[olddog]

I was trying to come up with a longer rod 302, for a better rod ratio at high rpm. I’m not sure it is a good idea. Thought I would put it out as food for thought. The 302 1.7 rod ratio is not all that bad to begin with, but a 289 has a 1.8 rod ratio. We know race teams were spinning cast iron crank 289 to 8,000 rpm. I cannot say a longer rod would be better for high rpm, but it is typically assumed to be. This may be a rob Peter to pay Paul game, as the weight increase of the longer rod may increase the stresses more than the rod ratio improvement reduces them.

I calculated the piston pin compression height for a 347 stroker piston to be 1.090” by assuming the deck height clearance to be the same as a 302, which may or may not be true.

Now if you used the 347 stroker piston in a 302, it would allow a longer rod. A sb Chevy 400 rod is 5.565 long. That rod and piston combination would give a 0.051 deck height clearance compared to the 302 factory deck height clearance of 0.016 inch. Not ideal but perhaps a pop up piston would get a decent compression ratio. That would give a 1.855 rod ratio compared to a factory 302 rod ration of 1.7.