My block is already at +040 bored and worn a lot, so I'm looking for another one and I ask myself the question, two or four bolts main caps, is it so important?
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In my opinion it's not terribly important unless you have really big HP goals for the engine.
the extra bolts don't add a whole lot, if a motor is going to float the 2 bolt mains there isn't much 'window' until the 4 bolt mains start to dance around
a 2 bolt block with the fastener holes chamfered to prevent pulling material up and lifting the main caps off the block will hold more power than a 4 bolt block not prepped with chamfers. the outer bolt holes also remove material from the already sketchy bulkheads
guys get the line bore done but how many actually check the flatness of the block registers? after a couple rebuilds the registers can be out of wank, that's where stability begins, the area right around the bolt holes
a 2 bolt block with the fastener holes chamfered to prevent pulling material up and lifting the main caps off the block will hold more power than a 4 bolt block not prepped with chamfers. the outer bolt holes also remove material from the already sketchy bulkheads
guys get the line bore done but how many actually check the flatness of the block registers? after a couple rebuilds the registers can be out of wank, that's where stability begins, the area right around the bolt holes
A competent machine shop can drill and tap new mains, I know Moroso makes new caps. The more stable your reciprocating drive train, the longer your engine will live.
Agree with Chris, although the place to "stablilze" is with balance, precision components, and lightness.
I am sure Chris agrees, based on his precision built motor.
I am sure Chris agrees, based on his precision built motor.
I found a 4 bolts block but there is no more the main caps, do you know where it is possible to buy some ?
i'd pass on a block that's missing the caps, likely the caps are gone because there's something fatally wrong with the block. it's not as easy as just drilling the holes, if you're using factory caps they need to be fairly close to matching at the parting line or it'll take a lot of material to be removed to get there. to help get close before removing material from the parting line the shop has to remove material from one side of the cap and add it back on to the other shifting the bore in the cap over to match the other 1/2 of the bore in the block. yes they are off that far most of the time. all this can make a mess of the rear main & oil pan seal. top it off now you may need a special line bore timing set
is adding 4 bolt caps to an unknown block worth all this? HELL NO!
FWIW i bought a set of 4 bolt caps for $100, they came with the damaged block that i had sleeved & still don't know if it's fixed. to make matters worse i get the block back and the deck surfaces are totally fubar'd with drag mark gouges
hey, 4 bolt block for sale, 1 new sleeve & needs deck surfaces run / no returns!
is adding 4 bolt caps to an unknown block worth all this? HELL NO!
FWIW i bought a set of 4 bolt caps for $100, they came with the damaged block that i had sleeved & still don't know if it's fixed. to make matters worse i get the block back and the deck surfaces are totally fubar'd with drag mark gouges
hey, 4 bolt block for sale, 1 new sleeve & needs deck surfaces run / no returns!
A former super stock drag racer I know says the 2 bolt main caps are stable to about 8000 rpm. They are better than the cylinder walls and the lubrication system.
quote:Originally posted by George P:
A former super stock drag racer I know says the 2 bolt main caps are stable to about 8000 rpm. They are better than the cylinder walls and the lubrication system.
Exactly, if you want to build big HP start with big $ components. Maybe get one of those Tightass blocks.
I was convinced, but I do not know anymore why, that ALL the engines of ALL Pantera were 4 bolts, but a French "specialist" of the Pantera tells me that only the European GTS were all mounted with 4 bolts and that many "L" "were originally equipped with 2 bolts. Is he right?
No, not even close.
Only the De Tomaso vehicles equipped with US "engine code Q" engines had 4 bolt mains (these are the Cobra Jet engines). The Cobra Jet engines were produced in the US from mid-1971 through mid-1974. This would encompass all of the L models, and the earliest GTS and Group 3 models built while Ford was involved.
The earliest Panteras, such as the pushbutton models, were equipped with US "engine code M" engines, and the later Panteras built after the Ford era utilized engines sourced from Australia. These two versions of the 351C had 2 bolt mains.
