[mpmsmuscle]

What are the best d-port headers to use with Kauffman D-Port heads 315 CFM. Application is a 69 Pontiac Gto with a 474 stroker, m/t with 600 plus hp. I was trying to find d-port headers with 2 inch tubes. I am running a 3 inch exhaust with Flowmaster Delta Flow 40 series mufflers.

[25stevem]

Here’s a guide.

[Steve C.]

As noted above it is the INSIDE diameter. You will have to figure in the material gauge of the header.
Example 18 guage material (.049) on both walls of a 1-7/8" diameter header will be about 1.775".


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[chuckies76ta]

https://forums.maxperformanceinc.com...d.php?t=863039

[tom s]

you can do 2in Dport headers.Requires the Headman 2in adapter plates.I have them on my 63 Lemans.The plates bolt to the heads and the header flanges have the holes so they are EZ to bolt up.Been out for maybe 30 years?You would need to have custom headers built on the car with them I think.Tom

[Jay S]

I think Tom your talking about using d port to round port adapters once sold by headman and Mad Dog? I don’t know the part number. It adapts d port heads to round port headers for 2” headers. Is that made anymore?

On our 68 GTO with d ports we have Mad Dogs. They are step headers, 1.875” for a couple inches out the heads, then 2” primaries with 3.5” collectors. I don’t think Mad Dog makes them anymore, but might be special order. They are a work of art, nicest header I have ever owned. They are used often for stock and superstock.

[tom s]

Actually they make Dport to 2in Dport also.Headman still sells the gaskets for them.Have not checked lately to see if they still sell the plates.Trying to do 1 7/8 or 2 in on a Dport makes getting the 2 center bolts in is almost impossible,is with 2in.With the plates it is beyond EZ.Tom

[tom s]

They still sell the flanges for 2in Dport outer.

[Steve C.]

I believe the technical term is Header Sub-Flanges. I had them on my Headman 1-7/8 race headers for the d-port heads years ago.


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[ta man]

What is your et/mph goal..may be easier just to use 1 3/4 inch? I'm running 10.6's/127 thru 1 3/4 inch headers.

[tom s]

I would use the sub flange even on 1 3/4!Tom

[mpmsmuscle]

Is the sub flange still available? If so where can I purchase? Thanks

[mpmsmuscle]

10.5 to 10.6 is the goal. Are you using the sub flanges? Which headers are you using?

[tom s]

Headman sells them.Tom

[wbnapier]

Here is the link: https://www.hedman.com/product-detail/10170

[mpmsmuscle]

Thanks for the help. 😎

[PunchT37]

These would go on my d port `69 GTO.




https://pertronixbrands.com/products...31797115486244

[tom s]

Pic of the plates on a engine run stand.Will run a set of 2 in Tyree Dports on it.Tom

[wbnapier]

That's a smart product. Should make install easier. Not sure why are manufacturers doen't do a subflange

[ta man]

Originally Posted by mpmsmuscle

10.5 to 10.6 is the goal. Are you using the sub flanges? Which headers are you using?

I'm currently using 1 3/4 Dougs...have also used 1 3/4 Super Comps