I helped a my buddy swap his worn out 4.0 from his '87 cherokee to a reman Mopar 4.0 unit. Im pretty familiar with jeep straight 6's and have seen a lot of them. Once we pulled his motor out and it was on the hoist i noticed it had some wierd "BT" casting on it. Thought nothin of it and then looked at the 2 other renix era 4.0s that i have laying around. Its not on them. It is a fairly large casting of the letters "BT" in the side of the block. Its on both the driver and passenger side of it and is even in the end of the serial number in the side of it. I'd like to know what it means. Anybody know???

 

Oh, forgot to add that it is also cast into the bellhosing area behind the flywheel to the left of the rear freeze plug. The block also has a petcock drain in one of the block plugs seen in the one pic which i normally see on boat engines???

 

No ideas??

 

im dieing to know myself

 

The drain valve was probably added - I've been wanting to do the same thing myself.

The "BT" may be a revision or version designator - I don't know what else it may be yet. It's definitely an AMC mark - not the AMC logo in the second picture (RENIX blocks started changing from AMC casting to the MOPAR Pentastar in late 1988.)

That's my best guess.

 

It has been bugging me....

Ive spent an hour or two searching around the internet and came up with nothing. I searched around comanche club too.

The block drain would come in handy thats for sure.

 

another strange thing the two different size freeze plugs the little sign on the side means AMC american motors corporation

 

http://www.bulltear.com/forums/showt...asting-s-(AMC)

 

http://street2mud.com/webfiles/AMC%20Engine%20codes.pdf

 

Bump. still curious