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Exhaust manifold hole

1967 satellite

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Here's a strange one. Motor is in the car. 383-4V. I need to remove the exhaust manifolds and send them out for coating. The 3 bolts that should have extended nuts but have hex nuts. How someone did that and why I don't know. I need to turn a 14mm 12 point socket down to fit in the hole, except I can't get a good reading even with calipers. Can anyone measure that hole and let me know. I think it's .640. Many thanks.

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Yes, as noted, the head should have studs beside the exhaust ports, with nuts on the visible studs, and sleeve nuts on the recessed studs in the holes:
Sleeve_nuts.jpg
 
No, I was able to get a light with a mirror and look down there and they are definitely hex nuts on the studs. All 3 are the same.

Hard to believe someone found a nut that would fit the stud and also fit in the hole. And have a socket that would work. Nothing surprises me anymore.

Could you just use something short enough for a depth guage? Piece of a zip tie?
 
I have the correct sleeve nuts or extended nuts (3) but I can't get the nuts that are on the studs off. Someone put a 9/16" hex nut on the (3) studs. That's why I need the exact diameter of the hole so I can turn down a socket to get in there. I believe the hole size to be .640"
 
Can’t you measure one on the driver side?

In the end does it matter? Grind until it fits. You might need to Jack up the motor .
 
No. I did that, to tough to get to. I did grind a socket but it's such a tight fit that the socket broke when trying to loosen it. There is very little room for error in getting the od correct on the socket that's why I want to machine turn it. I don't have a lathe so I need to take it somewhere and I want to get it right the first time.
 
This one measured ~0.6445" on both holes. There will be some variation depending on wear, rust, when made, tooling differences, etc.

PXL_20250208_231745482.MP.jpg
 
I think trial by error may be the exacting method required here.
Hopefully the heads don't need to come off...:BangHead:
The exhaust manifold is blocking the head bolts. Need to remove manifold first to remove head.
 
Here's a strange one. Motor is in the car. 383-4V. I need to remove the exhaust manifolds and send them out for coating. The 3 bolts that should have extended nuts but have hex nuts. How someone did that and why I don't know. I need to turn a 14mm 12 point socket down to fit in the hole, except I can't get a good reading even with calipers. Can anyone measure that hole and let me know. I think it's .640. Many thanks.

View attachment 1802927

View attachment 1802928
I believe I have a set.Will check in AM. You can have them for shipping Dave
 
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