[64speed]

Does anyone make a set of tuned headers for a Pontiac round port or d port? I see the expensive Dougs units but even they aren't tuned. I remember several years back Car Craft made a comparison on a SBC and it did make a difference. I know I'm comparing apples to oranges I just wondered if anyone did and how much they are?

[tom s]

What are you talking about "tuned"?Do you mean clocked?ALL tubes equal length?You might call MadDog.Tom

[64speed]

If you click on Dougs headers for example on the Summit website under the descriptions it will say tuned or not. Every pontiac header I looked at said no. I think it means equal length tubes etc and is supposed to make a difference and justify the price of a high end header. The only tuned headers I have ever bought were sandersons for a SBC and I had nothing to compare them to so I dont know if it made a difference or not but I want my car to have the best of everything that I can afford.

[78w72]

round port hooker super comps are tuned according to hooker. they are big 2" primary tubes & 3.5" collectors.

https://www.summitracing.com/parts/h...w/make/pontiac

[sts]

I have always wondered if it makes that much difference

[Old Man Taylor]

Doug's are not clocked. The old Headers by Ed were clocked. Clocked means the exhaust pulses merge into the collector sequentially, creating a swirl in the exhaust. It's a long story why, but I had to remove the 1 7/8" Headers by Ed for repair. I couldn't miss a race, so I bough a set of 1 7/8" Doug's. This made the change from a clocked header to an unclocked header. The best I could tell I only lost 0.03 seconds in the 1/4 mile. I was surprised it wasn't more. This was with my old 400 engine. Back to clocking - if you could look straight at the collector merge, the exhaust pulses would either go clockwise or counter clockwise in a circle. This makes the pipe routing more of a challenge. Most headers fire in a criss-cross manner.

[Old Man Taylor]

B/T/W, the clocked headers have a much sweeter exhaust sound.

[Old Man Taylor]

I ran across a couple of pictures of an engine I built years ago. I bolted on the headers just for appearance. These are clocked Headers by "Ed". You can see the order of the tubes into the collector on the passenger side. Top inside is #6, top outside is #2, bottom inside is #4 and bottom outside is #8. Note that the exhaust sequence results in a clockwise pattern around the collector, setting up a swirl in the collector. Without a clocked header the exhaust sequence is criss-cross. This sequence is why the tubes look contorted. It's more difficult to do them that way.

[64speed]

Looks like a real joy to install too

[Old Man Taylor]

Not as bad as they look. One tube on each side is separate and goes over the frame, so you have to cut out the inner fender panels. The biggest problem is the header bolt access behind each of the siamese ports(towards the firewall).

[tom s]

Jim,were those custom built on the car?I have had 3 sets of custom clocked headers built on the car and never had cut the inner fenders.Tom

[Old Man Taylor]

No, they were "off the shelf" from Headers by Ed. I also have a set of his round ports that were designed the same way.

[TCSGTO]

If all the pipes were equal length wouldn't the headers be "tuned" to the same rpm band? Might be good for certain race applications where you need max power in a narrow rpm range but for a street set up different primary lengths may create a broader power curve.

[b-man]

Find what fits best and has acceptable ground clearance with a primary tube size that's suitable and within your budget.

Don't worry about 'tuned' headers for a street car, you'll seriously never see enough gain with a far more expensive 'tuned' set of headers to notice any performance difference.

Doug's makes an excellent header that's perfect for your needs and readily available right off the shelf.

[Old Man Taylor]

Originally Posted by b-man

Find what fits best and has acceptable ground clearance with a primary tube size that's suitable and within your budget.

Don't worry about 'tuned' headers for a street car, you'll seriously never see enough gain with a far more expensive 'tuned' set of headers to notice any performance difference.

Doug's makes an excellent header that's perfect for your needs and readily available right off the shelf.

Ditto.