I have a 1992 chevy k1500 with a new premium long block, 5.7 liter 350. The only used parts on the motor are the intake, exhaust manifolds, throttle body, ac compressor, map sensor, egr valve, and oil pan. I am having alot of very irriatating problems with this truck.
#1 when we first started engine , it was leaking oil behind distributor. It was coming out of the cap on the distributor. I replaced distributor, oilsending unit, and even pulled off intake and redid the gasket. Now oil has stopped leaking in rear and is leaking out of dip stick tube only sometimes and only when driving. I replaced the pcv and breather problem still not fixed. The engine only has 57 miles on it.
#2 the motor seems very sluggish. It does not run like a 350 , the motor i replaced had a cracked head and ran way better. The oil pressure never gets over 30 on factory gauge and at idle it is low. The valves come already adjusted on premium long block just wondering if they may not be adjusted right.
#3 motor will die if you cut on ac. Will not idle. All vacumm lines are hooked up and it runs solid with ac off. Engine makes no noises, no smoke, and sounds really good.
Please help me figure out what is going on i am about to pull my hair out.

 

Just a guess because it happened to me in the past but, could the distibutor be 180 degrees off? I had a 350 installed into a 69 camaro only to be terribly disappointed that it was slower than the 250 inline 6 cylinder it replaced. Then I started messing with the timing and found you couldn't rotate the distributor because it was too close to the fire wall. So we rotated my plug wirearound to make the difference and that did the trick. Bam, it ran like a 350. I know that was a lot older car and may not even be possible in a newer vehicle but it's worth a look. Good luck, and keep us posted if you find out what's wrong.

 

Timing is dead on , 1 degree off. I checked it 10 times and even put in a new distributor. Thanks for the info.

 

Come on guys please help me , I am out of ideas,