302-351W crank

[phattrav]

Will a 3.25" 302 crank fit a 351W? If so, what rod length would be used?

My goal is to de-stroke the 351. The reason if your wondering is that a longer rod will be more efficient and decreasing the stroke will lessen torque but cause it to reach it's peak RPM faster. I think the increased rod length will somewhat make up for the lose in torque and it should rap out faster. What do you think?

[3eggOmelet]

All of that is true, but makes for crappy driving in a truck. Do you want to have to run 4000RPM to haul a trailer?

[pud]

the rod journals on a 302 are significantly smaller than the 351w's 3" (2.9994") mains. However Im almost positive you can get custom bearings to space and shim in the crank. You could get the 3.25" crank, and some chevy rods with a 2.1 or 2.0" mains and offset grind the crank to 3.3" stroke and use a short compression (pin) height. I did the math on this once, I took the windsors 9.5" deck & 7" rods, leaving me with 2.5" for half stroke and compression height. With 3.3" stroke and 1.35" pin height you come to a zero deck, wich means it will work. Bore it out to 4.050" and you have a 340 with 7" rods...Top it off with AFR 185's. 165s for a lower power band. 205s/225s for +7500 rpm. Plus an advantage is you have some beefy bearings.

[n2o88]

I think you have a truck, put a 4.17" crank in it. 427ci in a 351 .030 over block, some afr 225's and you have the capability of a 650+hp truck on pump gas.. Your not building a high rpm roundy round motor.

[pud]

I agree, but thats not what he asked. For all you know he could be wanting to build a drag racing engine.

[pud]

Originally posted by phattrav
The reason if your wondering is that a longer rod will be more efficient and decreasing the stroke will lessen torque but cause it to reach it's peak RPM faster. I think the increased rod length will somewhat make up for the lose in torque and it should rap out faster. What do you think?

It will but instead of say either way before and after you have 250hp. The stock 351 will make 250 hp @ 4500rpm for an example. The destroked one would make that 250hp @ 6000 rpm. Those arent factual numbers just an example. It would be easier for the engine to rev up faster with longer rods, especially comparing the difference of 7" to stock 302 5.09"...thats a 1.91" difference, almost 2" practically doubling the rod/stroke ratio of the 302. It would rev smooth. Australians did this with the cleveland, thats where the 2v closed chamber C heads came from.
351c's also have the 2.311" rod journals as the windsor, you could use some windsor 5.956" rods in place of the C's 5.778" rods. That would require a 1.5" piston heigh for zero deck. I havent heard much but I read you can shave the forged pistons 0.1", a 302's piston height is 1.6"...shave the top and flycut valve releases and youll be rolling....damn I have an idea now.