Why do some of the top manufacturers make 6.2 rods but crank manuf. don't list there cranks using 6.2 rods ? Callies is the only one that does'nt list rod length with there specs. What gives??? Do you need a tall deck block ?
The reason I ask is I have a line on some 6.2 billet Olivers--(real cheap)

 

Think about it...

The deck height on a stock SBC is 9.025", crank CL to deck. So, ½ theh strok, plus the rod length, plus the "cpmression height of the piston, plus the deck clearance, equals 9.025". It's pretty simple from there.

9.025" - .025" (deck clearance) - 6.2" (rod length) - 1.74" (350 stroke is 3.48", half of that) = 1.06". The pin is about 7/8" in diameter (I don't recall the exact number); so 1.06" - half of the pin diameter = .622". Into that space you must fit the thickness of the small end, plus the thickness of the piston top, plus some clearance. I don't think so. Also, the entire ring package would have to fit in 1.06", from the top of the piston to the center of the pin. The second ring would be over the pin bore as well as the oil ring.

Bottom line: you pretty much need a tall deck block to run those rods in a normal stroke 350 motor, let alone the sort of motor that would need a rod that long.

All of this has nothing whatsoever to do with the crank, except that it would be nice if the crank you use has big enough counterweights to balance the heavier rods, so you wouldn't have to use Mallory metal. Other than that, the crank does not care what length rods you use, once you get past 5.7" ones in a SBC.

 

thanks for the reply rb.
Oliver and Eagle are a couple that offer 6.2 rods. What kind of (crank-rod piston) combos are being used with these long rod lengths ?

 

I believe those would most likely be used in the "Rocket" (Olds racing) block, and Dart, and a few other tall deck blocks, which I think are .400" taller or some such. Basically you'd end up needing a piston that would be the same a 5.7" rod 4" stroke combo, in your choice of bore; I've built such a thing out of a stock 400 block so I know that it can be done, we used Lunati & Taylor pistons IIRC.

 

don't hold me to it rb but a SBC wrist pin is .96 or so, i'm too far from my garage to look it up for sure.