LouieM

An ongoing thread on exhaust manifolds mentions that some of the desirable 2.5-inch ram's horn exhaust manifolds have a hole drilled for insertion of a hot air tube used by the choke system. A bit down the road I'll change to the 2.5-inch units in my rebuilt 67 327/350. Probably I'll find a set of manifolds with the hot air tube holes.
What will be the best way to permanently plug these holes? Weld them shut?

MikeM

Welding is one way. Kinda' permanent though. You could tap the hole and run a set screw in it. That's functional to fill the hole.

If it were mine and I didn't want to screw up the manifolds to where they couldn't restored with the hole, I'd tap some bits of lead in the top hole, flush with the surface and call it a day. No need to plug the bottom side if you leave the internal tube in place.

toms silver 60

I tried a 38 wadcutter bullet, it melted right down the hole, much to my surprise! I had previously patched a major crack on the left side exhaust manifold with Hot Weld with great success, so I tried it on the hole using another bullet as a temporary plug to keep it in place and it worked fine. Comes in a 2 oz clear tube, looks like powdered aluminum and graphite in a solution.

Made by FAS-WELD, typically sold at independent auto store counters, handled by Great Lakes Marketing of America, 1776 E 116th St, Carmel IN 46032.

LouieM

You've jogged my memory. I think JB Weld would work too, since it is rated up to 600F. Anyone happen to know if exhaust manifolds get that hot? I like the idea of a bullet as a temporary plug on the inside of the manifold to keep the sealing material in place.

LouieM

The JB Weld site says to not use it on exhaust systems, so that's that. Tapping the choke tube holes and screwing in a brass plug seems the least harmful way to go. I don't want to leave the actual tube in place, because it obstructs exhaust gas flow.

62Jeff

My IR gun indicates that my 65 327/350 exhaust manifolds are under 500 degrees, if I remember correctly.

MikeM

Exhaust manifolds under sustained power/load will approach dull red. How hot is that? 800-900?

If you're going to remove the tube, I'd tap the holes and plug them both.

Ironcross

braze it up and grind it flush.

obx2323

I just CAREFULLY and barely tapped the hole good enough to get a short bolt started. The bolt cut the rest of the threads=no leaks and reversible.

Hitch

What is the need to plug the hole? It is a tube that runs through the manifold and does not have exhaust gases coming out of it. I just have mine open with nothing covering it. Maybe I'm missing something? Dave

wmf62

you're right, but the tube can burn through or fall out, causing an exhaust leak. besides, the hole looks 'ugly'..

when i bought new Chinese manifolds, we drilled and tapped mine, threaded a short bolt in tightly, cut the bolt flush, and then bradded the thread/manifold interface to keep it from loosening. painted the manifold with cast iron colored manifold paint, and it was gone...
Bill

Olustee bus

Yeah hitch, you are missing something! J/K - I have run mine without plugging for 39 years. No problems yet. I will cross my fingers.

MikeM

[QUOTE=Hitch

Maybe I'm missing something? Dave[/QUOTE]

Yeah, you are. Post #6.

62Jeff

Ok Mike, why does my info about my IR gun experiences, mean that Dave is missing something?

LouieM

What is "bradded"? Typo for brazed or another process using brads?

MikeM

Ya' got me there Jeff. My mind read #5 and my fingers typed #6.

What Dave missed is in post #5. Louie doesn't want to retain the inner tube.

Hitch

I musta missed that part. Okay so do we think that the tube causes that much of resistance..

62Jeff

Good to know, I thought I was going crazy

LouieM

I'm sure it doesn't interrupt gas flow much, but every little thing counts in building a smallish V8.

obx2323

Mine went all tyhe way through to the inside. Don't know what happened but it did.