OK Gents and Ladies.. this issue isnt as simple as it sounds..
We bought an engine out of a 55 chevy thathad been replaced, because they "couldnt make it run right"
I wont go into all the issues with that...
The rotating assembly was together, the heads off.., cam was out.. Eagle crank, pink rods with arp bolts, speed pro hyper pistons with coated skirts.. Took it apart looked everything over. measured the crank, ordered new rod/main bearings.. measured the bores, and ordered new rings. Pulled the cover off the melling 55hv pump and checked clearances... reused it, like new..
Bolted it together.. installed the canfield alum heads, roller rockers, used break in lube with zinc etc...
Engine fired in first two revs, and ran wonderfully... I set the idle screw to run at 2000 rpm to let it run and break in, walked aroudn the front to watch gauges. .. about the time I looked at the oil pressure gauge it said 70PSI... but started dropping.. I watcfhed until it hit 5 PSI and shut it off.. it never stopped or slowed. it dropped like the second hand on a clock without pause...
Pulled the pan, put a new punp and different pickup tube in it. changed the filter and bypass and restarted... same issue. Oil pressure held for about 1 minute, then started dropping.. watched until it hit zero and the lifters started to clatter and shut it off... It has a mechanical gauge on the stand.. I tried a second gauge with the same results.... Just to make sure...
Pulled the crank and sent it in to have it checked, ordered a new cam, installed NEW cam bearings. Machinist said crank was good, he polished it and got me another new set of bearings to match. I checked the block for the plugs in the galleries. Made sure no one had drilled a hole in any of the front plugs for oiling the gear drive etc... reassembled.. started it... same issue exactly.. I figured it had to have a harmonics crack in the block along one of the main gallery's...
I took another block, had it bored, swapped all the parts in... fired it yesterday, ran one minute and the oil pressure started to drop... and went to 0 after watching it slowly go down for several moments... I shut it off, threw a few things. Drank a few beers staring at it, trying to think of reasons it might be doing this... I am now at a complete loss.. I have built a LOT of engines in my time, and have never hit a SBC I couldnt figure out.. this one has me stumped.. Looking for help, ideas, anyone thinking outside the box... What can I check here?????
Frustrated beyond belief... Thanks for any ideas or help guys!!!