Thanks, Oly!
Sounds like you've twisted a wrench or two in your time. I did a thorough check of the #1 cylinder water jacket area when we switched to the different block, and found no problems. The rest of the junkyard block was in pretty good shape, but #1 was worn so badly it needed a sleeve. Is this commom to 250's? All the rest of the cylinders cleaned up at .030 oversize with no problem.
I've used the 307 V-8 pistons on several 250 buildups, with good results. One in particular in a Nova could run with the V-8's after a little bump in cam profile and compression. It belonged to one of my students in the trade school where I was teaching who wanted a hotrod a little out of the ordinary.
At least this time, there's a sleeve in the problem cylinder, so I can re-sleeve it without going to yet another block. Just a lot of work to do another complete teardown! I'm leaning toward replacing the head, even if my head shop guy doesn't find a problem with it. It's the only common factor in all three failures. I'll probably go with a different rod in that hole, too. All the other cylinders are showing NO problems at all.
I've got four Onan turbo diesels, inline 6-cylinders UPS used in their big brown vans! They used them interchangeably with 292 GMC's, and **** 300's, all with the same engine mount and bellhousing setups. They used the old late-50's Chevy hydraulic clutch bellhousings, 12-inch clutches, and New Process 235 4-speed transmissions! Direct swap into a Chevy pickup! That would solve the problem, bigtime!
Jerry
