Which engine?

Have to do some V6 engine work. Have a complete 225 setup & 231 setup. Which one would be the best to use in a modified (4:88, OD, 33"tires, headers) CJ5 for mainly serious off-road use (Moab) with a small amount of pavement use? The other will be used mostly for street use in a completely stock CJ5 with 3:73 gears & 29" tires.

Thanks,
rocmoc n AZ/Mexico

 

In my option I would pick the 225 for off road. Heavier fly wheel for more momentum at low rpms. They are the same engine tho. I believe you can bore out the 225 block to 231. Could be wrong tho

 

I have to second the opinion on the 225, the heavier flywheel is a huge benefit off-road.

 

The 231 is 0.050" over from the 225 - same bore diameter as the Buick 350. I recall that 231 standard pistons will work, if you bore to that size. But I would not throw away the extra bore iron if the engine could be bored to 20 or 30 over. The CW says that you can bore a typical gray iron block 60 over without sonic testing, but I would be more comfortable with 20 or 30.

There are fellows here that know much more about the Buick V6s than I do. I would first ask - is the 231 odd fire or even fire? I had thought that the 231 odd fire has the same heavy flywheel as the odd fire 225 - both need smoothing out due to their uneven firing angles. Do you have a flywheel for either engine?

I recall there are other considerations like crank strength, valve train oiling, head design, maybe others. There is a book on hot rodding the V6s that likely covers this - http://www.amazon.com/V-6-Performance-Pat-Ganahl/dp/093147213X/ref=pd_sim_b_2 - can be had cheap used.

 

231's used the light flywheel regardless. You can use a 225 heavy flywheel on an oddfire 231 but needs balanced on an evenfire. For Moab type terrain I'd use the heavy flywheel regardless. Personally I'd use the 225 for the off road Jeep and 231 for the street driver.

 

Thanks everyone! After receiving input from this site & another, the 225 is going in the off-road CJ5.

rocmoc n AZ/Mexico