Today is the day I pull the 425 from my 77 Deville and start the rebuild! When it goes back in, I would like it with headers and dual exhaust. I just wonder if anyone knows of any clearance issues I may be faced with when the engine is put back in, and can anyone suggest a specific brand of headers? The engine is going to be a stock rebuild.
MTS carries headers for SOME Cadillac body styles but I'm not sure which ones.
Sanderson makes a Cadillac header.....whether or not it will work with your car, I don't know.
If you can find a big block Chevy (or any other make) header for your particular car, you can cut the flange off and weld the Caddy flanges to them.
Any particular reason for wanting headers? The gain is going to be minimal (over stock manifolds) on a stock motor. If it were me, I'd run the dual exhaust right off the manifolds.
No reason for wanting headers really... I just like em. All I really want is dual exhaust with a nice low rumble. If running dual exhaust from the stock manifolds will do that for me, then I may go that route. It'd save me a few hundred bucks!
The type of mufflers you use will have more to do with sound than headers will.
I was going to put headers on the 500 that's going in my truck but I didn't want to have to pay for them and I didn't want to deal with the rust problem either. I could go with a coated header and eliminate the rust, but that only drives the cost up even more.
I was planning on installing Hooker Headers #2455 $166, which are for the big-block chevy, and I purchased a header flange kit from Cadillac Motorsports Development for $70. This allows the BB Chevy headers to bolt to the Cadillac 425/472/500 engine heads. I could not get these to fit the tight engine bay of the 79, so I am looking into installing Sanden block hugger headers.
I've also heard the stock manifolds for 472/500s are quite restrictive, and I'd imagine the same goes for 425s. Interestingly enough, the author of that page paid $166 for headers and the same price for a 472 to use.
Those Hooker Headers (#2455) are for '64-'74 A/B and F body cars. There MAY be something that will fit his car a little better.
I believe the Sanderson headers are "straight dump" headers. They might work on the car IF there is not a crossmember behind the motor mounts. If there IS a crossmember behind the motor mounts, there could be a problem getting the pipes to the headers.
Still, if he is only looking for sound, there's no need to spend money on headers.
