flywheel problem? help???

I have a 231 even fire that i got to put into my cj5 to replace my 225. From all the reading that I have done the flywheel should bolt right up. I had the flywheel balanced and went to bolt it up but the holes do not line up. They are off about a half a bolt hole in two of the hole. At most i can get 5 out of 6 bolts to line up. Motor block cast number is 1261787 which puts it a 1978 RWD. The motor was a automatic. Dont have any other info on the donor car. Any help would be great, Im at a lost. Thanks in advance

 

I could be wrong, but I don't think an odd fire flywheel will work with an even fire crank. The flywheel balances the engine on an odd fire. I believe the even fire engines are internally balanced. The odd spacing on the odd fire flywheel is so it can only be bolted up to the crankshaft one way, thus maintaining its' balance.

 

Will I guess your both right.................Yes the early Flywheel will bolt up to a later 3.8 / 231 same register and bolt pattern.........of course if it was an automatic Transmission motor you have to put a pilot bushing in the 231 crank...........and Yes the 225 was externally balance and the 231 Internally balanced...........but believe it or not some of the heavy 225 flywheels were neutral or ( 0 ) balanced. In either case one should balance the flywheel to whatever application is being used..............On another note if you are using the early 225 Heavy Flywheel the need on a "Even Fire" 3.8 is really not necessary!

 

Im able to put the pilot bearing in no problem but the 6 hole will still not line up right no matter how many times i turn it to try to match the bolt pattern. so do I need to swallow the bullet and find a even fire 160 tooth flywheel or????? AA has one for just about three bills but dont want to order it and find out i have the same problem. where on the crank is the number located? thanks again

 

I've got a 1984 3.8 231 Buick sitting out in the shop that I just walked out there a few minutes ago and took my old "Heavy" 225 odd fire Flywheel and put it on the back of the motor and ran 6 of 6 bolts in??? This motor also started life as an automatic..........I also looked at 2 other late cranks for the 231 and all have the same pattern.....................
Can't answer that question.................are your threaded holes in your crank grouped like 2 , 2 & 2 at 120 degrees apart? This would be a noticable pattern away from the evenly spaced pattern? Seems there is some possibilty of some Symmetrical & Asymmetrical bolt patterns in some 231 cranks...........
On all of these cranks there are 8 holes but only 6 are threaded.

Picture might help............

 

ever have one of those things not go right the take a few days away it it goes right on, you guys are right. got it t bolt up today

 

Thanks again, now on to the next problem im sure

 

endeavor to persevere.