sounds like a clearance issue, but the oil pressure regulator is an intriguing idea.
I need to re-read all this stuff, but what is different on this engine now since that last time it was 'ok'.
Bob
(stuck at home the week of BG)
I'm going to give the rundown since the beginning (sorry it is so long).... so it will all be in one post....this is all from memory and dates back nearly 4 years ago at this point..... but I think I have the order of events pretty close.
My GN originally went down at 159k miles easing home from work one day in the rain.... it jumped time.... shame on me for not changing the original timing chain and gears out before that. Tried to put a 204/214 flat tappet cam in the car along with a new chain..... car ran about 100 miles before it smoked the stock turbo bearings.....and spun 2 rod bearings and a main bearing. Apparently I had little or no oil pressure as the GN came with no oil pressure gauge.... and the connector on the sensor that sets off the idiot light was melted messed up... so it wasn't even connected...
That numbers matching motor is fixable.... with a crank, 2 rods, a line bore... etc. I decided to moth ball that motor and "play" with another motor so I didn't mess the original one up.
After a few days searching in the local junkyards, I found a SG1 109 complete engine that had the rolled fillet turbo crank in it.... picked it up for $50
I disassembled it completely.....had it vatted, shot blasted, bored .030, decked, steel caps installed, line bored, new cam bearings installed... etc. My Buick buddy then built the engine using my original known good timing cover off my '87 GN that was built up using a booster plate and a high volume gear kit.....218/218 hyd roller cam....poor-boy hyd roller lifter conversion....
From that point I installed the newly rebuilt SG1 engine in the car the first time.
1.) On the first crankup.... I had the cam sensor off some so it didn't crank right away..... and (looking back) one time it was spinning over funny... kinda like I had the initial timing too high on an old school motor.... it acted like it locked up during cranking... then broke free instantly. I reset the cam sensor.. with a homemade cam tool.....then it fired up like it should. Initially sounded fine... oil pressure was great..... but 20 min into it idling... oil pressure was down to like 15 psi idling. Drove the car about 20 miles easing around.... got back to the house... 0 oil pressure idling.
Pulled engine out. I wanted to check rods and main clearances myself..... plastigauged my mains and had some close to .003..... I thought this had to be it....(my mistake...should have pulled it all the way down) so I bought some .001 under bearings and had them dry film coated..... assembled it.... checked all clearances.... not one was over .002 on the rods or mains.... I thought I had this licked.... so I installed it in the car
again.
2.) Cranked right up.... good oil pressure..... but the longer it sat idling.... the lower the pressure got. Made my 20 mile loop.... came back.... popped hood.... 0 psi idling..... I was
..... I never should have re-assembled that motor without completely disassembling it..... I had to have missed something..... so out it came again.
This time I hooked up the priming tool after I got the engine on the stand and with the intake off....I could see oil blowing out around one of the cam bearings down through the little holes in the lifter valley. Upon disassembly..... the cam wouldn't come out.... turned out the #2 cam bearing had spun.... gluing itself to the #2 cam journal. I had to get the # 1 bearing out... then the #2 bearing would come through the front block journal. In hindsight.... I think this bearing spun before the motor fired up the very first time. (see above when motor briefly locked up while trying to crank it the first time) After talking with Lee Thompson.... he said the front and rear cam bearing was a little larger OD but the same ID as the other bearings.... and that I could put a #1 bearing in the #2 hole in the block if I bored the hole out to fit..... which is what I did..... then re-assembled the motor (cam was unhurt) with new coated rods and mains..... again... clearances were all between .0015 and .002.
3.) Installed the engine again! Cranked right up.....good oil pressure..... but 20 min of idling.... pressure is down real low again..... by this point.... my patience is wearing thin.... this ain't fun anymore. To rule out something funky going on with the poor-boy hyd roller conversion.... I pulled the intake and put a brand new set of morrel lifters.....new pushrods (different length).....put intake back on...... buttoned everything back up.... cranked it up..... same thing.... good cold oil pressure.... but the longer it sat idling..... the lower it got... to the point it was less than 10 psi or so idling.... and I already know what would happen if I took it around the block...
At this point... I had so many other posts and responses in my other thread.... the next logical step was the oil pump.... so I messed with it.... tried some stuff Lee Thompson suggested.....then some stuff Earl Brown suggested.....at the end of me messing with it... I had ditched the HV gears..... polished out the imperfections of the cover on a piece of glass and sandpaper..... did the EB oil pump and timing cover mods...... and reassembled the front cover and put it back on the engine.....which at this point.... was still in the car. Fired it up...... same result. At this point I am beyond torqued off.... so I let the car sit for about 3-4 months... then I pulled the motor out..... and it is still sitting on the stand.... waiting on me to do something. I have pretty much convinced myself it has to be in the cam bearings or some crack in the block that has been missed up to this point that is opening up more as the engine gets hot and letting the oil hemorrhage out....
I have about made up my mind... if I don't find anything... to set that block aside and build up a stock bottom end that I now have enough parts to do with another block.... and put my roller setup in it....and heads/cam/intake.... and put it in the car so I can drive it. It has been down really since about August 2006....
I am also working on assembling another good engine...this time with girdle.... good crank and rods for my play motor.... and using the stock bottom end motor for a spare to just drive around in anyway...or in-between getting this new good motor built.
Was that long enough for you? whew!
