Quote:
Originally Posted by BruceWilkie
I think with 3.25 main it might be a good compromise to drop down to a 4" stroke(440 ci with 4.185 bore)... Still good torque and less strain on the block... generally happier at rpm than 4.21 or longer stroke. Stock rod length is fine but BBC big end allows better radius on the journal. IMO a factory 421 or 428 crank is plenty strong. I'd upgrade to better main caps and studs though. Some(Eagle, K1) offer a 6.635 BBC rod that MIGHT help acheive zero deck as its only .010" longer than stock... The 6.7 and 6.8 BBC rods arent a bad choice though... Some builders will use a 6.535 BBC rod BUT its likely the piston gets a bit heavy...
3" main blocks have 1/8" more "meat" wrapped around the crank. Dont sound like much but when you actually look at the difference you can see it.
Still regret lettin my 440 go with a car I sold... its a good combo even with iron heads.
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The 4 inch stroke crank in a 3.25 main in a 455 block should be fine, I ran one for 3 years in a dirt track car with no problems with cast rods and heavy TRW forged pistons. Ran it at 6000 RPM every lap. This was in the late 70s and there is a bunch of better parts now to let you lighten the reciprocating weight. A good oil pan and pump is going to be necessary for sure, factory pan is never going to get it done. Going to a shorter stroke will drop some of the bottom end that is a problem to hook up off of corners many times. Starting with a 455 block if you wanted to you could go .060 over making it a 446 cu. in. only 9 cubes less than a 455. An oil cooler and oil temp gauge will be help you keep it together. Accusump would also be a good addition.