just fine, NO modifications are necessary. Neither infer that the 351C lubrication system is inferior to other American OHV (push rod) V8 motors, for many of America's best loved muscle car engines have similar lubrication systems.

Those of you who have read the book Ford Performance, or perhaps any of several old Cleveland NASCAR engine articles from Hot Rod magazine, will be familiar with the modifications that were employed by NASCAR & pro level drag racing engine builders to allow their motors to survive at the top levels of high rpm racing. One method employed an oil header in the lifter valley (beneath the intake manifold) that fed bearing #2 through #4 directly through special drilled passages to those bearings, thereby separating oil feed to those bearings from the right hand lifter galley. A second method employed bushings installed in the right hand lifter bores. There is nothing unusual about the installation of bushings in the lifter bores, this is a normal blue printing procedure to bring the clearance between lifters & bores into tolerance (0.0007"). The unusual aspect of the bushings installed in the Cleveland's lifter bores was that they had a very small 0.060" orifice drilled in them to limit oil supply to the right hand lifters & valve train. The idea in this case was to divert more of the oil from the valve train and into the main bearing passages. Both of these modifications are for high rpm motors being operated at speeds of 8000 rpm or more, neither modification is needed for a street engine, not even at 7500 rpm. In fact, limiting oil to the lifters should never be considered with hydraulic lifters. One other point I wish to make is that the valve springs get very hot during operation, the higher the valve lift and the faster the engine speeds, the hotter the springs get. Since the springs are cooled by oil splash, oil should not be limited to the valve gear unless dyno testing is conducted in which the oil flowing to the valve train is modulated while valve spring temperatures are monitored. If you are not equipped to do this testing, forget about limiting oil supply to your valve train.

So, here are my Pantera lubrication system recommendations for 2 levels of Cleveland engine, the "cruiser" engine and the "performance" engine.

The "cruiser" engine produces no more than perhaps 370 bhp and has a reasonable red line of 6300 rpm or less. In reality, the owner rarely runs the engine hard enough to see over 5000 rpm. Perhaps an occasional blast while entering a freeway, that sort of thing. The car is never raced competitively. My recommendation is to change the oil and filter regularly, at least once per year regardless of the mileage. If the engine is freshly rebuilt use synthetic motor oil to prevent the build up of deposits in the piston ring grooves. If the engine has a lot of miles on it, use regular petroleum based motor oil. Oil color should never be allowed to get black; it should be dark brown or cleaner when it is drained. The oil should feel tacky when it is drained, it should never be allowed to get thin like water. On an older motor the changes should occur every 3000 miles or sooner. Motors that have been rebuilt recently can stretch the oil change intervals to 5000 miles. In either case the oil change intervals should be adjusted to remain within my parameters; i.e. at least once per year, never allowing the oil color to become black or the oil consistency to become watery.

My final recommendation for the cruiser motor is regarding the oil pan. If you like to corner, accelerate or stop at high G force levels, then a well baffled, high capacity oil pan like the Aviaid #55365 or the Armando #404 oil pan should be installed on your motor. Even the best designed lubrication system will loose pressure if the oil pump pick up is allowed to run dry. These oil pans also feature windage trays & scrapers which are other beneficial oil system features. Aeration of the motor oil is a major concern in racing engines; the windage tray & scraper assist in keeping the oil away from the crankshaft which a major source of aeration. As a side benefit, keeping the motor oil away from the crankshaft also frees up horsepower that would have been lost due to the friction between oil and crankshaft.

If you truly just cruise, and never intend to corner, accelerate or stop at high speeds, my recommendation is to run 6 quarts of oil in your oem "baffled" 351C oil pan. That's 5 quarts in the pan and one in the filter. If your oil pan isn't baffled, I'm sure one of the guys who have installed the Armando oil pan will sell you his baffled Ford pan for a few bucks. If you are curious why I recommend 6 quarts, it's because of the Cleveland’s marginal oil drain back capabilities. At high rpm it is possible to have 1.5 to 2 quarts of oil in each valve cover. Add the quart in the oil filter and you have possibly 5 quarts circulating in the engine and nothing in the pan! Although this is not likely to be a problem with a cruiser motor, an extra quart of oil is cheap insurance.

