oil pump shimming

[chim326]

Can anybody tell me is it possible to shim the oil pressure relief valve as getting a ticking noise when engine gets to normal temprature on tickover. New cam, new lifters, new manifolds gaskets.(no leaks) and brand new short engine. 0.25" shims for preload on cam. oil pressure normally around 30 psi falling to 3-4 psi on tickover then the ticking starts. Not concerned with 30 psi at at mid range revs. But wondered if you can bring oil pressure up a couple of psi just to feed the top of the engine on tickover.
Thanks.

[that daddy]

mmmm trouble is on most engines the pump is not roatating fast enough to open the relief valve on tick/over much if any, shimming the relief valve normally as an effect as the revs rise,ie bleeding less oil, as the bearings resistance to pass oil increases as the pump pushes more oil the gauge pressure increases,did you renew the pump?

[boosted Ls1]

If you have thin oil it will be prone to making all sorts of lifter related noises. Exhaust gaskets can sometimes leak a bit as well.

Boosted.

[GreenV8S]

3-4 psi isn't good. What oil are you using?

[chim326]

just running in, crappy 20/50. did not change pump. thought 30 psi on 3000rpm revs was ok.

[GreenV8S]

20/50 should be OK. I think either the gauge is fibbing, or you have a well worn oil pump or other problem dropping the oil pressure. What was the pressure like before the work was done?

[brummiewedge]

IF the preload on the cam is not enough, then the tappets can return too far and clatter the clips, did you measure pre load? I have just added some pre load to mine as mine was tapping when hot even though oil pressure was ok. The trouble was that with the big valves cut in, there was 40 thou diff between the valve stem tops. I went too far for fear of valve lifter pump and when everything was hot it got one or two of them noisy. I dropped 20 thou out of the post shims and it is now fine. No probs with the lifters pumping either. I am at 40-80 thou preload now.

[chim326]

Prior to rebuild it was approx 25 psi @ 3000 rpm. Did a mechanicle oil pressure test last night and the recordings were 3.5 bar (49psi) when cold on tickover and 2.5 (35psi)when hot. Engine started tapping @ 2.7 bar. Seems like the gauge is f...... and the pump is ok. Lifters were shimmed between 40 - 80 thou. removed 20 thou from post shims and this helped as it was a bit ticky prior to the engine reaching it normal tempreture. This engine 4.0 has 1996 heads with a new cross bolted block and new Piper cam if it makes any differance. Thanks for prevous threads guys.