When the machinist looked at the head his opinion was that the head has had some work done to it in the past. He said that the intake guides had been replaced with new iron guides and it looked like the head had been surfaced before. So he ground the valves and seats to a fresh 45* angle, pulled 0.030" off the bottom and a bit off the side to flush up the intake divider. In a mis-communication he cut down the exhaust valve guides so valve guide seals could be installed on the exhaust. Oh well, it's nice work The block had 0.035" shaved off the top, which should leave the pistons 0.003" in the hole if my measurements were good. I'm going to re-measure it when I have the short block back together, but crunching all the numbers now takes the compression from 8.02 to 8.58. I only lost 1cc from before my chamber work and cutting the head, from 76 to 75. I measured out the port lengths as well and was shocked at how consistent the were. All measurements port to port only varied by a 1/16" which is likely the margin of error of how I was measuring them (with a wire). Averaging the top and bottom measurements the intakes were 3.125" long and the exhaust were 3.063". I think it will want an 8" runner on the intake manifold for an 11" induction length.
So it turns out there is not a whole lot to do for the intake ports, and a bit to do for the exhaust ports. It looked like the
The intakes against the two gasket types I have.
The exhaust against the two gasket types I have.
The valves were re-ground. The stock 45* seat angle. The black marks are just sharpie marks.
The head with the cc's written on it.
I finished all the metal work on the short block. Got 0.035" shaved off the deck and flexball honed the cylinders. I tapped all the spots where the baffles were riveted in with 1/4-20 threads so I can bolt the baffles back in after I add more baffling behind them. I've hosed off the block inside and out and dried it out with compressed air and fogged the cylinders and deck with WD-40. I'll probably re-paint it either tomorrow or during the week. For now I have it bagged and sealed.
Tomorrow I'll work on the last bit of head work, get the head cleaned all up and possibly re-assemble it, with the new valve springs. Get the pistons cleaned up and install the new rings. Work the over the baffling and re-install them. Finish working over the intake and exhaust manifold ports with the die-grinder and if I get really really ambitious I'll get the cylinders real cleaned out and install the crank and pistons. I need to shorten the head dowels and make sure the head bolts don't bottom out.
Rebuilding an OHC Pontiac 250 with EFI and a Turbo