"302" heads

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furydan

furydan

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So I got a set of 302 heads from an 88 fifth avenue for my 71 318 block. I noticed there are holes on the exhaust port side of the heads below each of the exhaust ports. I guess they are some sort of pollution control fixture. When I pulled the heads from the 5th ave, it had those metal tubes attached to the exhaust manifolds. What am I supposed to do with these holes when I go to put the factory early a body exhaust manifolds on? The holes are not going to be covered by the manifolds. I just spent 400 on these heads so I hope I will be able to use them.
 

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Did I get the wrong heads...I've read the threads on the 302 heads and the 0 deck block with KB pistons...Never heard about having to plug the holes.
 
they started with the smog holes in the late 70s. iits common.
 
I recently did that for clhyer here on the forum. Tapped them and screwed little set screws in. Works good.
 
ok next question...Do I need to take the heads back off of the motor? Of course I put them on before I knew I had a problem...
Also...Any idea scamp on the size of the set screws you used?
 
I looked at the 1/4-20 last night and it just looked too big for the hole. I did thread a 12/24 tap in there and it seemed to cut the threads like it should. I just did 1 hole and today I am on the hunt for a set screw to fit that 12/24 size.
The 1/4-20 would need the holes drilled bigger.
I guess JB Weld wouldn't work in this situation...
 
That's odd. I always use 1/4-20 and I've never drilled them before. The tap just threads right in. I use red locktite and I've never had one loosen up. So long as you know it's tight, anything will be fine.
 
Yeah, the guy at the hardware store said the 12-24 tap is a bad size to use. Not many fasteners come that particular size and he had none. He said go with the 1/4-20 and even sold me a drill bit to make the holes bigger. So hopefully tonight when I get home I can get this thing buttoned up and ready to paint. Maybe I was just cautious last night when looking at the 1/4-20 tap. Didn't want to do any damage that I couldn't fix.
 
Well, I went home, stuck that 1/4"-20 tap in the hole and started turning. What do ya know, it's working. So 30 minutes later, all holes were sealed!!!
Thanks for everyones help....
Dan
 
good info i will be doing the same thing on my 714 heads they have those holes also. Will the allen head screws clear most any headers or manifolds besides the late 80's early 90's manifolds??
 
snowmobiler7c said:
good info i will be doing the same thing on my 714 heads they have those holes also. Will the allen head screws clear most any headers or manifolds besides the late 80's early 90's manifolds??
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Tap the holes enough to get the screws in flush.
 
You actually want to be able to set the plugs just past flush by about 1 thread. This way you can tighten the plug and stake it into place with a center punch.
 
I used 1/4-20x 3/8" set screws and cut the threads about 1/2" deep. Then used red loctite and tightened them up...Hopefully I will have no leaks once I get the motor going.
Got the preoiling done last night and by the weekend should have the motor painted and ready to install.
 
Well, everything is in the car finally...I had to take a grinder to the head where the d.side exhaust manifold goes down because the early a manifold sort of "hugs" the block there and it was hitting some of the casting flash and the area where the smog"holes" are on the head. I didn't realize it until I had snapped the manifold trying to tighten it. Its all good now after busted 2 manifolds and having one welded.
 
Just imagine....welding up the holes, takes less time, and less effort, and less money. I weld all of mine....I am not trying to save them to use at a later date....I want them omitted...FOREVER.

But yall do it like yall do it.....I'll save my money for parts.
 
Prine said:
Just imagine....welding up the holes, takes less time, and less effort, and less money. I weld all of mine....I am not trying to save them to use at a later date....I want them omitted...FOREVER.

But yall do it like yall do it.....I'll save my money for parts.
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Geez...30 minutes with a tap, and 2 bits for 8-Allen grub screws is really not a budget-breaker. If it is, you're in the wrong hobby!
 
The holes im my 360 heads were already tapped. Screwed some allen plugs in with loctite
and they were done.
 
Prine said:
Just imagine....welding up the holes, takes less time, and less effort, and less money. I weld all of mine....I am not trying to save them to use at a later date....I want them omitted...FOREVER.

But yall do it like yall do it.....I'll save my money for parts.
Click to expand...

I did the same after I almost broke a tap in my heads. After dicking with that tap, I said F it and busted out the old buzz box and laid about a 1/2 inch of eni55 nickle welding rod in each hole. I was done in about 10 minutes.
 
I had to grind the smog port boss down on the back drivers side too. nasty exhaust leak with early A manifolds.
 
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