Another 302 head question

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ValiantMike

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I'm presently port matching set of 302 heads to install on my early 80s 318. I read sometime back that smog ports on 302s have to be drilled and tapped for a 1/4 20 set screw.
quote:
The only bad thing about the "...302"s are that they have smog ports, so that you need to drill ( slightly ) and tap with a 1/4 20 and screw in some allen set-screws to plug them up.

End quote

My question is, has anyone done this and how far in do you have to drill and tap for the set screw plug? Is there anything else to this? Appreciate any help. Thanks Mike
 
Mike, you don't have to drill and tap if you can weld, otherwise, purchase the drill and tap as a set from the tool house or sears etc.... and the allen scews without heads. Drill the hole about a 1/4 inch longer than the allen stud to be used. This way, after you tap the hole to it's end, the allen stud can be slightly counter sunk but not bottomed out in the hole. Lock tight it for good measure.

The length of the allen stud should be kept to a min. length. There is plenthy of room to drill for a long stud, but why tire your arms out for a inch long stud drill and tap session for 8 holes when a shorter one will do?
 
Rumble, I can just weld the smogport holes on the outside and thats it? I was just wondering about the inside end of smogport in the exhaust port. I imagine that won't help the flow, but I don't see how anything can be done about it. Thanks Mike
 
Well, if you can get some real good penatration on the weld, weld them up good. Grind them down so theres no problem with the header flange.

Now the hump inside the port shows very little gain in cfm flow when ground away. The air flow is best improved when the roof is touched. NOT the floor. The exhaust under pressure when the exhaust valve opens is forced out and hardest on the roof rather than the floor of the port.

If your home porting and not very exper. in what works and not, leave it alone or just level the hump even with the floor at best and most. Again, the cfm gain is very little.
 
Thanks guys. To tell you the truth, I'm a little leary about going past the valve seat and doing much in the bowl area. I'll have to see if I have more balls tomorrow. I port matched intake ports on one head already and needed to know how to deal with the smog ports. Mike
 
Then leave it alone. BJR is near by and do a mild job for you. I've seen his work before and it gets a thumbs up from me.
 
Regauding smog port holes , I took tapered steel pins , slathered them w/ JB weld , and pounded them in. After the epoxie set, I ground them flush. It may sound crude, but that was 4 years ago, and I still drive it daily.
 
If it works....it works. I actually knew a guy that stuffed and shoved aluminum foil in there. It worked. Though I do not recomended it.
 
i just went to homedepo and got 1/4x3/8 stainless steal allen set screws screwed em in no problems
 
I have another question. On one of the middle cylinders, in the exhaust bowl area, is a port going back towards the intake area. What is that for, and do I do anything to it when porting or installing heads? Thanks Mike
 
No touchy, that port is for the intake heating.
 
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