how to plug holes in ramshorn exhaust?

[hpcgmc]

I've got the original ramshorn exhaust manifolds from my 67 C10. I'm thinking of keeping these manifolds, since I hear they flow pretty well, without the leaking and burning plug wires that happen with aftermarket headers.

My manifolds have little holes from where the smog pump originally tied in with aluminum tubing. I've screwed bolts in to plug the holes, but now I'm thinking of having the manifolds powdercoated, so want a permanent solution that will look clean. If I just use steel allen head bolts before they are powdercoated, will they hold the powdercoating well?

Thanks!

[Coley]

I'm pretty sure those fittings are 1/8" npt fittings.
I would get some small, internal Allen head 1/8"npt plugs and then install them down flush with an Allen head wrench.
If you are in at any local supplier that specializes in automotive, hydraulic or even perhaps plumbing fittings they should be able to supply those.
The less popular option would be 1/8" npt plugs with and external male hex....but they will stick out a bit and be a little less attractive and a little more obvious.
My two bits.
Coley

[kwmech]

What you actually need is a tubing plug, a pipe thread plug will work, but the threads are not quite right and are tapered

[chiefcfd]

I used some brass plugs that I picked up at NAPA. You can barely see them in this pic. They have a slotted smooth head on them.

[68gmsee]

Just out of curiousity.. What if you installed some bolts and sawed them off on the surface. Then grind them down smooth.

[Orange Crate]

I welded mine shut. I've been running them for probably 8 years that way and no issues. I use Rust-Oleum 248904 Automotive 12-Ounce High Heat 2000 Degree Spray Paint, Flat Aluminum. If you have the time, they ask you to spray the paint on, then run the engine, then remove and respray the manifold again. It takes some time but the paint last longer if you follow the directions.

[Wrenchbender Ret]

1/4 in. pipe thread plugs fill the holes real well but are not the exact same thread.

[MARKDTN]

Drill them out a little bigger and use "freeze plug" style plugs. You can get them at CarQuest, NAPA, etc.

[hpcgmc]

Thanks for the ideas. I called around and cant get exhaust powder coated, but might be able to get them ceramic coated. Ny concern is a plug that will accept paint or a coating without flaking off.

[Kennuck]

Don't use a NPT plug. If you happen to tighten them too tight they can crack your manifold. Use the tubing plugs as stated above. You can get them at any Auto Parts Store. Beadblast the manifolds and plugs after installing the plugs the beadblasting will give you a nice finish to coat over.