i have a 78' ford f150 with a 400m engine and i had a cam go flat in my truck, so i replaced it with a 252-h compcamsand lfter set, i also replaced the timing chain with a non-retarded one.when i got the motor fired up, i had no oil pressure and the lifters wouldnot pump up, so i went to the parts store and bought ahi-volume/hi-pressure pump, my friend told me to check my main bearings while i had the pan dropped. i did and found the crank was severly scored.i had a friend that was parting out his 78' bronco, and i bought the 400m from him. it was completely stock and he drove it into the shop before we pulled the motor. i got it home and installed the rebuilt heads off my previous motor, the new cam, lifters, timing chain, and hi-volume oil pump. i have also installed new rod and main bearings and they are within factory specs. i have also installed the oil pressure line from the front to the sending unit, and i can not get any oil pressure reading. i have both a factory and a mechanical gauge that i have swapped twice to verify that it is correct. i pulled the oil filter and cranked it over and oil gushes out like crazy. and i have also pulled the sending unit and now oil comes pouring out of there like crazy too. but i still have no oil pressure. i pulled both valve covers and i have absolutly no oil coming to the top end of the motor. what is wrong with this thing!?!?!?

 

i just heard from a guy on another board that my lifters arent pumped up and i need to loosen the rockers just a bit, run for a couple minutes then torque down while engine is running, does that make any sense?

 

is your pickup too high in the pan??

 

i already checked that it is a 1/4" off the bottom, i pulled th oil filter and it is gushing out when cranked so its not a pump problem

 

Rebuilt heads? How much was milled from the deck surface? I'm thinking that these heads installed on two engines resulted in both engines not having good oil pressure. I'm wondering if the preload is too much on the lifters and the oil cannot pass through the lifter gallery. If that is the case you need some shorter pushrods.

 

sorry i forgot to post up.....i found the problem and it ended up being the wrong lifters the guy at the parts store gave me lifters that were too small in diameter