Thanks HRDad, From your info, I'm thinking the main problem likely lies with the carburetor. Although the oil has remained at the same level, and very clean, I'm guessing a little too much fuel in the cylinder may cause some "washing" as you mention. May account for the drop in pressure? After engine has cooled a bit, I can re start, and have 37 psi, until the temp gets back to just over 180*
Leaking past the valve seals.....I hope not, the head was completly re built by a reputable local guy, new seals, all new valves, etc. With a total of maybe twenty five minutes of use, at idle, I dont think the head would be a problem, of course stranger things have happened.
The electrical system is 12 volt(1961 Apache 10). I removed the 12 volt generator, and ran the truck with a 12 volt alternator, before the tear down. But the voltage at 17+ volts bears more looking into along with the carb. Thanks for the places to start.
