Pulling Forum - Port matching

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Port matching

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Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=121581
Printed Date: 31 Oct 2025 at 5:00am
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Topic: Port matching

Posted By: TennMatt1
Subject: Port matching
Date Posted: 07 Apr 2016 at 12:55pm

Before I reassemble my manifold I was wondering if I would get any gains by doing some port matching? I have already cleaned up all my runners and got them smoothed out as far in as I could go.

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1954 WD45

Replies:

Posted By: Dan73
Date Posted: 07 Apr 2016 at 1:08pm

I asked that same question when I rebuilt my 160 gas got my d15. A couple of old timers who built hot rods in the 50s told me that they wouldn't bother with any motor that would spin under 3000 rpm. They claimed that the air flow with the stock parts was more then sufficient for motors at the lower speeds and that you only saw performance improvements when you got to the higher rpm motors don't know for sure but the two guys I talked to sure did build some nice hot rods.

Posted By: TennMatt1
Date Posted: 07 Apr 2016 at 3:15pm

I do turn about 3200 rpms if I open it up.

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1954 WD45

Posted By: Dan73
Date Posted: 07 Apr 2016 at 3:29pm

I would say yes you are up in the speed where it will help. I was told to make sure that all the transitions in the direction of the air flow are smooth. That is to say if the air flows from a small chamber to a larger chamber you don't need to worry about port matching because the air will expand and flow freely if it flows from a larger chamber to a smaller one you want to match the port ams smooth it out so the air doesn't hit a sharp lip. What I was told is that as air speed increases the smoother the transition the less disturbance you will have and disturbance robs power. So in your case I would try it. But in this case I only have second hand knowledge I haven't ever tried it myself.