Originally Posted by Yoyodyne
I just did battle with the studs on a 36 LB block. The studs were crusty from sitting with the heads off and being roughly handled so I didn't care about saving them. I'm gunshy about heating any part of a flathead block because the last time I did I heated the area near the rear oil gally plug a little to try to uncrew the plug and before it really got warm it cracked the rear wall of the block from the bellhousing to the manifold surface. That was unsettling.
So I started unscrewing them, first budging them a bit with a 6" pipe wrench and an extension handle, then a Snap on collet style stud remover/installer and an impact wrench. I was pleased and amazed that all but 2 studs came out that way. Those 2 sheared off just below flush, and pretty easily at that. One on each side.
Those last 2 I went to work on with TIG and the washer trick, and expected them to come right out, I've done that before on lots of things. First I tried just welding the nut to the stud, building up a little weld then welding the nut on. Twisted the welds off several times. found some washers and attached the washer first, then the nut to the washer. Used up all the big washers I had. Ordered some nice heavy washers from McMaster Carr and went at it again. Broke off at least 15 welds between the 2 studs, lost count. When I had 3 of the heavy washers left. I decided I'd drill the center of the studs out to let them collapse a little to make them less tight in the block, then weld on them again.
I used a head as a drill fixture. I made a drill bushing out of mild steel with a .452 OD and a .250 ID. Bolted the head on with 4 bolts using my calibrated fingers (tm) to center the head on the bolts so the drill would be centered on the broken stud. Went at it with a 1/4" drill, those stock studs are pretty hard, the bushing allowed me to lean on it without worrying about alignment or walking off center. Went through both at 1/4. opened up the bushing to 5/16 and drilled both to 5/16" that's where I was going to weld, but I changed my mind and kept drilling becuse the drilling was going so well. Next drill was a T drill, that took out the root diameter of the threads. I then started trying to pick out the remains of the threads but that didn't go well, those studs are tough. I wound up chasing a tap in the hole, found that I hooked the reamains on the end of the tap and wound the last half of it back out of the hole. On the other side I went to a U drill and to my surprise, that caught the beginning of the remaining threads and screwed them in through the hole and deposited them on top of the intake port in the water jacket. It looks like a helicoil insert and the hole threads looks OEM.
I did not try the wax trick. By the time I thought of that I was welding washers and couldn't see getting wax past the hot washer. I did make the broken studs plenty red hot, hoping they would shrink but no luck there. I considered using stronger filler wire, I was using ER70s wire, but I was afraid if harder/stronger wire didn't get the studs out I'd have a harder time drilling them afterwards. I'll definitely try the wax next time.
edit - I sprayed the studs with Kroil for several days before, and during the process. Not a single stud showed any signs of it penetrating into the threads, every one was quite dry as it came out. That makes me wonder how wax could get in there, they seem to be an interference fit.
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