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Old 08-17-2010, 01:30 AM
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Originally Posted by 471A
So far as I know, the best known early advocate of long rod engines was legendary engine builder Smokey Yunick. Smokey's reasoning tracks exactly what TopWrench explained that a longer rod yields a longer Dwell at the top of the stroke when compared to a shorter rod. Persuaded by Smokey years ago, I have for decades run long rods in a series of SBCs, both carbed and blown.
I have seen just as much evidence from both Reher & Morrison and Iskendarian Camshafts that it makes no difference in hp, if it does make a difference it is covering up a deficiencey in either head flow, incorrect camshaft spec, or intake restriction. Isky has a real nice set of charts and graphs showing piston position in the bore vs rod length at every degree of crank rotation and the longer dwell time theory is completely busted. It is such a tiny amount that differences in ring gap and oil ring drag have a bigger effect.

If you really get into searching this subject it is impossible to fine A-B-A testing of long versus short rods, Something else always gets changed at the same time so results are not verifiable.

Smokey was ahead of his time, but some of his theories have been passed by due to better methods of engine testing and computer modeling revealing things in the equation that Smokey didn't even know was there because he had no way to test or quantify it. It has been said today that head flow deficiencies in his day are what lead to his conclusions on long rods, there were no performance heads in his time, he was working with factory stuff like fuelie or 292 turbo heads(the precurser to Iron Bowtie) and we now know these can't be made big enough.

Just something for you guys to chew on, don't beleive everything the HotRod mags try to push down your throat.
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