plugging a.i.r. injection holes?

I put a b4b intake on my engine w/73 heads and realized that the b4b doesnt cover the air injection holes at the ends of the heads. What is the easiest way to plug these holes? what size plugs should I get ? JB weld ?
Thanks, Tim

 

Just the right size pipe plugs like Lowes sells idr what size they are.

 

I tapped mine with a 3/8-16 tap and used allen head set screws, I plugged all of my holes and hear risers as I'm using and early intake on my 73 heads

 

That's what I did as well: tapped and used set screws. Add some locktite for added peace-of-mind.

 

Did you do the a.i.r. holes with 3/8" ? because they look like 5/16". I know the crossover holes were 3/8 because I already plugged those.

 

The holes are around 5/16" so you have to tap them at 3/8-16 and use a 3/8" setscrew. The 4 big x-over holes are closer to 3/4". Maybe you mean 3/8" NPT which is pretty big. The above sizes are NC threads like typical engine hardware, not "pipe" threads.

JB Weld won't hold up to exhaust heat for long.

 

Last time I looked into it, JB Weld was good to 600 F, not enough as Mike said.

 

Ok , so I'm going to get the 3/8"-16 plugs. Should I bother sealing the threads with jb weld or no ?

 

I sealed mine with Permatex Ultra Copper RTV put it on the threads like locktite, I have done a couple engines this way

 

Be aware that the holes that you are going to be tapping into on the head lead directly to the bowl.It will be optimal to tap the holes with the heads off the engine and the valves removed.Using grease on the tap should capture most of the removed metal for the threads but make sure that you get it all.Soft plugs and staking the holes may be another option but I have not tried those.Good luck.

 

Yes, I took the heads off and valves out before I tapped the holes. I need to cut down the plugs I bought though - too long.