'78 slant 6 hole in head

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beebeeri000

beebeeri000

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on my '78 /6 there is a hole in the side of the head by the #6 exhaust port and my '73 /6 doesnt have this so im not sure what it is
 
That is a port for the air pump. If you don't have an air pump, you need to block that port off or you will have an exhaust leak there.
 
ok whats the best way to block it off? since it doesnt have threads to i cand put a bolt in there
 
You can get a pipe thread tap, and put pipe threads in the hole and then put in a pipe plug. Just makes sure the metal chips don't get inside. Cast iron usually taps dry. Maybe post a pix of the are so we can assess it.

Are there bolt holes on either side, you can make a plate and bolt it on with some exhaust gasket material and copper RTV. You can buy that at better auto stores.
 
Never thought of that.....needs to have some meat all around the hole or it might break out, but not a bad idea if you can get one to fit tightly.
 
I've used a couple of smogger late 70s V8 motors over the last few years. The a body exhaust manifolds have an air pump port at the rear. I used freeze plugs and they worked fine. The size was something like 45/64, it might be the same on a slant 6.
 
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heres some pics of it
 
I've been functioning 50 years with several holes in my head. What's the problem?
 
I would definitely try the freeze plug first before tapping it. They're cheaper, and won't damage the head. If you tap it you're chancing those metal chips getting in there and you'll have a mess lol.
 
75Brougham said:
I would definitely try the freeze plug first before tapping it. They're cheaper, and won't damage the head. If you tap it you're chancing those metal chips getting in there and you'll have a mess lol.
Click to expand...
Yep, agreed with the hole being that big.
 
k so i got a 10 pack of 45/64 freeze plugs since thats the smallest pack that they sold and it was the same price as a 2 pack on ebay so is you know someone that needs one ill sell em for cheap to just earn the money back lol they'll be here in tmrw so ill know if they work tmrw
 
i have that same hole on the back of my head. someone sometime before me made a small block off plate and i would assume used apoxy to seal it up. seems to be holding well.

as far as afraid of metal shavings getting in there i wouldnt be. its just going to the exhaust. not gonna hurt anything in there.
 
The threaded whole to the left is for holding the steel smog pump line to the head. The factory used a block off plate and gasket to cover the hole, when a smog pump wasn't needed.

It wouldn't be hard to make a steel plate to cover the hole. In the past I have used the remnants of the steel line to make a block off plate.
 
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