I’ve done it about 5 x but all on 65-68 Mustangs. Never done it on a 74-78.Has anyone ever done this before?
That was my build. It works, there are a lot of pictures in my thread.I have seen someone do a build using 65 stock manifolds with 65 down pipes
My dad saw your thread and we both liked the work you did and planned on copying it. My main concern was the manifolds being restrictive. My engine is a 302 .30 over. It has a mild cam. I have an edelbrock 289 series intake and a 600 cfm edelbrock carb. I have AFR 165cc Aluminum heads. My concern was the manifold suffocating the heads. I was also wondering if a stock header replacement for a 65 would work in the place of the manifolds.That was my build. It works, there are a lot of pictures in my thread.
I also have the GT40p heads, which have slightly different spark plug location and the old manifolds are known to clear that with a bit grinding.
Because I'm living in Germany it is difficult/expensive to send parts that don't fit back... I think that this mid-length headers could also work, because they are made for 65-66 mustangs and they have a "normal" version and one for GT40P heads:
What I like with the manifolds, is that they are more quite in the engine bay (surface radiated noise is very little compared to headers). I have still some db-Killers in the exhaust that produce a lot of back pressure, so I don't know how good the exhaust will flow, if I remove them. But you feel that the engine is breathing not so well above ~4500 RPM at the moment. I also have a tame cam (stock 2001 explorer cam), so I do not know how good it will be with a better exhaust.
Down low it pulls STRONG!
Ragarding manifold, shortys, mid-length, tri-y or long tube headers: in my opinion on the street it doesn't matter much which one you have, as long (!) they flow enough (which refers to diameter). I think you can gain more with a lot of carburator and ignition tuning. But the old exhaust manifolds have tiny diameter and will limit exhaust flow at some point.
What do you plan to do with your engine?
When you installed them did you have to modify them to fit? What kind of trans are you running?My blackjacks were leaking and I ran across a set of never used Hookers for cheap. The hooker is a much nicer header. The walls are thicker and the flange is larger. Seals mich better at the head. Granted my blackjacks have close to 100,000 rust belt miles on them. They were on my old II in the 80's. But the hookers are much nicer. Clear the steering shaft without adjustment with a hammer. Heavier gauge metal.
I have a set of hedmans on the Mach I and the exhaust guy wouldn't put exhaust on as the collectors are too high. They are bent wrong and wont clear the trans crossmember. Not to mention the goofy under crossmember pipe. The Hookers are expensive but they are really the only choice in my mind.