i have a 89 mustang LX. just dropped in a .30 over 351 windsor. it has blue ridge 1.6 roller rockers, pushrod guide plates, Lunati bracketmaster 2 cam thats 512 lift. ported, polished and milled 302 heads with bigger valves. flat tappet cam btew with lifters. It started idling at 40-50 psi now it drives at 2000rpm at 5-10 psi. what causes this. the valves need adjusted, but what else cause it? i drove it 25 miles this way and then parked it and wont drive it till i fix it. it also has long tube headers, msd ignition and all that. all help appreciated.

 

5-10 is not enough as you already know, my stock oil pump on my rebuilt 351w in my old bronco cranks out 25-30 at idle when hot, a common oops when rebuilding a motor is forgetting to reinstall the oil galley plugs or forgetting to tighten them. with a missing galley plug you will have next to no oil pressure. if you forgot the rear galley plugs you would have a MAJOR oil leak at the bellhousing, to check the front galley plugs the timing cover must come off, also if a main or rod bearing has too much clearance itll bleed off oil pressure,i hate to say it but the motor has to come apart again to see whats goin on or itll come apart all by itself if you know what i mean.if it was me id remove the intake/ valve covers and timing cover and using a oil pump primer spin the oil pump and watch for any hemmoraging(spelling) of oil anywhere, the valvetrain should get even amounts of oil flow on both banks, if everything looks good up top then you have to pull the motor and check out the bottom end, just so you know oil pumps themselves rarely fail. its almost always something else that causes an oil pressure problem. good luck.

 

Normally low oil pressure is due to cam bearings, on any engine. Like the previous guy said, strip the thing down, check all the bearing and clearances, including all the cam bearings, and see what's going on.

 

First,change the oil pressure gauge and line. Second try a different oil filter if you are using a Fram.What weight oil are you running.Does the valvetrain make alot of noise.