Finished the vacuum pump install last week and there was still enough blowby to see it escaping the seperation can. So did a leak down and was acceptable all but #3. BIG leak. Expected a broken ring (assembly stupidity or something) So had some friends help (still recovering from back surgery) and yanked the motor, pulled the head and the bore isn't scored, scratched,, whew!!!! so,,,?? what's up. then I saw it..... my round bore isn't round,, it's got a big 1/4" wide flat.
Picts to come but the head apparently was trying to lift, and the deck failed. FIGURES,, spent a ton on this POS GM 509 casting to use as a backup motor, and haven't even made ONE complete pass on it. So that's it,, anyone that tells you a GM 400 casting is worth 5¢ is out of their mind. Maybe for a street motor eeking out 1 or 1.2HP per inch,, but 600+ and it's JUNK in a heartbeat!!! And this block was a virgin 3951509 400 casting, maged, sonic tested, added splayed mains / align honed, cement filled to the bottom of the waterpump holes, bored and honed with torque plate, squared and zero decked stuffed with cubic dollars and the POS still failed!!!!
Grrrr, now have to find a decent priced block, with 400 mains, and standard pan rail, and start all over clearanceing for the 4" stroke. And all this started as a simple motor change to step the truck up a 1/2 a second
