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Detroit Diesel 638 Engine Flywheel Cover

I was looking for the spec sheet of the 638 engine but could not find much info. I did however see a couple of pics of the engine.
I am always looking for alternative engines for the GMT400 series GM trucks, but, comparing the size of the engine in the pic. to the size of the starter, It appears the 638 would be much too big and much too heavy for the one ton pickups.
I believe the flywheel cover may also be the same as the bell housing adaptor, those items might also be interchangeable with adaptors from other Detroit engines.
I would start with a truck salvage yards in Your area and see what they might have that would work.
 
Hoo Boyyeah.
I was sort of searching the innernet for those engines. they seem to be a relatively rare item. There are some in ebay but I dont know if they had the bell housing on them.
A section of flat plate could be cut and drilled to match the back of the engine and the GM bell housing. A plas cutter would be mighty helpful for that operation, a computer fired plas cutter would be even better.
A section of card board could be used to do a pattern with.
The next problem would be if the trans input shaft would be long enough, it would depend how far out the back the cranking shaft flange extends compared to the GM configuration.
 
Ive done a couple adapter plates. Plasma is nicer, but I did one with a oxy/acc torch. Just drill the holes snd any tapping before torching. Actually I drilled the inset holes by fist drilling half way into it with rotor broach bits for od size, then progressively smaller leaving the centerpiece. Then drilled the center hole size. Then die grinder to remove the little material leftover. Then some backyard flame heating and oil bath to harden it up a bit. Time consuming but my labor cost less than paying someone! Haha.
 
I am sure you figured this out by now but i just saw this. Isn't that just a GM truck bell housing with the motor mounts on the rear? You might have to make a plate for the front but i would start with a late 90's truck flywheel cover. I am 90% sure it will bolt right on.

Your 638 Detroit is what was called a Package car repower package. Basically a crate diesel engine to convert gas UPS trucks with GM running gear to diesel. Everything from the flywheel back is 1999 era GMC. Clutch,pressure plate bellhousing and transmission.
 
blksmith said:
I am sure you figured this out by now but i just saw this. Isn't that just a GM truck bell housing with the motor mounts on the rear? You might have to make a plate for the front but i would start with a late 90's truck flywheel cover. I am 90% sure it will bolt right on.

Your 638 Detroit is what was called a Package car repower package. Basically a crate diesel engine to convert gas UPS trucks with GM running gear to diesel. Everything from the flywheel back is 1999 era GMC. Clutch,pressure plate bellhousing and transmission.
Click to expand...
I have found one on Amazon I'm looking at buy haven't ordered one yet.
 
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