Moving on to the "performance" engine, it is an engine that has been modified by the owner to produce 400 bhp or more, and the red line is most likely set somewhere between 6500 and 7500 rpm. The car is to be driven hard on occasions and/or raced competitively. I also expect the car will be subjected to high speed cornering, braking and accelerating; why else spend the money on such a powerful motor? Therefore the high capacity, baffled oil pan recommended for the cruiser motor becomes mandatory for this motor. The oil and filter change recommendations made regarding the cruiser motor apply here as well, except I expect you to run synthetic oil in your motor if your are racing your car competitively for the improved high temperature and superior anti-scuff qualities of synthetic oil. If you are racing your motor competitively, I also highly recommend that you cut your used oil filters open and inspect the contents as a regular diagnostic procedure during oil & filter changes.

From the perspective of the oil pump, the oil passages and clearances of the engine block behave as a singular restriction in limiting how much oil it can pump; to pump more oil through this restriction requires more pressure, and the oil system pressure is set by the relief valve built into the pump. The effect of a high volume oil pump is to pump more oil for a given engine rpm, however the high volume oil pump can not pump more oil through the engine than allowed by the pressure set by the relief spring. So if the relief spring of a high volume oil pump is set at 60 psi, it will not pump any additional oil through the engine block than a standard volume oil pump with a 60 psi relief spring. The additional oil pumped by the high volume oil pump will instead be bypassed through the relief valve back into the oil pan, in this situation the increased capacity of the oil pump will serve only to increase the aeration of the oil, which is an condition to be avoided. The only reason to run the high volume oil pump (Melling #M-84AHV) is if your motor has larger than normal main & rod bearing clearances, if your oil system is supplying oil to an external device such as a turbocharger OR if your motor has an external oil cooler plumbed into the lubrication system. If none of these conditions apply to your motor, the standard volume oil pump will be sufficient (Melling #M-84A). If the additional oil volume is not required, then the high volume oil pump will only serve to increase the aeration of the motor oil, which should be avoided in every way possible. Regardless of which pump is employed, a high pressure relief spring is recommended (Moroso #22850) to circulate more oil through the oil system and bypass less into the oil pan. To drive the pump which is now pumping against a 90 psi back pressure, a heavy duty oil pump drive shaft is recommended (Milodon # 22565). Since the heavy duty shaft will not twist like the oem shaft when the pump passes debris, the roll pin that secures the distributor drive gear on the distributor shaft has a greater tendency to shear. Therefore when the heavy duty oil pump drive shaft is installed it is very important that a second roll pin is installed in the distributor drive gear to prevent the shearing of the roll pin. One last component of this modification is the Fram HP-1 oil filter. The can of this oil filter has a 500 psi burst rating, this high burst rating is necessary when running the 90 psi relief spring because standard oil filters have been known to burst when used with the high pressure relief spring, especially when the oil is cold.

Now that you have modified the oil pump and related parts to pump more oil through the lubrication system, it is time to focus your attention to modifications to the short block that direct the oil to the main bearings where the oil is needed, otherwise there is no guarantee that any modification to increase oil supply will be successful; the oil may just flow through the "leaks" in the system and never reach the bearings. The first modification is very familiar to 351C owners, the installation of oil restrictors to cam bearings #2 through #5 found in the oil restrictor kit from Moroso, part number 22050. There is also a large restrictor in the kit designed for installation at main bearing #5 to restrict the oil to the left hand lifter galley, I strongly advise against installation of this restrictor for the reasons mentioned previously. The second modification is to "blue print" the clearance between the lifters and their bores, the ideal clearance being 0.0007". The lifters should not rock in their bores, they should fit snugly and only slide up or down with the application of force, they should not fall through the bores by gravity. The clearance is blue printed by the installation of bushings in the bores and then reaming them to size. This should be done to all 16 lifter bores, not just the 8 in the right hand lifter galley. By blue printing this clearance, you are minimizing the oil lost by leakage at the top and bottom of the lifter bores, this SIGNIFICANTLY improves oil feed to the main bearings. With this modification there is no longer a need to restrict oil feed to the lifters, because there is plenty of pressure and oil volume to feed the main bearings. Therefore the hole in the bushing that supplies oil to the lifter should be about 0.125" diameter. In the kit originally sold by Ford Motorsport, the bushings had an orifice only 0.060" in diameter because the intention was to restrict oil flow to the lifters and valve train. I am recommending use of the lifter bushings for an entirely different purpose, to correct for oil lost by leakage around the lifters in their bores.

