Exhaust diameter
 

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?

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

1 5/8 will work just fine. I think the stock 40 exhaust pipe is 1 5/8".

Re: Exhaust diameter
 

There is a question whether duals help performance on a flathead at all with any size pipes as opposed to a single exhaust system.

Re: Exhaust diameter
 

https://www.google.co.nz/url?sa=t&rc...PnDFsEn3muWED4
While not relevant to total exhaust length and diameter , it may give you a good laugh as to how smashed headers affect flow.

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

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?

Re: Exhaust diameter
 

I heard a flathead with an equalizer tube a few years ago and it seemed to kill the beloved flathead sound.

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

An equalizer tube would change the sound of a flathead and accomplish nothing performance wise.

Re: Exhaust diameter
 

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...

Re: Exhaust diameter
 

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.

Re: Exhaust diameter
 

A '47 car came with 1 3/4" diameter exhaust, correct?

Re: Exhaust diameter
 

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

Re: Exhaust diameter
 

No, that's a common way to do it.

Re: Exhaust diameter
 

Ok....Thanks!.....Mark

Re: Exhaust diameter
 

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

Re: Exhaust diameter
 

That’s the only “rap” I can stand listening to��.... Mark