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I haven't decided if I should stay with stock exhaust manifolds or go to headers. If I decide on headers, I need advice on the easiest to install, Ones with no interferance to original inner fenders or parts. any help is appreciated.

Thanks, 66
 

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I haven't decided if I should stay with stock exhaust manifolds or go to headers. If I decide on headers, I need advice on the easiest to install, Ones with no interferance to original inner fenders or parts. any help is appreciated.

Thanks, 66
Headers will give you the best performance, and the most pain. I have a set of Doug Thorley's on my 69. They fit pretty well and have nice thick flanges that are good as far as sealing to the heads without leaks, but I still had to do things like relocate the brake distribution block and it looks like I'll still need to dimple one of the tubes a bit on the passenger side to get a little room for one of the lower control arm bolt heads. It just barely touches now, but with the engine moving in the frame when the motor mounts flex I'm concerned it might rub a hole in the header tube.

There are other options. I hear from pretty good sources that "Mad Dog" headers both fit and seal. I didn't learn of them until after I'd already bought mine and invested in having them coated. There's also a guy on another forum (either Pontiac Zone or Performance Years) who's in the process of making Tri-Y headers. Because they're 4 into 2 into 1, they should fit much better and not have the same clearance problems that full length 4-tube headers have. You'll find opinions that say they perform better/the same/not as good as 4 tubes, and I don't know which of them are correct. I suspect like everything else, it depends a great deal on the other characteristics of the motor (displacement, cam timing, exhaust flow velocity, exhaust port design, rpm range, etc.) as to how well they'll really work. You can save yourself some grief by not trying to go huge on the tube size. There most definitely is such a thing as having primary tubes that are "too big" for the motor. Tubes that are too big make the exhaust gas flow slower (bigger tube - gas doesn't have to move as fast in order to pass a given volume), and that does bad things to low end torque because now the engine has to expend energy to push the gas out instead of the higher flow velocity helping to 'suck' it out. More engines have lost power due to tubes that are too big than due to tubes that were too small. Unless you're making north of 600HP on a Pontiac, you don't "need" 2-inch headers - they'll actually hurt you.

I chose headers because I've never had them before and I thought I wanted max power, but I tell you, if I had it to do all over again I'd probably think pretty hard about it before I chose them over the repro ram-air manifolds. I might still pick headers, but I'd sure think about it more.

Bear
 

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If you go with headers, think about getting them ceramic coated. They will increase the longevity of them. I have my Hooker Comp headers coated for 7 years now and they still look pretty decent with minimal pitting. When I replace them after they start rusting/pitting more I will probably go with the d port ram air manifolds.
 

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All good advice, except I don't agree with the ceramic coating. It will get cracked and damaged when you use a sledgehammer and a drift on several of the tubes to get the headers to fit into the car. What then? And ceramic coating certainly isn't needed for longevity. I've had the same ugly, rusty Hedmans on my '65 for 29 years and they are plenty solid. Ceramic coating is a "feel good" addition to an engine compartment only, and is on the same page as steel braided hoses and billet pulleys. I would run the HO manifolds over the tubing headers unless I was running aluminum heads....then I'd install the tubing headers. With Pontiac D port iron heads, I think the HO cast irons are great.
 

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When they are scratched they will only rust in that one spot just like regular headers. The great thing about them is not looks but under hood temperature drop a lot.
 

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Doug's headers fit perfect and hit nothing. You just have to pick the drivers side of the engine up about 2 inches and drop them in. Perfect fit. Butler Performance recommends them.
 

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All good advice, except I don't agree with the ceramic coating. It will get cracked and damaged when you use a sledgehammer and a drift on several of the tubes to get the headers to fit into the car. What then? And ceramic coating certainly isn't needed for longevity. I've had the same ugly, rusty Hedmans on my '65 for 29 years and they are plenty solid. Ceramic coating is a "feel good" addition to an engine compartment only, and is on the same page as steel braided hoses and billet pulleys. I would run the HO manifolds over the tubing headers unless I was running aluminum heads....then I'd install the tubing headers. With Pontiac D port iron heads, I think the HO cast irons are great.
I've run ceramic coated headers on 3 other V8s for over 10 years each (including one daily driver BB Chevy) and have never seen it crack or peel. Yes, you can scratch it or wear through it with a hammer, punch, file, welder, etc, but it only rusts in that one place, versus old headers that are rusty all over. I have also successfully dented ceramic coated headers with a hammer and NOT damaged the coating at all, depends on how you do it.
The coating does seem to reduce underhood temps and definitely looks a LOT better than "ugly, rusty Hedmans" under the hood.
But for those who aren't concerned with how their engine compartment looks I guess it would be a waste of money.
As far using manifolds, there is a performance improvement in the use of true equal length headers vs. simple manifolds due to the scavenging effect of the exhaust pulses exiting the tubes. Just because an exhaust manifold will "support 450 HP" doesn't mean you won't make more HP and torque with an equal length header on the same engine.
Jeff
 
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