Finally it is time to focus your attention to getting the oil to drain from the heads and back into the oil pan quickly. This is accomplished by insuring the existing oil drain back system is working to full capacity, by insuring the pressure in the valve covers and in the crankcase is equal and by the installation of additional oil drains if needed. Each cylinder head has 2 oil drain back holes, 7/16" ID. These holes mate with holes in the engine block. The holes in the rear of the block are also 7/16" ID and have a good steep angle to aid oil flow by gravity. The holes in the front of the block are only 3/8" ID; they should be drilled out to 7/16". These holes are nearly horizontal and need all the help they can get. You need to check that the holes in the heads and the holes in the block line up properly, and chamfer the holes in the block to correct any misalignment, then you need to check that the head gasket does not restrict the holes in any way. There is room in the lifter valley for 3 additional drain back holes; I recommend that the size of the existing holes is increased to 1/2" ID and that 3 additional 1/2" holes are drilled. With the lifter bore clearances blue printed the amount of oil collecting in the lifter valley shall be reduced, but the drain back holes serve to equalize the pressures in the valley and the crankcase. If you look down on the Cleveland cylinder heads you will find a depression in the head casting between the second and third push rod hole, counting inward from either end of the head. A 1/2" ID hole should be drilled in these depressions (2 holes per cylinder head), this will aid in equalizing the pressures in the lifter valley and above the cylinder head. These steps are all that can be done to optimize the 351C oil drain back system as it comes from Ford. If you plan to run continuously at high rpm, if you are using a high volume oil pump, or if you will be using you Pantera competitively, I recommend one further modification, the installation of additional oil drain back lines, 5/8" or 3/4", from the lower rear corner of each valve cover directly into the oil pan.

While on the subject of oil drain back, I want to point out that the oil drain back holes in the heads are located in such a way that a pool of oil collects in the lower side of the valve covers. This was intentional on the part of the Ford engineers. The pool of oil partially submerges the valve springs, thereby cooling them. Under no circumstances should you attempt to reduce this pooling of motor oil in the valve covers. If additional drain back lines are added to the valve covers they should be added high enough in the valve covers to maintain the level of the motor oil that pools up in them.

One final modification to improve the effectiveness of the lubrication system in motors used for competition is a vacuum pump to maintain a vacuum in the crankcase and thereby combat aeration of the oil. Some enthusiasts are under the impression this vacuum pump style evacuation system is employed much the same way the pcv system is employed on road going motors, this is not the case. The two systems have two different purposes.

The purpose of the pcv system is to vent the crankcase without allowing the combustion vapors in the crankcase to escape into the air. Pressure builds up in the crankcase due to blow by past the piston rings, the blow by consists of the spent gases of combustion. In an effort to reduce air pollution, while allowing the crankcase to vent, the crankcase is connected to the intake manifold so that crankcase vapor is constantly drawn into the intake manifold, and replaced by fresh, filtered air. This way air is flowing into the crankcase rather than vapors escaping into the atmosphere. This “positive” method of ventilating the crankcase is far more efficient at removal of blow by gases from the crankcase than the “draft tubes” that this system replaced. This efficient removal of blow by gases results in significantly less wear in the engine. For this reason the pcv system should be employed in all street going cars that have enough vacuum at idle to properly operate the pcv valve. The little pcv valve is closed by the high intake manifold vacuum at idle. If the camshaft installed in a motor is so “radical” that intake manifold vacuum is too low to close the pcv valve, then the valve cannot be employed because if the pcv valve fails to close at idle, it leans the idle mixture too much, and the motor will idle roughly or possibly not idle at all.

The crankcase vacuum pump used on competitive vehicles does indeed prevent pressure from building up inside the crankcase, but the vacuum pump maintains a higher vacuum inside the crankcase than the pcv system which operates at near atmospheric pressure. The higher vacuum of the vacuum pump system is intended to combat the aeration of the oil by drawing the air from the oil. Oil is aerated by the pumping action of the oil pump, and by the high speed rotation of the crankshaft. Aerated oil does not lubricate the highly loaded crankshaft journals as well as non aerated oil. Reduction of aeration is the main benefit of oil scrapers and windage trays installed in oil pans, the fact that they also result in increased horsepower is a welcome side benefit. Crankcase vacuum results in increased horsepower as well, as it helps the rings perform their task better, but again this is a side benefit, not the initial purpose. One must be cautious however when drawing a vacuum on the crankcase, because excessive vacuum will prevent the oil pump from pumping oil, the oem style wet sump pump will not tolerate much vacuum at all, the external multi stage pump employed with dry sumps will tolerate more vacuum in the crankcase.

Once your engine is assembled and installed in your Pantera, you'll need to keep an eye on the oil temperature and oil pressure gages when using your car competitively. If the oil temperature ever runs above 240 degrees F, you should install an oil cooler. If after installing the Aviaid or Armando oil pan, blue printing the lifter bores, modifying the oil pump for higher pressure and flow, and optimizing the oil drain back system you find your oil pressure still drops off during cornering, braking or accelerating, it will be time to consider adding an oil receiver system (Accusump) to your motor, or to install a dry sump lubrication system.

