Judson,
It wasn't a stovebolt, but we just started up an engine that hadn't run in about 30 years. It was a Seagrave (Pierce-Arrow) V-12 that had been sitting under a lean-to over-looking a lake here in Missouri.
Like you, we got varying degrees of low compression, and 2 or 3 holes with none. We drained the oil, pulled the pan to clean the sludge, and checked the oil pump. We pulled the heads (flat-head engine) to examine the valves and seats - some (open all those years) had rust, all were dirty. We got a valve-seat grinder (vintage Black n Decker model, like a Sioux or Kwik Way) and did a clean-up grind on all the seats. We wire-wheeled all the valves, then chucked them in a drill press and treated the faces with emory cloth.
All valves were then lapped in. Of course, the piston tops were all cleaned of carbon, and the cylinders were all carefully cleaned. The few that had rust were carefully emory-clothed to clean them up.
We also took apart, cleaned, and reassembled the hydraulic lifters - not a factor in this case, obviously.
Everything was liberally sprayed down with solvent, including reinstalling the pan with 4 bolts and rinsing down the valve valley with diesel fuel. The pan was cleaned again, installed with new gasket and fresh oil. Both heads were bead-blasted, flushed and blown clean thoroughly, painted, plug holes chased, and reinstalled on new gaskets.
Rebuilt carbs and distributors (2 of each on this engine), reinstalled, timed, and primed. Took a lot of cranking, but she finally started up! Smoked like a banshee for 5 minutes. Second start up was much better. Third start up, dialed in the idle and mixture screws, ran her for 15 minutes, checked the timing - spot on - and now she purrs. The running with clean oil will eventually help free up the rings, and compression will improve. Also, it's still running with just jumper wires from the starter to the coils - the wiring is totally shot.
OK . . . when I recount all the work, it suddenly doesn't seem all that simple . . .
Basically, it amounted to an in-frame rebuild. But, didn't pull the engine, and didn't pull the crank or pistons. Now, if you pull the head, which I strongly advise, you may find cylinders that are desperate for a hone job or worse, due to heavy scarring or scratching. Personally, I would just do as we did, clean it up and get it running. You won't make anything any worse for the work, and you'll have a more complete picture to base your decisions on.
Don't know if this helps - I tend to ramble. &-)
-Michael
