Exhaust diameter

Vanspeed

Vanspeed

Well-known member
I ordered some u bends for my Flathead to make my own exhaust during this at home quarantine. My ‘36 engine is stock but I have a set of red’s headers. I ordered 1.75 u bends but I was shipped 1 5/8 instead. Would this make a huge difference? I was planning on no mufflers, just wondering what the smaller diameter pipe is going to do as far as sound?
 
About 25 years ago, I spent a lot of time and effort putting a 2" system all the way back on a '36 I had. (The car had a set of Fenton headers). Later, I found out that not only did it not help anything, and produced a "hollow" sound that was inferior too that which smaller pipes produced. I have heard that 1 1/2" pipes are just about right for dual "straight pipes" on a flathead.

And let's face it; modified exhaust on a flathead is more about "The Sound" than performance.
 
Yeah I am not going on performance. It will still feel powerful to me since it is in my ‘29 coupe that used to have only 40 hp. I just want the sound to be right.
 
Vanspeed said:
I ordered some u bends for my Flathead to make my own exhaust during this at home quarantine. My ‘36 engine is stock but I have a set of red’s headers. I ordered 1.75 u bends but I was shipped 1 5/8 instead. Would this make a huge difference? I was planning on no mufflers, just wondering what the smaller diameter pipe is going to do as far as sound?
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No direct experience with 1 5/8 inch tubing as I have always used 1 3/4, but wouldn't think it would make a big difference. At least better than 2 inch.
 
There is a question whether duals help performance on a flathead at all with any size pipes as opposed to a single exhaust system.
 
I am going to run with it and fab up my pipes. If it isn’t what I like I am only out $60 so I could always change it.
 
Also has anybody ran an equalizer tube? I hear that it is not needed on flatheads which I understand but I wonder how one would effect the sound?
 
Vanspeed said:
Also has anybody ran an equalizer tube? I hear that it is not needed on flatheads which I understand but I wonder how one would effect the sound?
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I heard a flathead with an equalizer tube a few years ago and it seemed to kill the beloved flathead sound.
 
I would think that duals on a flatty add little to performance unless you are running a full out racing engine. That "smashed header: video tells the same story - no difference.
 
Vanspeed said:
Also has anybody ran an equalizer tube? I hear that it is not needed on flatheads which I understand but I wonder how one would effect the sound?
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An equalizer tube would change the sound of a flathead and accomplish nothing performance wise.
 
I have little different experience. I have full length 1 3/4 exhaust with long Smittys.
There was annoying rapp when accelerating , I thought that it was because of plugged heat risers and unplugged them , same rapp. I made small (app 1") equalizer tube and app was gone and nice flathead sound is there all the time. Maybe I was just lucky...
 
vilanar said:
I have little different experience. I have full length 1 3/4 exhaust with long Smittys.
There was annoying rapp when accelerating , I thought that it was because of plugged heat risers and unplugged them , same rapp. I made small (app 1") equalizer tube and app was gone and nice flathead sound is there all the time. Maybe I was just lucky...
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You are correct, that is part of what the equalizer tube does, it cancels out some frequencies. A traditional Hot Rod engine would not have had one, so the sound is going to be different. But if you like that way it sounds with it installed then there you go.
 
Not trying to hijack the thread.....I just bought a set of Brockmans and could only get 2” inlet-outlet.....I had also planned on using 13/4 “ pipes......I have manifolds for duals .....is there an issue with bushing down on the inlet-outlet?......thanks.....Mark
 
flatford8 said:
Not trying to hijack the thread.....I just bought a set of Brockmans and could only get 2” inlet-outlet.....I had also planned on using 13/4 “ pipes......I have manifolds for duals .....is there an issue with bushing down on the inlet-outlet?......thanks.....Mark
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No, that's a common way to do it.
 
vilanar said:
I have little different experience. I have full length 1 3/4 exhaust with long Smittys.
There was annoying rapp when accelerating , I thought that it was because of plugged heat risers and unplugged them , same rapp. I made small (app 1") equalizer tube and app was gone and nice flathead sound is there all the time. Maybe I was just lucky...
Click to expand...

Interesting. I do no want my exhaust to have that annoying rapp. Thanks for your input.
 
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