vehicle of concern is a 91 RS 305 tbi.
the vehicle is equipped with a electonic autometer oil press guage. the sendor of use came with the guage and replaced the stock sendor just above oil filter....

problem is at idle and engine is hot with fresh oil and filter (castrol GTX 10W30 & fram PH30 filter), PSI is about 19...
you will hear a slight lifter tap... you snap the throttle and the noise disapears... return to idle and noise gradually comes back.....

the lifters are a hydralic roller and are all adjusted properly. any input on this matter would be excellant thanks
LUKE

 

The right thing would be a high pressure oil pump, but I would just use a mellings m-77 and call it good. It's a big-block oil pump, so it takes a little more to operate, but has always proved dependable for me.

 

You don't want a high pressure pump. You *might* want a high volume pump. There is nothing wrong with 19 psi at a hot idle though. I would find the offending lifter and try tightening it up a bit.

 

I would ditch the fram and get an ac delco filter.

 

update, i found the offending lifter, exhaust lifter on cyl. 5. anywho i re-adjusted it and it still makes the noise, ill probably drop the pan and put a pump in it, can you remove the pan on one of these cars w/o pullling the engine?
thanks
LUKE

 

BUMP
on removing oil pan with/ out removing engine?......

 

You need to at least lift the engine to get the pan off. It won't come off as it sits, the counterweights are in the way. It will not be a fun job. I'd replace the filter first (with a quality one) and then the lifter if you still have problems. From what you said, you don't really have an oil pressure problem.

 

ok bro, thanks for the info, i figured the problem lies elseware, ie: the lifter. of concern.
and i also figured i would at least need to "rock" the engine to one side to get more access to the pan and to drop it down some.

 

me and a buddy dropped the oil pan on my 91 z vert last winter. It is possible to do this with the engine still in the car. You'll have to remove the bolts from the motor mounts and lift it up a tad, either with a hoist or jack.

For the crank counterwights, the factory service manual has a specific procedure for rotating the engine to a certain point that will move all the weights up into the block, so you barely have to lift the engine and it slides right out. When I get off work here, I'll see if I can find it and post it up.

 

IIRC, the timing mark on the balancer should be pointing at the 6'oclock position.

I removed the pan on my 83 with the motor still in the car, it wasn't that hard. I used a jack with a block of wood under the balancer to lift the motor. Took me a couple tries to get it back in without disturbing the gasket. Be sure to remove the distributor cap when you lift the motor. It could hit the firewall and crack.

 

IMO and with due respect, I think installing another oil pump is a waste of time. If the valve train is adjusted properly I would think that if your problem is oil pressure related, more than one lifter would be noisy.

19 psi at idle (hot) is plenty of oil pressure. The Fram is ok (perhaps not the best constructed filter out there, but it'll do).

Do you hear the noise when the engine is cold?

I would look at the offending lifter before dropping the oil pan. It sounds like it's bleeding down more than it should. Did you remove the rocker arm and push rod to examine for excessive wear?

For me, an intake manifold R&R is much easier than an in-the-car oil pan R&R.