Plugging smog holes on 302 heads

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Saetun

Saetun

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I'm asking those that have been there/done that with 302 casting heads, what's the easiest way to plug the emissions holes that are below the exhaust ports on 302 casting heads. I didn't have to deal with these guys on the old 675 casting heads that I replaced. I'm sure those that have done the 302 head swap could share an effective and possibly easy way to close these things up for good. I already had the heads bolted on when it was brought to my attention that they need to be sealed. Thx all.

You can see them here:
 

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Just tap and thread in some steel allen head set screws...might be a 1/4 tap, first find the set screws that seem the right size and then get a tap, there should be enough room, I done it with them on the engine in the car
 
Awesome. Looks to be 1/4" to me. Gonna need to get creative with a tap handle, maybe a small set of locking pliers. I'll pick up the set screws on the way home tomorrow. Frustrating to be so close to being done with the head swap & get derailed.
 
self tapping screws, coated in copper rtv. run them in with an impact gun and the heads should break off flush.
 
1980volare said:
self tapping screws, coated in copper rtv. run them in with an impact gun and the heads should break off flush.
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I like the idea but i cant get the impact in between the block and fenderwell. So just type-a tapping screws? 1/4-20 x shortest?
 
1/4-20 tap. Either use allen head set screws or normal screws and cut them off flush.
 
1/4 tap, allen head set screws and a little loctite. Done it a few times on 302's and 308's, works great.

Only thing I would add is that you really should drill the smog ports for the tap first, they're close to 1/4" but not super consistant. Some will probably work ok, others will be smaller and you could end up trying to cut too much metal with the tap. 1/4" x20 by a 1/4" or 3/8" works fine, they don't have to be very long. In fact, I like them shorter so you don't have to worry about tapping very deep, and you know the set screw won't go anywhere.
 
What i've done before is to run a 1/4'' drill bit through the holes, tap them with a 1/4''X20 tap, and then run a standard 1/4'' bolt in the hole, and then grind them off flush with the exhaust manifold surface. I used red loctite on the threads.
It worked well for me, the set screw idea would be easier though come to think of it.
 
All of the above methods will work. I use a stitch pin designed for reparing cracks in blocks and heads because I have access to them--The heads break off @ 7 ft/lbs of twist and then I file them flat. J.Rob
 
Hey jeff, use some small vice grips,just make sure you go slow and keep the tap oiled .having a good time in indiana,went to the indy track and drove the track later mike
 
bad440 said:
Hey jeff, use some small vice grips,just make sure you go slow and keep the tap oiled .having a good time in indiana,went to the indy track and drove the track later mike
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Just as bead as the rest of us, Mike. You're on the other side of the country & still found a way to log on, now that's dedication!
 
Jeebus Christmas!!! I just finished tapping & plugging the holes, thanks for the info, guys. For those who need to know, it is in fact 1/4-20. no drilling was needed for me, but don't blame me if you read this at one point in the future & break a tap off.

I made the mistake of mounting before plugging so it was a bear. Once I figured out the actual angle of the holes by inserting a hex key into one of them, I was able to match up the angle and the final 6 holes went super quick. That was a lesson I wont soon forget. Thanks again, all.
 
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