These don’t want to move…

[simon.williams]

Had to grind the downpipe off. These studs are firmly in place. I will probably end up drilling them out, but any ideas? Heat?

[Alec]

Hello Simon,

I find that heat works most of the time, I am fortunate that I own an oxy\Acetylene set so can get things really hot.
What do you have as a heat source?

Alec

[simon.williams]

A blow torch…not in the same league sadly…

[simon.williams]

Ha, welded nuts! And I think what helped was some sharp taps from a centerpunch from the other side, certainly seemed to make a difference. And the nuts welded close to the manifold.

Its the little victories!

[Mike Stevens]

I would now clean the threads with a tap, (5/16" UNF probably, or maybe 3/8" UNF, I'll have to check) with some engine oil on the tap threads.

Cheers, Mike.

[Dave B]

I'm sure the manifold studs are 3/8" UNC.
https://www.chriswitor.com/proddetail.php?prod=CW3519K

[simon.williams]

Thanks, new studs & exhaust are on their way from Chris, will look for good taps.

[Alec]

Hello Simon,

not forgetting brass, rather than steel nuts.

Alec

[simon.williams]

Thanks for the tips!

[Mike Stevens]

I'm sure the manifold studs are 3/8" UNC.
https://www.chriswitor.com/proddetail.php?prod=CW3519K

I stand corrected, but at least the idea was good - thanks Dave.