MTFCA Forum

How thick should flanges be for an exhaust header?

: ^ )

3/8" minimum. 1/2" better.

KWTownsend wrote: ↑

Tue May 06, 2025 3:48 pm

How thick should flanges be for an exhaust header?

: ^ )

Keith, if you are thinking of making a homemade header, yourself, I have a commercially made header flange that might save you some time. it is 1/4" thick if I remember. Contact me if you are interested.

3/8 minimum.

ModelTWoods wrote: ↑

Tue May 06, 2025 8:36 pm

KWTownsend wrote: ↑

Tue May 06, 2025 3:48 pm

How thick should flanges be for an exhaust header?

: ^ )

Keith, if you are thinking of making a homemade header, yourself, I have a commercially made header flange that might save you some time. it is 1/4" thick if I remember. Contact me if you are interested.

Keith can't use my header flange because it is for use on a T without an overhead. He has a "Fronty" and can't use it. someone who didn't give their name, messaged me that they would take it if Keith didn't. They are a mystery person.

As I recall the header plate that Mark supplies with his Rajo kit is 1/2 inch thick. I still managed to put a minor warp in it while building my header.


Andy

Working slow with a drill press, oil and a hole saw it's pretty easy to make one.

https://www.mtfca.com/discus/messages/8 ... 1543505202

This old post has a .pdf file showing the dimensions to make your own. Chad, I just noticed that this was from your inquiry about it years ago!

I have been building custom headers since my teenager years, 3/8" is your friend, bevel inside and out, match distances within 3% flow check if you can!

Hank

KWTownsend wrote: ↑

Tue May 06, 2025 3:48 pm

How thick should flanges be for an exhaust header?

: ^ )

From previous discussion
By Scott Elliott, Tigard, OR on Wednesday, November 28, 2018 - 06:32 pm:
Here is a pdf of a Header flange. It shows the dimensions between the ports and the bolt hole spacing. You might want to make the 2.25 dimension 2.50
Include the picture instead of the PDF of it

The header will be for a Frontenac. My son will do the fabrication and satisfy a "design and build" requirement for his welding classes at the local community college.
He will make one from steel, and if all goes well, a second one from stainless steel.

He made flanges 1/2" thick.

What is the best tubing to use to fabricate the rest of the header?

Stay away from aluminized and galvanized tube. Bare steel or stainless steel is best for welding. Stainless is a pain to work with, if you’re gonna build a bare steel header as a pattern, consider having it ceramic coated and be done with it!

Yes, have it CermaChromed after completion - Zoom-Zoom !

Speedway Motors sells very nice U bends for making headers in all sizes. First time buyers if you sign up for email you get a 10% discount.
Good quality VW J tubes work also but the cheaper ones don't have the best looking bends. The ends of the J tubes are smaller than the tube
this makes them easier to fit in a flange if that is the size you are using. I made the header for my speedster out of J tubes. The smaller end
can be pushed through flange & welded on the engine side of the flange so if there is any warpage it is in the direction that causes the least
issue.
Craig.

TeveS-Nor Cal wrote: ↑

Fri May 09, 2025 5:07 pm

What is the best tubing to use to fabricate the rest of the header?

Not recommended but my grandfather would use electrical conduit as it was cheap and available then paint it black. I bought the bends from summit last time. His header is still going great after 30 years so it it possible to cut the holes out with a torch, pick up material at home depot and build it in your backyard under a shade tree.

I used long u bends that came from speedway motors via Amazon. That gave me two primaries from each one. Same source for the cones. I gout the straight 3 inch tube from a muffler ship since normal shipping is only 4 foot pieces. I had them bend it a slight bit to follow the contour of the body.

Andy

A big box of material ordered from Stainless Headers arrived yesterday. Stay tuned...

Here is what he's got put together so far...

Mild steel, 3/8" flanges, 1-1/2" steel pipe (1-5/8" OD).
Still learning about heat and warping...

Now I need to find some 1-5/8" ID flex pipe.

Spencer is now working on the stainless steel unit...
: ^ )

Lookin good! Noticeable improvement with both tube fitment and welding. I like your flange bracing, did it keep the flanges in place?

We got the engine running but it was running really rough. Very sputtery and the intake manifold was really cold. I arranged a heat tube from the carburetor to an area near the exhaust header and it ran considerably better, so we made a heat collector and plumbed it into the carburetor. It runs much better.
: ^ )

We got the engine running but it was running really rough. Very sputtery and the intake manifold was really cold. I arranged a heat tube from the carburetor to an area near the exhaust header and it ran considerably better, so we made a heat collector and plumbed it into the carburetor. It runs much better.

: ^ )

My RAJO has to have HEAT !

What carburetor is that, Steve?

^^^^^^^^^^
Hmmmm… carb looks kinda familiar

Keith,
Looking good! I do not envy your son making the flanges out of stainless steel unless he has access to plazma or better still abrasive water jet.

Bill,
He cut them with a plasma cutter.
: ^ )

My Racer sports a Winfield SRBD.