oil pressure issues

Hi

I am new to this board as a writer i have been lurking around for some time tho.

I have some odd oil pressue problems that i can't seem to find a solution to, i hope you guys might have some idears about it

The engine is a cbb 555 mark IV block filled, dart heads, littlefield 14/71, callies crank, venolia rods and pistons

When we start the engine the oil pressue spikes to over 70 psi, then when the oil and engine heats up, is falls to 40 psi. But here is the odd thing if i then rev the engine (either slowly or fast) the oil pressure drops 5 - 10 psi, it dosen't climb like it should.

I sent the crank and rods out to be prof. checked and the crank polished, the clearances comes out to 0.0028 on the rods and 0.0034 on the mains, big ends on the rods are all fine.

We have tried different oils and filters but still no change.
We normaly run a high grade 50 wt oil or we run kendall 70 nitro oil depending on the ambient temp.
When i take the pan off the oil looks fine with very little alcohol in it. On every test we of course try with new oil.

I have tried changing the oil pump, and bearings still no change. The oil pump is a hi pressure hi volume unit.
The oil pan is a 8 qrt mildon, i have recheck the pan to pick clearance and it comes out to 13 mm (just over half an inch to you guys).

Sorry for the long rant, but i just wanted to include all info.

Sune Larsen from Denmark

 

oil pressure

What kind of filtering system do you use? We Have had issues in our funny turned out to be the filter.. may not apply to your situation just taking a stab at it.We tried thr fram upright style and it turns out u need to change them about every race if you run alcohol. paper saturates and expands if it sits.
our bad we did not know. we just put a system one canister with a cleanable screen and we hope problem solved.

 

we use the standard filter location on the block.

Yes the engine was great when i bought it. I then had to tear it down after i broke a lash cap. My oil problems started after this. During this first tear down, i did change the oil pump, among other things. So Mike you might be on to something here. Eventho the pickup oil pump interference fir seems good to me.

 

Do you run a vacuum pump on the motor?

Blessings.........Ron.

 

no, no vacum pump.

 

Tig weld your pickup to the oil pump, just a few tacks around the tube. Also check to see how much clearance your pickup has between the pan. It could be to close to the pan and also causing cavitation.

 

I had a similar problem when running a low flow oil filter.Switched to the wix racing filter. Had a rod bearing go away once and oil pressure also went down when I reved it.

 

Did you put screens in the lifter valley? is the oil returning to the pan fast enough?

 

oil

Is it possible that you have an internal leak. Like a loose lifter from the valve train rattles or maybe the distributor body just above the gear?

 

First of all thanks for all the replies!

about the oil level, the oil pan is a 8 qrt pan and we run 9 liters in motor.

The engine dosen't have screens in the lifter vally.

The engine dosen't use a standard distributor, instead we run a msd plug and front mallroy dist. The msd plug is brand new. I went over all the lifter last time i tore it down they all seemed in great condition.

picukup to pan clearance is 13mm (alittle over half an inch)

I had a spare pump laying on the self, so yesterday we changed it. It seems that the problem is pump related. because now the engine idels with just over 70 psi oil pressure and the pressure climbs with the engine rpm. But now when the engine is hot, but not running i can only produce 10 psi oil pressure by turning the engine with the starter motor. when it is cold i can make over 60 psi on the starter alone. weird...

So tomorrow i guess i'll pull the pump and tig the pickup and see if that helps. eventho it is also secured by one of the oil pump cover bolts.

 

yeah i swapped the pickup/tube assembly from the old pump to the new one.

 

oil pumps

I didnt see what type pump you use. you said a high pressure/high volume pump. if it similar to a stock type you should throw it out. try a tilton or such. get a pump for a blown engine, not stock stuff. been there done that

 

Yep, that is my thoughts too at the moment, so I have just ordered the moroso 22167 gerotor pump. As i understand it, it is a supiour pump in all ways, it flows more oil at higher pressure, with less cavitation, and it has no external pickup that can fail or leak.

again thanks for alle the replies.