[Mr. P-Body]

ironhead,

"Safe" is a relative term. Compared to what? We rev our pump gas "street" engines with the Eagle (3") crank to about 6,600 regularly. Rick Holladay revs his 4" stroke 3.25" main 440 to 6,800. Scott Roberts revved his 406 to 6,600 with the hydraulic cam, and to 7,200 with the solid. The Drunken Injun (3" main) revs to 8,800. With the exception of "DI" (only 3 passes on it so not enough "hard" data), ALL of these engines are racing and driving for more than a year or two without refreshing.

RPM is more a function of head flow and valve train than it is "bottom end". You do, of course, need high quality parts in there. The "weak link" in a stock engine is the connecting rod. They gotta go! Rod bearing "speed" is another area that can use some attention. IMO, the only real drawback to the larger main journal, aside from the weaker block (NOT insignificant), is the added heat it puts "in" the oil. I would think that's only a big issue when high RPM is used for extended periods.

It is commonly believed a 455 crank is stronger than a 400. True enough. But again, measured against WHAT? The main journal in a BBC is 2 3/4". So is a Hemi. Those cranks are plenty tough, so the added 1/4" of diameter in a "large journal" Pontiac is not necessary. The crank in a 400, even a "stroker", is far stronger than the block.

Jim

[tom s]

come to think of it it was oil pressure required for main size to RPMs.Tom

[Me Notyou]

Originally Posted by Mr. P-Body

ironhead,


The "weak link" in a stock engine is the connecting rod. They gotta go! Rod bearing "speed" is another area that can use some attention. IMO, the only real drawback to the larger main journal, aside from the weaker block (NOT insignificant), is the added heat it puts "in" the oil. I would think that's only a big issue when high RPM is used for extended periods.


Jim

Has anybody had any success cutting down the rod journal on these cranks? What would be the benefits if any?

[OINK 1]

Factory 400 Nodular Cranks in my solid lifter motors 7400 rpm , That's the plain Jane motors.Crower rods USA Made , cost more $$
428 4 bolt's with Arma Steel cranks 7400 rpm Crower rods
455's With billet 4 bolt caps and arp studs, Nodular crank, roller cam, 7200 rpm.
Bill Miller Alum rods and Crower Super

Now that cast or forged China stuff, I don't know, but all the people who saved $$$
by not buying American made are coming home to roost.

We just took apart the Flying Piglet race car motor( Fast Eddy) the parting line of the rod bearings in the Eagle rods are showing copper. That means the rod forging is going out of round, now the arp( USA made) rod bolts were the only thing that kept it togther, 4.25 stroker motor. WE NEVER SAW THIS WITH AMERICAN MADE RODS !!! Think people, you are cutting your own throats !!

Pontiac Gregg