I have been reading threads about this to eliminate the outer bolts from breaking on removal but I have not found anything specific.
I just bought a new exhaust manifold for my 63 dart and it installed fine.
I did have to drill out the outer bolts, one came out ok but the other I had to drill and retapped and helicoil, now I find this thread and wonder how I can correct this.
I am having some overheating I am looking into right now, new thermostat, cap and pump. I do see steam coming out of the back manifold hole that I tapped and helicoiled.
ANy direction on how to correct this would be helpful.
I suspect the radiator and have asked the wife for old stockings? WTH she says?
Thanks for your great help.
John

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Psychics will soon lead dogs to your body!

1963 Dodge Dart 270 convertible

I am guessing you did not apply sealant such as Loctite to the Heli-Coil or to the stud you installed into it, am I right? That hole backs up onto a coolant passage and so sealant is necessary. You'll need to drain the cooling system again, remove the rearmost stud, use brake cleaner to clean the stud and the hole thoroughly—make sure to get the threads all the way dry—then apply anaerobic sealant (LocTite #542) to the stud threads. Not so much that it's dripping off, but fill up the threads nice and full so they'll seal both the Heli-Coil-to-head and the stud-to-Heli-Coil junctions. Install the thread and allow the specified time for the Loctite to cure.

Before you refill the cooling system, you'll probably want to pull the freeze plugs and remove the lower radiator hose, then scrape around in the block and flush out the built-up mud.
If it hasn't been reworked in recent memory…probably!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I knew I could expect a quick accurate reply from here.
Thanks a million will do the fix and I appreciate the extra info on the freeze plug cleaning part.
Will keep you posted.
Cheers!

_________________
Psychics will soon lead dogs to your body!

1963 Dodge Dart 270 convertible