Exhaust manifold
 

Thread size for this hole in the manifold. Believe it has to do with the AIR system I want to put a brass plug in it

https://live.staticflickr.com/65535/...76585f69_c.jpgimage by [url=https://www.flickr.com/photos/97391199@N06

Re: Exhaust manifold
 

Maybe here.


http://67-72chevytrucks.com/vboard/s...d.php?t=641828

Re: Exhaust manifold
 

If it's an oddball thread, run a pipe tap in it, I would use a steel plug, not brass.

Re: Exhaust manifold
 

Why steel? I thought brass would be better for corrosion. I’ll search around my Kennedy boxes see if I can find a tap and wheel bearing grease

Thanks Geezer read the thread, how do you find the info……search?

Re: Exhaust manifold
 

Brass is OK by itself, but when mated to dissimilar metal like cast iron it could cause issues especially with heat cycles. Will it work, I'm sure you would have no issues. I just like to keep different metals away from each other whenever possible. Good practice IMO.

Re: Exhaust manifold
 

I search with google images.

Re: Exhaust manifold
 

Good answer

Re: Exhaust manifold
 

I don’t think that’s an air pump hole… There would be one in each set of cylinders. Looks more like a manifold that has had the generator mount cut off. Does it leak exhaust out of the hole? I’d try a 3/8-16 plug and see if that would work.

Re: Exhaust manifold
 

To answer your question it does leak exhaust….

Re: Exhaust manifold
 

It's a port for the EGR or air pump. No such thing as a 3/8-16 plug, and that hole looks much larger than 3/8" diameter.
It will be an oddball thread so IMO the best fix it to run a pipe tap in it. I would start with a 3/8" NPT or maybe even a 1/2" NPT.