oil pressure concerns

I'm a little concerned about oil pressure.
I run a 5 stage missile dry sump pump with 14.6 quarts of brad Penn 70.
At initial start up it pegs 100lb gauge. Probably 115lbs.
As it warms up to 180 degrees my oil pressure slowly drops to 70, 60, 50, eventually going to 30 to 40 lbs at 2500 rpm idle or Cruz speed.
I do street drive it.
Is my block growing enough to increase block to main clearance? Do I need to tighten up main clearances to solve this problem.
Can't get spring any tighter on pump.
Thanks guys

 

How about the particulars on your engine --- oil type and brand ---main bearing clearances ----- any past block damage that was repaired -- etc etc

 

No damage or repairs. Bryant crank, b2 rods, stageIV heads not bad.
Oiling through pushrods.
AVERAGE ON MAINS .0054 / .006
Journals 2.7460 to 2.7462
Dmpe k 11 1-1 on street 11.6.1 Ross pistons.

 

Some years ago I did a line hone on a billet aluminum block, got it perfect at the shop and they offered to clean the block in the Storm Vulcan. It heats the block to about 300 degrees as it is washed. I had them remeasure the case bore we had just finished honing when we brought it out of the storm vulcan......the main case bore had grown .003 thou in the heat from washing. So your .006 clearance is probably growing to .009 and it is leaking oil like a river from the main bearings. Just relating what I saw, and I was shocked at how much a bit of heat increased the clearance.
Good luck with your project. Jeff Johnsen

 

Ditto with the post above --- again, what oil do you run ? It makes a difference .

 

so did the block not shrink back?. Wow

 

Oil Pressure

The oil cannot drain back on a supercharged roots style motor so at the drags we have a road called the return road where it does drain back with the motor off . If you ran in Bonneville you would need 25 to 35 gallons to complete the run safely . Shut the motor off .....wait 5 mins and restart .....it will run a short time until its out of oil again ....where is it ?? ....in the right hand valve cover of course ....right where you should expect it to be .

 

He has a 5 stage pump , is he pulling off the heads with a scavenge line ?

 

Yes but have only been pulling off left head. Should I y them together and pull of both.

 

The even side head would be preferred----the post about the block growing with heat is expaining that the clearances increase when hot and come back when cold ---is this a alky deal or gas ?

Is it cooled at all ? radiator ? You could type a few more details -----the other thing is you need to get a 200 psi gauge--

If you are maxing it out with a 100 psi gauge what will happen soon is the gauge won't read right at any pressure --

The gauge range should be that you use the upper third of the range and not max it out --

 

Yes, when it cools back down to room temp it will measure back at the original line hone bore diameter. When you run it again it will open up again. Think about your cold valve set to hot valve set numbers. Also think about the loss of viscosity of cold oil to hot. When you add the 2 factors together you get a fair change in the oil pressure. When I went to shop class they told me that 2 things kept the crank off the bearings; pressure and viscosity. Today one must add high tech additives to the list but the essential truth is still there.
Jeff Johnsen

 

what additive do you use that's compatible with brad Penn.

 

Just use Redline and you won't need to mess with additives.

 

what additive do you use that's compatible with brad Penn.

 

Lucas heavy duty oil stabilizer has worked for me like a charm. One quart of Lucas and 14 qt's of Valvoline 60 weight.

 

So what does it do? Keep oil thicker when it heats up.

 

Yes and it keeps the oil on the rockers and other engine parts for weeks between races. I've never tried more but two quarts might be even better. I boil my oil after every weekend and change it after three weekends.

 

Do you know what the output of the pump is in GPM

 

No but canter might. They make a few different pressure section sizes.
Mine is not the old razor missile pump.

 

So how much should I close up main bearing clearances?