A 231 is a 231 is a 231?

I've finally located a Buick 231 V6....An old fella up in the northland is telling me it came out of a jeep. However, he's unable, do to his health, get the casting numbers off the block to me. Can I safely assume it's the correct engine for my jeep....i.e. 90* Buick V6...either odd or even fire? I'd hate to drive hours and find it's not the correct vintage engine....And I don't want to let it get away if it's what I need to replace my shot Dauntless 225.


Thanks



Mike

 

Rebuild your 225. Wish I had instead of opting for the OF 231. 225 has higher compression than the 231.

 

Old CJ's never had 231's.

Unless this is your only vehicle, I agree. You know your 225 will fit.

***Useless Anecdote***

My buddy has a '79 Bronco. His 351m is junk. He found a 400 out of an LTD. For free.

I asked if he did a compression test. "No need," he tells me, "it has low miles and has been sitting for years."

He paints the block lime green (he's an '80's metal rocker guy), and is ready to install. Decides to change to oil and out pours a lot of water and a bit of oilish goo.

Teardown showed stuck rings on one cylinder and spun rod bearings on another. He now has the block at the machine shop being fitted for all new parts.

I have told him for years, "Buy the best, cry once".

Build the 225. They sound great, they run great, slap new stickers on it and go, " yeah, it's stock" after Bronco and Scout guys catch up to you.

 

Well, maybe I need to clarify things a bit..As it appears my reference to "correct" was interrupted from a historical perspective. I am aware the CJ5's V6 was a 225 V6.
However, I am considering the 231 V6 option because there are few 225 V6's available out there. None have been anywhere near me. I've got a WTB posted here...No response yet.

And I am not interested in going coast to coast in search of the "correct" 225 V6. Cause first and foremost, it costs time and money...And secondly, I've seen too many old used motors for sale that have been sitting for years and years in unknown condition etc. Or they're in the same sorry shape as my 225 V6....spun main and rod bearings, piston rusted in place....unable to be removed from the cylinder. Basically they all could use a overhaul top to bottom. Well, the machine shop quoted me $2,100 to do that kinda job. So, I searching for a replacement engine. Sure a 225 would be great...and a 231 would work just as well. This isn't a 100% accurate restoration I am doing here. Seeing as I've had no success finding a good 225 I am gonna take the first 225 OR 231 I find that's in reasonable running shape.

UPDATE: The guy was able to get the numbers off the engine for me..

He says this is what he found V6 F-23-4 1255862

Don't know what the F 23-4 indicates but it appears from the casting numbers in the tech section it's a 77 or 78 231...Could be an Odd-Fire, Straight Rod Pin Crank, with Integrated Dist. Drive OR an Even-Fire, Split Rod Pin Crank.

Anyone know why/how the casting number could indicate two different engine types?


Thanks


Mike

 

Because the mold used in the casting of the block is the same. Just the machining was different and they are very close. Records weren't kept quite as accurately during these times and they typically were in earlier years. At least that's been my experience.

 

If you end up w/ a OF 231, I have heard, and it was later suggested to me, to use flat top pistons rather than the stock dished piston. Someone else may be able to comment further on this but I truly feel my 231 feels a bit anemic compared to the original 225. Flat tops will increase the compression and perhaps help the anemic feeling I have. But, I am no pro engine guy or even really a novice. Just saying what I have experienced.