I’ll also point out at this time that if your motor oil requires an oil cooler, you can be sure the transmission oil is also in need of cooling, in the form of an electric circulating pump and an air to oil cooler.

Your slick friend on the DTBB, George

nice...

I don't think a dry sump makes sence with these engines. Even for racing.
1. the crank dosn't splash and 2, the baffled pan like you suggest should do the job if designed correctly even in high G corners.

Getting an oil cooler makes a lot of sense for sustained high RPM runs. I don't think peoeple realize if they do their first Silver State it will most likely be their last as the black sludge will emerge from the engine (cooked oil).

I love reading your posts. Very thurough and extremely informative.
THanks

quote:

Getting an oil cooler makes a lot of sense for sustained high RPM runs. I don't think people realize if they do their first Silver State it will most likely be their last as the black sludge will emerge from the engine (cooked oil).

I have been hesitant to do a SS due to the oil heat issue. However, I have been advised by those who have done them that if your choosen speed is no more than the 110mph - 120 mph range, a good stock engine should not need a cooler. The coolers of choice seem to be the water to oil units, but these of course require an upgraded water cooling system to handle the heat added from the oil cooler. And the high end (125mph and up) SS speed groups seem to not be successful using the street capable 2-pass Fluidyne units, but are finding a mondo NASCAR style unit fills the bill. Sort of the old ankle bone-to the-shin bone-to the- knee bone thing ;-)

Heavy cornering WILL starve the oil pump in a stock pan, even with the added quart (Ford advised doing this on the 351 BOSS Mustangs just for this reason). The Accusump would certainly initially provide a reserve oil source upon corner starvation but may not refill quickly enough to continue to perform adequately on a curvy, challenging track. Considering the plumbing and solenoid wiring needed to set up an Accusump (I have a two quart sitting on a garage shelf as a 'to do' project), you would probably find it easier to bolt on a baffled and trap doored Aviad, or one from Armando, 10 quart pan. This adds enough extra volume, and holds the oil nearer to the pickup, to prevent the drain back starvation issue. And the added volume will help a bit to keep oil temps lower, too.

Just my 2¢

Larry

thanks Larry, I see I wasn't clear there.

Let me clarify my recommendations. If you're running the Cleveland hard, you need the improved oilpan, period. I only recommend the stock pan for "cruiser" applications.

If after you install the Armando or Aviaid oil pan, improve the oil drain back system, blue print your lifter bores, etc; if at that point you still find your oil pressure dropping off in a corner or something, then you need to address the problem with the Accusump or a dry sump lubrication system. I would never recommend that you install the Accusump first, before making the other improvements.

your friend on the DTBB, George

VERY COOL article my friend. You should write for a car magazine, cause you know way more than those jokers do. Brock Yates is a dummy next to you.
Here is my bench racing question though. If you made a Cleveland motor that did have say a 7500 RPM redline, and say it had enough kawhonaas to actualy pull redline in top gear on level ground, and given standard stock gearing and tire diameter and aero and all that, how fast would you be going in top gear at redline???? 180 mph maybe??????????????????

De Tom:
I found a free tool on the Quaife site.
It's handy for answering such questions.
You can get it from http://www.ccunnington.freeuk.com/speedcalc.html

I used it to explore possible crown and 5th gear options.

On 275 55 tyres, standard ZF ratio I get:
Top Speed in 1 gear = 60.912 MPH
Top Speed in 2 gear = 92.403 MPH
Top Speed in 3 gear = 130.609 MPH
Top Speed in 4 gear = 160.559 MPH
Top Speed in 5 gear = 192.671 MPH

WOW!! Thanks Rapier. 192 MPH!!! That would be worth it. Just to know you COULD go that fast if the oppertunity ever presented itself. That is faster than a lot of Posches can go. Definetly be able to outrun 99.9 percent of the cop cars out there. That settles it, I gotta have an engine that will spin 7500 rpm!! It is now a mandatory requirement.

Only two points to remember... You can't hold that rpm for very long and you can't outrun radar!

Aw heck Rick. You sure know how to ruin a daydream. In real life I would never even consider trying to outrun our law enforcement officers. In fact I have my throttle cable jerry rigged right now so it will only go half throttle. I was just bench racing. I know I will never have enough money to do any of this fancy stuff anyway.