# D-port or Round port Headers



## Logchain (Nov 29, 2011)

Quick question, I have d-port heads and im getting ready to buy some headers. I have read that round port will work on d-port and are sometimes better? The small edge on the port floor keeps the exhaust from reversing back into the combustion chamber?

Going to pick up some dougs and just need some guidance on d-port vs round port and which style I should get
Thanks


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## gambit45 (Jun 12, 2012)

I'm no expert but I would think that using "round port" headers on D-port heads would create a disturbance in air flow where the exhaust ports meet the header itself. I've never encountered a problem with the flow of D-port headers to D-port heads. Just my .02 cents.


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## BearGFR (Aug 25, 2008)

They won't fit - you've been misinformed. The openings on the round port headers will be too far apart and will leave a portion of the exhause ports in the heads completely uncovered. Also, although I haven't looked to be sure, I don't think the bolt holes on the center exhaust ports will line up right either.

Robert


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## geeteeohguy (Feb 2, 2008)

I agree with Bear....and Robert, too. Don't mess with Texas!!!


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## lars (Sep 28, 2004)

BearGFR said:


> They won't fit - you've been misinformed. The openings on the round port headers will be too far apart and will leave a portion of the exhause ports in the heads completely uncovered. Also, although I haven't looked to be sure, I don't think the bolt holes on the center exhaust ports will line up right either.
> 
> Robert


:agree
That's correct: There is no possible way you'd ever install round-port headers on a D-Port engine - it would be easier to install headers off a Ford Pinto on your D-Port than to try the round-ports... The center-to-center distance on the 2 middle exhaust ports is different (wider) on the round-port engines, and the bolts for those ports, and the end ports, are much farther apart than on the D-port heads. You could get the forward and the back bolt to engage, and that would be it... and you'd have massive leaks.

Here is the alignment difference between D-Port and Round-Port (I've lined up the forward and the rear bolt holes, which are the only holes that will line up between the two components):


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## kjk990 (Sep 1, 2010)

I don't know... That doesn't look that far off. Does it?


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## BearGFR (Aug 25, 2008)

kjk990 said:


> I don't know... That doesn't look that far off. Does it?


Just use a little silly-cone sealant --- you'll be fine.... :rofl:

Bear


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## lars (Sep 28, 2004)

I'd drill new mounting holes right into the head water jacket and then use a little silly-cone on the header bolts to keep the heads from leaking coolant... To plug up the gaps between the port mismatch, I'd jam toothpicks coated with JBWeld into the gap area until it's filled up. Let it cure, and then grind it smooth.

I have thoughts about special uses for duct tape and bailin' wire, too, but I'll save those handy tips for the next post.

Lars


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## Logchain (Nov 29, 2011)

Thats why I asked. Thanks for the replies and the pics. Dougs D-port it is.


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## lars (Sep 28, 2004)

Log -
In re-reading the replies you got, I realized that it could come across that we were 'razzing you for the question... I hope you know that we're certainly not busting your chops for the question, because you just threw something forward that had been told to you and, and you wanted to, smartly, verify the info.

But we'd sure like to know what kind of person it is who gives people like you this kind of nonsense information: Obviously, whoever came up with this, doesn't have a clue what he's talking about, and if you don't have a clue, why would you recommend something you know nothing about..? It would make as much sense as me offering marriage advice...

...and keep asking those questions, and play along with our twisted humor.

Lars


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## BearGFR (Aug 25, 2008)

:agree sometimes it's funny the things that people will try to tell you ---- not so funny if you follow their faulty advice and wind up with problems and wasting money.

Bear


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## Logchain (Nov 29, 2011)

No worries I didn't take it that way at all. I don't know a whole lot about anything lol, still learning. I noticed there were two types of headers and I was mentioning to a "car" guy that I was gettin some d-ports. He thought that the round ports would fit because they were bigger than the d-port and thought they would be better. Turns out he was way off, Either way I was unsure and knew I would get a straight answer here. Thanks again for the help


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## goatman77 (Dec 19, 2016)

*looking for advice*

Square peg round hole doesn't work. I'm trying to find headers for my 69 gto convertible 4speed conv., has thicker frame z bar linkage, bought with headers 35 years ago tried headmans pass., worked. Drivers side didn't, called headman and they don't make them, OPG doesnt have them either. I don't know what to do.


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## BearGFR (Aug 25, 2008)

I have no personal experience with them, but I have heard that MadDog headers fit well. Doug's are generally "fair".

You should expect that NONE of them are going to be bolt-on with no problems, especially on a 4-speed car with transmission back drive to the column lock. If you want a good compromise between performance and ease of installation, go with reproduction RamAir manifolds instead of headers.

Bear


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