: 1978 coupe deville... dropping in a 500

02-27-06, 10:44 PM
Hi there. I have a 78 coupe deville I just bought. Being an oldsmobile man, I have a question about interchanging the 425 (which has a blown rod) with a 500 that I can get that runs well. Is it a bolt in engine? I dont know whether or not the 425 is still a big block engine or not. Any info that will make this easier would be awesome... Thanks.

02-28-06, 01:58 AM
The 500/472/425/368 were all big block Cads. They're all just about interchangable externally. It should be just as easy to stick a 500 in there as opposed to sticking another 425 in there. As far as I remember the only thing is you'll need to cut a bolt down in order for the 500 manifolds to fit...

02-28-06, 09:58 AM
Yup, the only thing you'll need to modify, if you keep the passenger side exhaust manifold from the 500 is the front upper A-arm bolt. You will probably have to keep the oil pan and pickup tube from the 425 and mount them on the 500.

See my page here on this swap: http://www.mindspring.com/~dburden/engine_swap.html


The Ape Man
02-28-06, 06:01 PM
How about the oil pump housing?

03-01-06, 09:33 AM
I only had to use the oil pickup tube and bracket from the 368. I think the bracket is held on by one of the main bearing cap bolts. The oil pump stayed in the 500.


03-01-06, 09:59 PM
How about the oil pump housing?

When I did the swap of a 500 into a '78 Fleetwood and a 472 into my '79 Deville, I used the 425 oil pump because it angles down. That way the oil filter clears the fan shroud. I used a ported CMD Gold pump on my 472.