DDK - Die Deutschen Klassiker

Perhaps slightly crazy, but having had manifold bolts drilled out and re-threaded in the past by a specialist at considerable expense as I'm sure others have had to do, what do people think about chopping off the existing old heat exchangers and then splitting/slicing the manifold nuts - all to save the existing manifold bolts?

I cannot remember what the problem is with these bolts - do they shear off / break when trying to undo them?

The old exchangers will be binned anyway, and the nuts are very difficult to access....

Sounds doable to me - does it make sense?

If they are scrap cut them off
Grind the nut flat face as close as you dare and gently ease the nuts off
They will shear off if steel nuts used previously if not careful
Slowly does it

Yep, if you plan to bin em, cut the hell out of them.

Once off you can see the state of the studs. You mind still need to renew some as they can go a bit like brittle twiglet where they pass through the flange of the heat exchanger.

Thanks for your opinions, cant wait to attack this now

Perhaps I only need to cut off the 3 into 1 pipe, and probably best not to cut close to the exhaust outlets to avoid dust being thrown up towards the valves and possibly into cylinders!

There is a special tool to remove the heat exchanger nuts which goes though the gaps in the heat exchangers.... but if you're going to bin the heat exchangers anyway, then you may as well cut them off and put some heat on the nuts & studs to make them easier to remove.

Good luck!

Angle grinder, reciprocating saw and dremel, I would have thought cutting debris wouldn't be a problem. You could always rotate the crank like you are doing the valve clearances to ensure the exhaust port you are working on is closed.

To be 100% certain of getting the barrel nuts off, as well as the normal nuts, you really need an oxy/acetylene torch and
get them up to yellow heat. Otherwise there's always a chance that a stud will break or a nut will round off. You need to
be careful not to burn through an oil return tube though! Not easy to get to but it definitely can be done with the engine
still in the car.

Thanks everyone for your kind and useful suggestions!