The two bolt mains will hold the lower-end of the engine together long after the cylinder walls have given out. The cylinder walls are the engine's weakness, not the lower end.
Only the De Tomaso vehicles equipped with US "engine code Q" engines had 4 bolt mains (these are the Cobra Jet engines). The Cobra Jet engines were produced in the US from mid-1971 through mid-1974. This would encompass all of the L models, and the earliest GTS and Group 3 models built while Ford was involved.
The earliest Panteras, such as the pushbutton models, were equipped with US "engine code M" engines, and the later Panteras built after the Ford era utilized engines sourced from Australia. These two versions of the 351C had 2 bolt mains.
The two bolt mains will hold the lower-end of the engine together long after the cylinder walls have given out. The cylinder walls are the engine's weakness, not the lower end.
So a 1972 L had inevitably a 4 bolts.
I understood that it is not technically important, it is for the aspect "authentic" of the engine that I wanted to know.
In Europe the buyers of vintage cars are very attentive to the "authenticity", and even to the "matching number", I know that it is ridiculous but an engine not completely in conformity with that of origin can make lose a lot of value to a car.
It seems to me that in the US you are much more pragmatic and you're well right.
I understood that it is not technically important, it is for the aspect "authentic" of the engine that I wanted to know.
In Europe the buyers of vintage cars are very attentive to the "authenticity", and even to the "matching number", I know that it is ridiculous but an engine not completely in conformity with that of origin can make lose a lot of value to a car.
It seems to me that in the US you are much more pragmatic and you're well right.
4 bolt or 6 bolt architectures are much stronger than 2 bolt mains that were designed for non-hi performance applications. Longevity of your engine is dependent on a ridged block. Even if you are not racing or stressing the block at high R.P.M. the less deflection of the rotating assembly the better.
quote:Originally posted by George P:
The two bolt mains will hold the lower-end of the engine together long after the cylinder walls have given out. The cylinder walls are the engine's weakness, not the lower end.
Hi George,
I am trying to understand about the cylinder walls giving out. What is happening at that point? Can the block be corrected with a rebuild assuming that there is room to rebore the cylinders?
Thanks, Steve
When cylinder walls fail they crack through to the water jacket, and sometimes a big chunk of cylinder wall actually breaks away from the cylinder, leaving a big window exposing the water jacket. You can't use a dry cylinder liner to repair a cylinder damaged to this extent. There are such things as wet cylinder liners, but I have no experience with them, I don't know if they're worth a damn.
An engine limited to 6200 rpm, 8.0:1 dynamic compression, can get by with slipper skirt type pistons. But if a person wants to rev the engine higher and takes the cylinder wall weakness seriously they should do the following:
That's more or less what De Tomaso did to get the "early" group 4 race engines, based on the production block, to survive racing in the world endurance racing series (I don't know if they used longer rods, but their dynamic compression was closer to 7.6:1).
Most street engines are never stressed by operating a lengthy period of time at wide open throttle, even on the dyno they're never wound -out for more than a few minutes; so they can get away with higher compression, higher horsepower ... until the day the owner decides to take it to the track or wind it out across a empty desert road. Operating WFO means the engine is operating at maximum volumetric efficiency, and cylinder pressures are at their highest level. This is what stresses the cylinder walls.
An engine limited to 6200 rpm, 8.0:1 dynamic compression, can get by with slipper skirt type pistons. But if a person wants to rev the engine higher and takes the cylinder wall weakness seriously they should do the following:
- limit engine speed to 7200 rpm
- limit "dynamic compression" to no more than 8.0:1
- install round skirt pistons
- dynamically balance the reciprocating assembly
- consider installation of longer (351W) connecting rods (rod length to stroke ratio = 1.7:1)
- Limit horsepower to ~450 BHP (?)
