Here are my thoughts on Volume and Pressure copied from another thread. "AFAIK, volume and pressure go hand in hand. If you try to push more volume into a confined space, you get pressure. If you have a leak in that confined space, you lose pressure. Bigger leaks, more pressure loss. Bigger confined space, needs more volume to generate the same pressure. Think of the confined space as oil passageways, and the leaks as oil hemorrhage from said clearances (including excessive oil pump end clearance). If the oil pump cannot generate sufficient volume to make the needed pressure, then your clearances are too large and/or you are hemorrhaging too much oil, hence the need for the HV/HP pump gears to generate MORE volume with bigger bearing clearances to generate sufficient pressures. That's the way I understand it anyway. If I am wrong, I'm sure the engineers out there will correct me."
I'm with the rest, and I'm no SBB guru. Oil pressure and volume is what we need, but have to be careful of the toll it takes on the driven parts, distributor and cam gears. Devon
I would think Steve’s pan will solve your issues. I have one for my build and must say it’s a nice piece. Adding an oil accumulator would also be added protection. Oil pressure dropping like yours does causes bearing damage.
This is why I concentrate on two things: First the bearing clearances, and I have to say, if your bearing and pump clearances are near the tight end of the Buick factory approved range you can have the same oil pressure as a fresh engine out of the factory did. Second, the suction side of the pump. At best the suction side has 16psi of pressure pushing the oil into the pump, and that is if the pump is producing a perfect vacuum at sea level on a very cold and muggy day. There is absolutely no way that can keep up with a 60psi discharge unless bearing clearances are tight and/or the suction passages have been enlarged. So if clearances are a bit large you are going to cavitate the pump. Just no way to avoid it, which is why heavier oil is a band-aid at best. Jim
You have something going on, bearing clearances maybe. My oil pressure gage moves up swiftly like my tach. I'm running tighter clearances like Jim Blackwood suggests. Try no filter like John runs and see if it might be the bottle neck for your pressure drop issue.... There's nothing to the allen bolt trick. 1/4-20 short cap screw inside spring on cap end. Full length head increased my o/p 15lbs. Half of cap head ground off gave me 7lb increase.
It's a long read, but sometimes my fingers don't know when to shut up... (because I spent too much time working on aircraft, and this ties to aircraft hydraulics systems and engine oiling systems, and all of it just clutters my brain) In a closed system, (typically) you have reservoir and circuit. The reservoir is (typically) unpressurised, the pump, relief valve, and components (all the other parts of the pressurized system the produce work from or acting against pressure, to include check valves, control valves, actuators, accumulators, controls). In the Buick latter V8 engine, the oil pan, pickup tube, the suction passage to the pump, the valley and the valve covers are unpressurized portion of the system. So, the crank, cam and lifters, and valve train (think, externally) are basically "in the sump" and benefit from lubrication/cooling by splash. The remainder of the oil passages from the pump, filter, to #1 cam bearing and galleries, through the feed passages to cam and main journals, rod bearings, and through lifters/pushrods to valvetrain, or passages to valve train are the "pressure side". The filter is very important, since it is "in line" of the hydraulic circuit, it can create an unexpected restriction if it is a poor designed filter, or has failure that creates unexpected high restriction, odd pressure changes over the engine's "normal" pressure readings over all RPM and loads, fluttering oil needle, or anything out of the ordinary, especially a recent oil change. All the areas that oil leaves the pressurized circuit are "returns to sump", and the points of pressure loss. When all components are correctly clearance, these "points of pressure loss" are factored as "relief valve" in theory/operation. They are key and considered in the overall of the system and operation. Since that is a big portion of the resistance, the pump clearances, all bearing clearances, lifters, (both bore and internal components unless solid lifters, valve train and gallery plugs are vital to the required resistance to facilitate correct pressure. With all of the listed "returns" having the same clearances: One engine, having smaller passages will result in higher pressures but lower volume. And another engine with larger passages will have lower pressure with higher volume. Controlling the pressure to the same operating pressure(s) over same RMP, using the relief valve, in concert with the "controlled returns" (leakage by clearances) will result in both engines having the same pressures, but different volume flow. And that is the crucial part. The higher volume at same system/operating pressures will facilitate higher oil supply that cools, and lubricates as well as "dampens" any spikes in any of the places that are crucial to pressure loss, even for a moment. The engine bearings (journal bearing) are thin film sliding bearings and by design, the oil what carries (bears) the load, the journals and the pins are not designed to be in direct contact with the sliding bearing surfaces, but carried by the oil film. (Hydrostatic lift, via oil wedge and hydrodynamic film). The film has to be able to shear (the hydrodynamic component of operation) to facility "replacement" of oil continually, to provide cooling, as well as maintain constant viscosity. (continual replenishment) If clearances are too large, or oil is incorrect viscosity, and/or "broken down" (fuel dilution, too high mileage, too old, contamination or overheated) journal "whirling' can occur where the journal becomes eccentric in movement within the clearance and bearing circle, this is also tied to engine rotation and harmonics and load/unload cycle. This is will allow the pin/journal contact the metal bearing, and lead to damage, (wiped bearings). All of this is why the entire system and all components are key to engine longevity and ability to produce and sustain greater power and work. Girdles, filled blocks, crankshaft enhancement, better stud/bolts and whatnot, all contribute to better hydraulics and result in stronger running engines that last longer. Newer engine designs factor all of this and now we see engines putting out tremendous power and can run nearly 1/2 a million miles. Mechanical Engineering is pretty danged cool. (OK, my fingers are getting stiff, and your eyes are probably bleeding, so I'll stop...)
. Had the same issue on my old build. My pressure gauge is like a tach. also, goes right up with rpm. Hopefully my new SRE pan will solve the issue, then with my aluminum heads I'll be making so much power I wont have to worry 'bout oil pressure, LOLOL
I like how GS Johnny checks his oil pressure annually and then forgets about it for the season lol! there's a dipstick on it, besides the owner, and i do check the oil for smell...once in a while. that's it. change it every other year. amsoil rep just shakes his head. fwiw, i have spent about 25k(some parts are not replaceable) in this engine since i started the 350 project. it gets treated like a $100 engine. again, if you build it right it will last a long time
Maybe clearances too much last build too. I don't have the dropping o/p at high rpm with stock pan & 5/8 pickup. No booster plate,, no adj regulator, no H.V. gears. Oh and plain old AC PF24 filters. Hope you find out what's going on.
Its strange for sure, clearances were good on last build too, even had the standard pump on last build Yeah I just use the standard oil filters too, wonder what gsjohnny's filter delete set up looks like?
Knowing how John likes using his Kentucky windage, probably an aircraft aluminum plate over the pump gears.
got no pics of cover. blame dano, he was here. food for thought; the t/c is a junk design with junk material. after many heat cycles and excessive rpms, the dist bore stretches'. this makes the cam/dist gear wobble and wear (maybe an overbore and steel sleeve is possible). but not a good design. this design has too many things that can/will go wrong. case in point, when i raced my 73, way back, w/pumps would go away. sealed power came out with cast iron ones. issue gone. still have that pump. now if somebody could make a turbo v6 gear pump cover for a dist style 350, that would alleviate some issues. open for discussion
Someone on here was looking to buy or bought one, but I looked at it and IIRC there was something different about the water ports or something like that. Always wondered why Buick didnt use an iron liner for the oil pump.
This weaver belt driven pump should solve any oiling issues. It will pull directly from the pan and feed into the factory inlet, SRE baffled pan.
