manifold thread repair

[johnr]

I have several exhaust manifolds with bad threads.
Looking at brazing up the bad section and rethreading.
Anyone done this with success ?
Also would there be any demand out there for this service ?

[BE_ZERO_BE]

I have chased the threads with a die before and sometimes it will improve the threads sufficient for a good seal.
It does not fully restore threads.
"Braze" might not make a strong long lasting thread.
"Weld" would be a better choice.

The manifold usually needs two things :
1. Thread repair or restoration
2. Straightening.

A new manifold costs about $85.
The biggest expense to restore a manifold would be oxy-acetylene gas to straighten and weld with.

YMMV

[speedytinc]

I pass on manifolds with bad threads. I have a die. Bad threaded manifolds go to scrap.
Brazing wont last when a manifold glows red. Welding is too costly time wise.

[John kuehn]

I straightened a manifold just to see if I could do it and it came out pretty well. Downside is that it uses up to much Oxygen and Acetylene. Wont do it again and will save time and money to buy a new one if I need another one. The one that I straightened had good threads and that’s the reason I saved it.
The repos are pretty good in my opinion and one of the better parts for T’s that’s being used. I bought a new one for my 21.

[Allan]

The new ones fit well and are well made, but they are different in appearance to the earlier originals if that is a concern to you.

Allan from down under.

[Humblej]

I do not think brazzing will work. I brazed a bad spot on the threads once and re-threaded it. Years later when I took the nut off the braze repair dropped out. I have run a die over ugly threads that cleaned up great.

[ModelTMark]

Just buy a new one, the lemon is not worth the squeeze to repair threads on an old one since these are available.

--Mark

[Jerry VanOoteghem]

... the lemon is not worth the squeeze...

--Mark

I like that!

[Craig Leach]

Hi John,
How bad are the threads? I have cleaned up some and installed a new or modified nut. The threads do not make the seal the flange
does so if the nut will tighten up good the manifold could be salvaged 2/3rds of the nuts I check aren't tight anyway. If you can't
get a nut tight real tight save yourself the grief and buy a new manifold. I would go out on a limb and bet this is why Ford went to
a clamp & flange in 1928. I have seen a repair for this that is a clamp & flange set up but it looks like NASA designed it so if you are
looking for concourse appearance that's out.
Craig.

[Steve Jelf]

I'm a skeptic on the claim that straightening an exhaust manifold burns up more fuel than it's worth. I really doubt that the oxygen and acetylene I use on one add up to anything near $95, or even $85.

I used to warn that the reproduction exhaust manifolds were available only in the 25-27 style, but in recent catalogues I can't tell if they're 25-27 or the earlier style. If you care about that, I would ask before ordering.

[TRDxB2]

It isn't always about cost or originality. Sometimes its about learning. tinkering and/or the satisfaction of a successful repair.

The Vendors exhaust manifold appears to have started in 1913 to early 1926. Perhaps there are subtle differences
From the MTFCA encyclopedia
MANIFOLDS
1909-1911
Intake manifold was “dog-legged” aluminum. Exhaust pipe fitted into the exhaust manifold and had asbestos packing, secured with usual nut[/b].
1911-1913
Intake manifold changed to straighter aluminum type.[ Exhaust manifold was the same as 1910 type[/b].
1913-1914
Intake was the same pattern as 1912 but was now made of cast iron (as per letter dated December 19, 1912). In January 1913 another letter specified the exhaust manifold was made for the flanged exhaust pipe. This new design exhaust manifold remained standard until late 1926.
1914-1926
Same as 1914 type. The 1915 sedan which had the fuel tank under the rear seat used a longer intake manifold (which lowered the carburetor) for better fuel flow to the carburetor.
1926-1927
Vaporizer carburetor with integral manifolds, used in some production in 1925 and 1926 became standard in late 1926.