Started the 235 up after it's reconstruct a few days ago, I wasnt able to run it for long, as the electric fan wasnt beefy enuf to keep it cool for a good 20 minutes. But got about 5-8 minutes on it at 1500 rpm, and it felt and sounded good. Put a 19" flex fan on it today and went for broke, but developed some strange symptoms. Hopefully someone can tell me whats going on here.
The general specs.....'61 235cid. Pertronix installed, with their flame thrower coil. Holley/Weber 2bbl. with hot water choke. One wire alternator conversion. Road draft tube converted to pcv, vented to vac at intake. 180* thermostat, 19" flex fan. Everything is fresh, right down to the ignition switch and tumbler in the dash.
The symptoms....At start up until engine reaches 180* runs like a dream. Smooth, no noise or misfire. As the temp climbs just past 180* it develops a slight misfire, and starts to labor. Oil pressure at 37psi until then, it drops rapidly to 30, and then more slowly til it levels about 21psi. Meanwhile at the vac. gauge, at start up til 180* rapid bounce between 19" and 20". Havent dialed in the carb just yet. Again, at the magic number 180* Vac still bouncing rapid, but reading 21"-22". Voltage readings, Key on, not started, reading 6.7-6.9 at the coil, immediatly after starting, I'm getting 17.8 to 19.4!!!!!!at the coil. Once the operating temp is hit, I have 12.8-13.9 at the coil. I have repeated this scenario three times, so I dont believe that it is anything internal in the engine itself. Whats happening as it gets up to operating temp? Is this an ignition/electrical, or cooling problem? Thanks for any ideas.
