Finally got the head off my 503. HRL was kind enough to add Sodium Silicate(water glass) to the water since combustion air leaked into the water, due to some true genius not tightening all the head bolts. We(HRL and I) got it home from Arkansas, OK.

Started leaking again, so decided to do a valve job and replace the head gasket. Tried to get the head off, wouldn't move, tried lifting, wouldn't move again, added shop air to 3 jugs, no joy, added shop air to all 6 jugs-that is 150 psi times 4 9/16" bore x 6 jugs, tried lifting more, finally tried lifting at various ends of head, got air leak so I knew I was making progress, finally got it off after careful lifting and relaxing many times over the course of a month or so.

Head and block look OK. Going to mill the head 60 or 90 thousanths, since the compression ratio is only 6.5 to one. The moral of the story, is be careful with the use of Sodium Silicate and how long you leave it in. I doubt the addition of antifreeze made the difference.

Ed

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.