390m crankcase overpressurizing???
got a head scratcher...any ideas???
I have a 76 f-250 "highboy" with a 390 modified. the engine ran well and strong, just really flat. so we were screwing around with it, tried to put a whole new exhaust on, and ended up breaking 8 bolts off in the heads. long story short, the whole thing snowballed on me. got all new valves, valve seats and seals, shaved the heads and cleaned up the intake manifold. new lifters, rods, springs and a more agressive cam (not wild, but has a nice cam lope to her). new timing chain, and pretty much everything else that needed some tlc was changed. now she runs great, the cam and lifters broke in beautifully. doesn't leak a drop, until i put it in gear. it pumps oil up and out of the top of the dipstick. and a lot, on the 1.5 mile test run, it leaked about 2 quarts out. i thought i snapped a ring, but the compression test was good, along with all the vacuum tests we did. also, the pistons and rings and cylinder walls were suprising spotless, not a mark on them. i'm freaking stumped, especially because it runs so rock steady, even while leaking. any ideas or suggestions would be greatly appreciated.
Last edited by ssgt highboy; 02-10-2009 at 15:51.
Reason: forgot something