tiny holes in head?

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68383GTS

68383GTS

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I have a 74 318.It has tiny threaded holes under each exhaust port.What are these for and do I need to block them off if my headers do not cover them?
 
they are small holes you'll have to plug all 8 of them up. Or like I did not notice they were even there and had 8 little exhaust leaks
 
for emissions I believe but do I need to block them off?
 

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Tap them and put 1/4" set screws in them deep enough so they don't stick out and hang up any exhaust manifolds/headers...


Then grind the bump on the inside of the port for them down....
 
Hit them with a MIG welder. Tapping cast iron sucks. You are never going to use them anyway.
 
Tap them, put in 1/4" x 20 set screws with Loctite and be done with it.....
 
krazykuda said:
Tap them, put in 1/4" x 20 set screws with Loctite and be done with it.....
Click to expand...

Yup. Done that a couple of times.

You don't even need to tap them all the way into the ports. I just get some short set screws, tap the holes about half way through, and run the set screws in until they bottom out. That way the set screw can't possibly migrate into the port. I still use a little loctite to seal them in. Just make sure the set screws don't hang out and interfere with the manifold or gasket, some of them can hang up on the exhaust manifold flanges depending on what manifolds you're using.

Some of the ones I drilled and tapped were already plugged with carbon, which is what will happen to any space left between the set screw and port eventually.
 
72bluNblu said:
Yup. Done that a couple of times.

You don't even need to tap them all the way into the ports. I just get some short set screws, tap the holes about half way through, and run the set screws in until they bottom out. That way the set screw can't possibly migrate into the port. I still use a little loctite to seal them in. Just make sure the set screws don't hang out and interfere with the manifold or gasket, some of them can hang up on the exhaust manifold flanges depending on what manifolds you're using.

Some of the ones I drilled and tapped were already plugged with carbon, which is what will happen to any space left between the set screw and port eventually.
Click to expand...

Oh boy! Not in to the head porting 10 minutes and broke of the taping bit in the second hole:banghead:
when I grabbed the heads from the shop (all disassembled and cleaned up) yesterday. l thought the welding idea was a fast and good one! ? When I told Ted at the machine shop he gave me a little look and said he"i wish you wouldn't":color: so before I started on my first time at porting I wanted to plug the little holes. I broke the 1/4 inch threader of in a little hole:violent1: I had no problem with the other three on my first head. So now I really want to just weld over that little piece that's broken inside there because it's made out of a hardened steel. I can't seem to drill out for an easy out. any suggestions?#-o
 
j par said:
oh boy! Not in to the head porting 10 minutes and broke of the taping bit in the second hole:banghead:
When i grabbed the heads from the shop (all disassembled and cleaned up) yesterday. L thought the welding idea was a fast and good one! ? When i told ted at the machine shop he gave me a little look and said he"i wish you wouldn't":color: So before i started on my first time at porting i wanted to plug the little holes. I broke the 1/4 inch threader of in a little hole:violent1: I had no problem with the other three on my first head. So now i really want to just weld over that little piece that's broken inside there because it's made out of a hardened steel. I can't seem to drill out for an easy out. Any suggestions?#-o
Click to expand...

@!#%&? Got it! !!
 
Why wouldn't you drill and tap for a pipe plug (NPT)? Get some steel plugs, crank them in good, and they'll never leak and never fall out. Not sure on the size but if a regular 1/4" tap is working in those, you can instead drill them with a "Q" drill (.332") and tap them with a 1/8-27 NPT tap.
 
Kittman said:
Grind the broken parts down and fill with some JB-Weld.
Click to expand...

I got it! But it wasn't a matter of grinding because it was a hardened tapping bit if it was just a bolt I would have drilled it an easy out but those taps are made of extremely hard steel and they don't grind you have to chip and chisel and be patient and get out but thank you

ps. no JB Weld a new race motor if at all possible
 
What is the casting number of those heads? They are probably 302's which are good heads.
Swirl Ports!
tmm
 
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