Going to send my 76 Dt400 cylinder in to get machined for a new piston. Whats a good way to remove the head studs beforehand without striping or breaking anything? Map torch? Had a head stud removal tool years ago but it damaged the studs threads on an old air cooled Porsche motor i tried it on.

Thanks,
Brett

I have a set of stud removal socket thingies that have like a locking clutch where i think three rollers run up ramps & lock on. The more you force it the tighter it locks. Think they would only grip on the un-threaded part if i sat it hard down on the top of the cylinder. Depends how much un-threaded area there is. Much like this one i found googling below. I have a set of 6-8-10mm, maybe 12mm not used them in recent times.
www.autotrail.co.nz/shop/service-tools/s...-8mm-stud-extractor/

2 nuts locked together...

Or 3 nuts even lol & cover all the thread.

Once a friend loaned me a set of stud installer/removers.  They were like an oversize outside diameter socket that threaded onto the stud...  you needed to use the size that had the right threads.  Anyway, they had some sort of cam/wedge mechanism inside that grabbed the stud when you turned the socket with a ratchet...  the harder you had to pull on the ratchet, the harder they grabbed. 

I had some really stuck studs that the double nut trick struggled with and that socket tool had no issues.  I was going to buy a set but they were stupid expensive.  Oh, and they worked to install too,  It only took a slight reverse turn to release the cam lock.

And yes, steel studs in aluminum can be difficult to remove after many years.  I recently splurged on a induction heater to remove some exhaust nuts on an old vehicle that I was certain the studs would snap and there was not room to fix that without removing the engine....  what an amazing tool!  You place the coil over the nut and press the button and in less than a minute the nut is red hot.  No flame or heat source...  works like magic.    If the head studs are really stuck I'd heat them up and use the melted wax trick.  (I'm sure you can youtube to find it).  We used to do that all the time to remove stuck engine studs in aluminum heads/blocks,. 

i.imgur.com/tEBPKBW.jpeg
   This is what I used on a old Model A to remove the head studs
 

Head studs generally come out easy unless they've been heavily loctited in which I've never seen. The damn things usually come out complete with thread just when you don't want it to happen miles from home. Mind you they'd have to feel dodgy on tightening for that to happen. Marks idea sounds super trick so I'll YouTube one if I can find it. Only thing that worries me about heating studs red hot is 'does' it soften what's above the cylinder & make it more likely to break off flush. I dunno, I'm just rattling the cage lol. Think Mark was talking about heating nut initially?. I'll go back & read. Must look up the wax trick too.
The locking tool I put a link somewhere is good But stud has to be full 8mm & it'll flatten the tops of the threads if it bares on them from what I remember.
Sorry just morning woffling.

I have been lucky to use the 2/3 ea. nut extract method.