Header studs 360

[Stu]

The rear stud on the drivers side has been replaced with a bolt, which feels like it’s stripped, can’t get it to tighten, so I’m losing coolant.

Before I do anything else, does anyone know the length of the portion of stud that should be into the head / water jacket, please?

It’s a double ended stud, UNC one end, UNF the end that sticks out. Just need the length of the UNC thread, so I can make sure I’m using the right length bolt.

Cheers.

[Dave999]

id get one 3x the flange thickness its bolting down
i.e 1/3 in the flange 2/3rd in the block or head

test it to see if it bottoms. and if it does use some fat washers or cut off the end to a better length and clean it up.
to bottom out it would need to go into the water jacket across the open space, through the water, and hit something big like the side of the combustion chamber..... i don't think you need to worry

if it doesn't hit something big i see no problem coolant will flow round it

just use sealant on the thread


or indeed get the correct stud

Internet says they are 5/16 1 3/4 inch with a fat unthreaded bit maybe 1/4 inch in the middle. i'd guess that the fat unthreaded bit helps seal into the casting if the hole is exposed to water at the other end, its usually wider than the thread and will seat into the hole when done up
the internet also says they are 3/8 - 16 thats what my hemi 6 ones are

so who knows....


I'm inclined to think the bolt made of steal will have become case hardened in it life due to heat cycling. rock hard brittle but will be fine, look for thread damage....
But maybe its the hole its going into that's the problem...!

maybe i'm just a miserable get who expects the worst....

if stuck for the weekend lock tite or super glue it in.... you might knacker the gasket at that end... and expect a tick tick tick but you;d be out for the weekend reasonably trouble free

return at later date with a helicoil (coil thread repair) or time sert/case saver (solid threaded steel plug thread repair) depending on how much meat there is to drill and tap and how horrible the hole is


Dave

[Stu]

Cheers Dave, but all sorted.

Mr P appeared from nowhere with the correct stud, so that was the first bit of good news. That still leaked like a sieve, but at least I knew it was correct.

Long story cut short, have now helicoiled it and no more leaks.

[Dave999]

super.....

good news


Dave