# Aluminum Ram Air IV D-Port heads From speedmaster



## GTO Floored (Dec 4, 2021)

Thanks for everyone who reads and reply’s 

I have purchased Aluminum Ram Air IV D-Port heads for my 455 and having trouble getting headers to fit the heads . I purchased the Heads for Speedmasters #17203-2022-04-23-0233
Any suggestions ?


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## GTOTIGR (May 3, 2020)

Hi GTO Floored.

Ram Air IV heads would be round exhaust port heads. Ram Air III would be D-Port. I was only able to locate Speedmaster round port heads.



https://butlerperformance.com/c-1459644-cylinder-heads-top-end-kits-speedmaster-aluminum-cylinder-heads.html



It looks like Summit has Doug‘s Pontiac round port heads. There are others…


https://www.summitracing.com/parts/dou-d523?seid=srese1&gclid=Cj0KCQjw1bqZBhDXARIsANTjCPKpUQk0NXsrJal9tSVHky4H5hD44RRLh7kwvPIfIEUA4wsdiMxJTL8aAp3IEALw_wcB



When you say you’re “having trouble getting headers to fit the heads” - what does that mean?


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## ponchonlefty (8 mo ago)

speed master heads only have the round port heads. you will have to use the round port headers or manifolds.


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## BearGFR (Aug 25, 2008)

GTO Floored said:


> Thanks for everyone who reads and reply’s
> 
> I have purchased Aluminum Ram Air IV D-Port heads for my 455 and having trouble getting headers to fit the heads . I purchased the Heads for Speedmasters #17203-2022-04-23-0233
> Any suggestions ?


I see the problem. You're thinking that these Speedmaster Heads are D-port because the port floors where they exit the head are flat. No, when it comes to headers and such (and because they're listed as RA IV heads) these are considered round port heads, despite the shape of the port floors. When people talk about Pontiac D-port heads, they're referring to the distinctive shape of the center two exhaust ports. In Pontiac-dom, "D-port" vs. "round port" is also about the port spacing. Here's an image from Butler that plainly shows the difference:










You're going to require round port headers for those heads.

Bear


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## lust4speed (Jul 5, 2019)

Just an interesting sideline. I was at Flow Technology (Juan Mendoza) in Garden Grove, CA a few months ago and he was just starting to work on a set of Speed Master heads for a client. Juan does great work and his prices are very reasonable (just don't be in a hurry). He had just completed mapping the flow of the as-cast S.M. heads and was pretty happy with the results. Both Kaufman and Edelbrock as-cast D-port heads come in around 260/265 CFM untouched, and these Speed Master round port heads flowed 289 out of the box, so they showed a lot of promise. I need to get back to him and see how they finished up.


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