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.
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.
Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
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.