That's more or less what De Tomaso did to get the "early" group 4 race engines, based on the production block, to survive racing in the world endurance racing series (I don't know if they used longer rods, but their dynamic compression was closer to 7.6:1).
Most street engines are never stressed by operating a lengthy period of time at wide open throttle, even on the dyno they're never wound -out for more than a few minutes; so they can get away with higher compression, higher horsepower ... until the day the owner decides to take it to the track or wind it out across a empty desert road. Operating WFO means the engine is operating at maximum volumetric efficiency, and cylinder pressures are at their highest level. This is what stresses the cylinder walls.
quote:Originally posted by George P:
When cylinder walls fail they crack through to the water jacket, and sometimes a big chunk of cylinder wall actually breaks away from the cylinder, leaving a big window exposing the water jacket.
Like that:
It's really ironic. On one hand the proponents of the Cleveland can't help about talking about the potential of a PRODUCTION engine performance wise, then proceed to list the RACING short comings VIRTUALLY as criminal?
The Cleveland isn't the only engine that when attempted to turn into a flat out race engine, flat out has problems staying together?
Both Chevys, sb and bb, and the 427 Fords, AMONGST OTHERS, all had (have) similar issues.
If you want to go Le Mans type racing with it, then for one thing, use a block intended for racing use. It's just common sense?
The Cleveland isn't the only engine that when attempted to turn into a flat out race engine, flat out has problems staying together?
Both Chevys, sb and bb, and the 427 Fords, AMONGST OTHERS, all had (have) similar issues.
If you want to go Le Mans type racing with it, then for one thing, use a block intended for racing use. It's just common sense?
It is indeed common sense and, although living in France, I do'nt envy to run the 24 heures du Mans with my Pantera, just cross the German border from time to time, I live near, to tease the Porsche and AMG on the highway sections where the speed is free 
As George pointed out, if you respect the redline of the engine and if you keep the compression modest, the engine will make even a club racer.
There isn't a lot of point in turning the engine rpm much more then 6,700 or 6,800 rpm in top gear. That is really where the power band shows.
By the same token, the 14 or 15:1 static compression Pro-stock drag racing engines of the day are very impractical also.
The four bolt caps are installed in these engines not for additional clamping of the crank, but to reduce or eliminate the flexing of the caps that happen under hard acceleration and deceleration.
The thrust bearing theoretically does that but as I remember, the clearance on that is set at .012". That's enough to create a vibration on the caps at certain rpm's.
Lots of things aren't necessary. Roll bars, seat belts, shoulder harnesses, etc. I'd rather have them then not.
Oh, the other thing that you want to avoid with the stock block is installing a steel crank vs. the iron crank and you want the biggest, ugliest balancer you can find for it.
Ford built the "Boss Balancer" for a reason. Why question it now?
There isn't a lot of point in turning the engine rpm much more then 6,700 or 6,800 rpm in top gear. That is really where the power band shows.
By the same token, the 14 or 15:1 static compression Pro-stock drag racing engines of the day are very impractical also.
The four bolt caps are installed in these engines not for additional clamping of the crank, but to reduce or eliminate the flexing of the caps that happen under hard acceleration and deceleration.
The thrust bearing theoretically does that but as I remember, the clearance on that is set at .012". That's enough to create a vibration on the caps at certain rpm's.
Lots of things aren't necessary. Roll bars, seat belts, shoulder harnesses, etc. I'd rather have them then not.
Oh, the other thing that you want to avoid with the stock block is installing a steel crank vs. the iron crank and you want the biggest, ugliest balancer you can find for it.
Ford built the "Boss Balancer" for a reason. Why question it now?
I have 3840 a euro type GTS from 1972.
Sold new to a gentleman in Turin Italy.
I have factory paperwork of an engine change under warranty by the factory, when the car had done 4K kilometres.
It had dropped number 4 valve destroying the engine.
