225 Head Replacements... 231??

I just found out my heads are cracked. When speaking to the machinist he told me that heads for a 231 would also fit. I'm trying to find information on this to verify what he is claiming. There's some references to a fitment file but non are still active. im looking to see if anyone can help. so im clear i have a 225 block looking to see if 231 heads will fit.

Thank you in advance

 

They will physically bolt on, but the oiling is completely different.

The 225 has has a pressurized oil passage through the head to the rocker shaft that dribbles oil out to the rockers. A 231 has bleed holes in the top of the lifters that feed oil up to the head via hollow pushrods and a hole at the upper end of the rocker arm.

A 231 heads *might* work on a 225 if you use 231 lifters, pushrods, shafts, and rockers but I can't verify that. You would also need to make sure the oil passage in the block that feeds the heads is properly blocked off to maintain oil pressure.

 

As Fireball stated and you'd have to source odd fire 231 or first year low port even fire (78) heads. None of which are in great supply anymore.
225 parts are still fairly common and reasonable enough. Post a wtb here and browse FB marketplace 225's show up very reasonably quite often

 

ok fun times lol thank you for the information Fireball and confirmation Rich. I'll keep my eyes out for 225 heads.

 

Yeah, I have been drooling over that add myself.

Someone should drive up there, get the whole pile, pick out what they want to keep and haul the rest to a Jeep swap meet. Could probably come out good, or at least pay for the trip.

I sold two Buick V6 engines at the last Willys Fall Reunion. The odd fire engines are getting scarce too, and I prefer them to the later even fire version.

 

YES, you can do this and have a better oil system and water passages in the heads. We did this conversion about 5 times along with decking the heads a little and installing TA Performance's improved timing case cover that gives better oil pressure.....also bought the upgraded oil pump gears. Would install a hi flo water pump and thermostat too. Made a nice upgrade.

 

Interesting. I was wondering if it was possible. Good info!