Hi
I have a 71 Jeepster Commando that I want to convert to diesel. It currently has a 231 buick in it and a TH400 three speed auto and a dana18 or 20 transfer case? I know that the 6.2 diesel will bolt to a th400, but will the extra torque tear my tanny out? I also think that the 6.2 is a little over kill for my little Jeep. I would like to use a 4 cyl Benz or Nissan, but don't want to get into too much adaptation.

 

I think you could bolt in a 4bt cummins from a GM stepvan (Frito Lay delivery trucks), as they bolt up to GM transmissions. You are way ahead of others who want to do this, already having the GM driveline installed. Should be quick and easy.

 

sorry to tell ya but your gonna need to change the transnission case as the buick and chevy have different bolt patterns.i'll make a suggestion but 99.9% of the people on here will say don't do it. but use an olds 5.7.that would pretty much bolt right in.use engine motor mounts from i believe a 98 olds and they will bolt right up.if you can find a running 5.7 pull the heads and replace the headgaskets and headbolts.and it should be good for quite some time.

 

Well. I learned something!! I didn't know there were different bolt patterns for TH400's.

Friend of mine has a 5.7 olds in his shed, waiting for a head gasket. We might try to tackle it together this summer. His was a really reliable car until the gasket went. He bought it new!

 

for gods sake replace the head bolts.where abouts you at in ia??

 

I was afraid of that....The Jeep TH400 is not just any old TH400,(shorter to make room for the tranfer case) so relacing it really isn't an option. The regular TH400s will not mount to the transfer case for the 4x4s, but you think this 5.7 will mount to my current tranny? How about the 4.3? Where do I find one? I guess I will start on ebay.

 

They make an adapter to mount a BOP tranny to a chevy motor. Summit racing part #TRD-0060. This should let you run a 4bt with your existing tranny.

 

if your jeep has a buick the olds will bolt up.a 4.3 would be a really nice choice,but the only place you will find them is in the rear wheel drive cutlass's.the front wheel drive cutlass ciera's have a different bolt pattern on the trans end.but one good thing about the rwd 4.3 is they came with cast iron heads,whereas the fwd 4.3 had aluminum heads to cut down on weight.i have a 4.3 in a celebrity wagon and it runs fantastic.it had a cracked alum head when i got it and i found a set of cast iron heads and it's been running great ever since,gets me upper 30's mpg's.there is a web site for the olds 5.7 diesels do a google for it,you might find somebody there that has a rwd 4.3.those rwd 4.3's are a rare bird.

 

So either one will fit? Probably not something I will find at the scrap yard either. Guess I have to start looking.

 

yes a 5.7 or a rwd 4.3 will work,the fwd 4.3 has a narrow bolt pattern on the back of the block to fit the fwd trans.also i believe the fwd 4.3 has no provision for motor mounts as it has a bracket on the front of the engine.

 

Looking at that adapter plate it says it will bolt any chevy, GM engine to a bpo trans. I looked up the th400 and I have read it can handle 285 hp engine. What does a stock 6.2 run? What smaller GM/chevy diesels are available besides the 4bt?

 

well i don't know where you got that 285 hp.my old chevelle was rated at 450 hp and the th400 worked just fine in it.and some of the mid 70's caddys with the 500's were pushing 570-580ft lbs of torque.so they can handle pretty much anything you can hook up to it.

 

I ment 295 hp.http://racetransmissions.com/store/p...products_id/40 glad to hear they can handle more than that, my biggest concern on this project is the tranny.

 

6.2 is out, it will never fit. I haven't measured it yet, but space is very limited.

 

Oh, it fits....it has been done! But at nearly twice the weight and half of the power of a mild gas 350 SBC, what is the point?