Having had the engine out recently to change the rear main oil seal, I noted that the engine had 4 bolt main caps, also a bigger surprise was that this replacement engine had a 10 thou crankshaft grind????
was this a mustang type engine then??
Sold new to a gentleman in Turin Italy.
I have factory paperwork of an engine change under warranty by the factory, when the car had done 4K kilometres.
It had dropped number 4 valve destroying the engine.
Having had the engine out recently to change the rear main oil seal, I noted that the engine had 4 bolt main caps, also a bigger surprise was that this replacement engine had a 10 thou crankshaft grind????
was this a mustang type engine then??
I think it is what is called in Europe a "standard exchange" ie an engine rebuilt in the factory, not a new engine, it is common for the exchanges under warranty.
quote:
Originally posted by Peter Fenlon:
... was this a mustang type engine then??
Peter, all Panteras (excepting the Group 4 race cars) were equipped with Mustang engines. For the GTS De Tomaso replaced the Motorcraft carburetors with a Holley, slapped-on a high capacity oil pan, and replaced the "small" exhaust system with the GTS exhaust system (which was originally developed for the Group 4 cars); that was the 350 BHP engine. Seems your Panteras first engine didn't get too far before it dropped a valve head.
quote:
Originally posted by PanteraDoug:
... The Cleveland isn't the only engine ... has problems staying together ...
The guys without factory support or contacts, the guys racing on small budgets, the grass roots racers, and the amateur class racers WERE racing with production parts; they learned the limitations of those parts and learned how to make them survive. There was a big gap between what the professional teams were racing and what the amateurs were racing. That's just the way it was back then. Back in the era of the 1960s and 1970s you couldn't open a magazine and find affordable heavy duty blocks, cranks, etc advertised. Few people knew the heavy duty parts existed, and even if they did they couldn't afford them.
The typical professional level 351C racing engine in the 1970s consisted of a short block assembled completely from non-production parts. A heavy-duty racing block cast by Ford with thicker cylinder walls was available from contractors formerly associated with Ford’s racing programs (Bud Moore Engineering, Gapp and Roush, Holman and Moody, and Bill Stroppe). A fully counterweighted steel crankshaft manufactured by Moldex was available from the same contractors. Another fully counterweighted steel crankshaft manufactured by Hank the Crank (HTC) was available via the aftermarket. Chromoly connecting rods with doweled caps fastened by 7/16” cap screws and forged aluminum round skirt pistons were available from several aftermarket suppliers. If aftermarket rods weren't allowed, Ford had a set of heavy duty I-beam rods that were more unknown than the block and crank were. The engines were equipped with tappet bore bushings and lubricated via a dry sump style lubrication system when the rules allowed it. The only productions parts used on the engine were the cylinder heads.
The earliest blocks cast by Ford for NASCAR racing were cast and machined in the US. The block was usually referred to as “the 366 block", “Bud Moore's block” or “the SK block”. I believe the block has an SK number cast into it, SK56840. They had cylinder walls that were so thick there was no gap between adjacent cylinders in the water jacket (siamesed); they were made as thick as possible without inhibiting the flow of coolant through the water jacket. The thick cylinder walls allowed Bud Moore and others to bore the cylinders to 4.080" thereby achieving 366 cubic inches, which was the NASCAR limit for the smaller motors through 1973. The thick cylinder walls also allowed the engines to operate at high compression ratios and higher rpm (8500 rpm) without cracking cylinder walls. The bulkheads at mains #1 and #5 were thickened on their internal sides, but left "stock appearing" on their external sides; this gave the block the external appearance of a production block, they intentionally cast the block to hide its existence. It was intentionally hidden from the public and possibly even the NASCAR tech inspectors.
The general public was unaware of all this, they thought their professional racing heroes were racing with production parts.
There's also the fact that De Tomaso was a 'cad', there are documented instances of paying for performance parts, owners tearing inot engines to find them just stock.