Oil Pump clearances and oil pressure

Discussion in 'Buick FAQ' started by LARRY70GS, Oct 24, 2017.

  1. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    A lot FAQs here have to do with oil pressure. Buick engines, other than the Nailheads have a front mounted oil pump. The pump is actually housed in the front aluminum timing cover. The pump consists of a pocket with 2 spinning gears. One gear is driven by the camshaft via the bottom of the distributor shaft. That gear drives the other gear which spins on a shaft inside the pocket. The 2 gears are what pump the oil. The pump pocket is aluminum, the gears are steel. As the engine warms up, the aluminum timing cover expands more than the rotating gears. This causes the internal clearances to increase, specifically, between the gear faces and the oil pump cover. This is called end clearance. If the end clearance is too large, too much oil will bypass the gears resulting in lower oil pressure. At the same time, the oil heats up as well, and that lowers oil viscosity, which also drops oil pressure. It is normal with any engine, for oil pressure to be high with a cold engine. Internal clearances inside the pump are lower, and the cold oil is thicker. It is normal for oil pressure to drop off as the engine and oil temperatures increase. This can be a problem in Buick engines if the oil pump is worn. Oil pressures can also be lowered by improper main, rod, and cam bearing clearances. Buick engines have tighter bearing clearances for a reason. Larger main and rod clearances can bleed off oil pressure, and the front mounted oil pump means that the engine is oiled front to rear, unlike other makes that have an oil pump that sits inside the oil pan. Excessive bearing clearances can cause a large difference in oil pressure from the front to the rear of the engine, possibly starving the rod bearings at the rear. This is why it is necessary to set up clearances when assembling a new Buick timing cover, or rebuilding an existing one. Back in the day, when new timing covers were not available, some guys would use the high volume/high pressure oil pump kit. The kit consisted of longer gears (1/4") and a spacer plate. This increased oil pressures and volume, but it also caused an increased load on the front of the engine. That can cause increased wear to the front cam bearing, timing chain and gears, and distributor drive gears. There are lots of guys who used these kits when nothing else was available, but it necessitated using proper caution with a cold engine and oil. These days, we have new timing covers available. The TA Performance cover is a great product, and Mike has incorporated many improvements over the stock cover. Highly recommended with any new engine build.

    http://www.taperformance.com/proddetail.asp?prod=TA_1533A

    As mentioned, the clearances inside the pump are critical to satisfactory oil pressures, especially when hot. The Buick chassis manuals have a section for measuring pump end clearance. When new, the pump gear faces should be above the timing cover gasket surface. The chassis manual has a picture illustrating the simplest way to measure this.
    OPendclrce.jpg

    While it is easiest to set the pump up with the timing cover off of the engine, it can be done with the timing cover installed. If the cover is off the engine, you can use a properly set up dial indicator to measure the end clearance. Setting the end clearance as tight as possible without the pump gears binding is the objective.

    The gears should be between .002" and .006" ABOVE the gasket surface. Preferred end clearance is .002"-.003". The end clearance can be adjusted by using different thickness gaskets. TA Performance markets an oil pump shim kit for this purpose.

    http://www.taperformance.com/proddetail.asp?prod=TA_1704

    Oil pump shim kit.jpg
    The gaskets are color coded for different thicknesses. As an example, if you measured the gear faces as .004" above the gasket surface, using a .006" gasket would give you the preferred .002" end clearance. Doing this properly is a must if you want the maximum hot oil pressure. As a side note, to get the engine and oil as hot as they will ever get requires driving the car at highway speeds for about 20 minutes. Idling the engine until the coolant temperatures have stabilized will not do it.

    What is the desired hot oil pressures for Buick engines? For the SBB and V-6, you want 10 psi/1000 RPM. That means if you want to shift the engine at 5500 RPM, you'll want to see at least 55 psi hot. For the BBB engines, you'll want 11-12 psi/1000 RPM. It is nice to have 15-20 psi at a hot idle in gear. Not all Buick engines will idle with pressure that high. Depending on the bearing clearances, some will idle lower. As long as the pressure goes up as engine RPM increases, you are fine. Years ago, I remember Denny Manner getting a question about satisfactory hot idle oil pressure in a 455. He replied jokingly, "anything above zero":D. While we all want to see more than zero, it can be lower than the 15-20 psi as long as you have sufficient pressure at the higher RPM that the engine will be operated at. Of course, you need a good oil pressure gauge to verify this. IMO, every Buick should have a real gauge. By the time you see an idiot light, you may be doing damage.

    There is another product that can help oil pressure across the board, especially at idle. It is the booster plate. The plate re routes oil inside the pump to make it more efficient. It is a good investment especially if you are rebuilding your existing oil pump. The booster plate also does two other things, it provides a new wear surface for the gears, and it also acts as a girdle, reducing the amount that the timing cover expands when hot. It can't hurt to use it, and it is cheap enough at 30.00.

    http://www.taperformance.com/proddetail.asp?prod=TA_1510

    The oil pump cover houses the oil pressure relief spring and valve. Spring pressure determines the maximum pressure the pump will produce, maximum pressure assuming pump clearances are normal. Current oil pump gear kits come with an assortment of springs and a new valve. This is what Mike Tomaszewski has to say about that. Copied and pasted from a post of his.

    "
    Folks,
    A few pointers here. First, The pump cover that comes with the TA pump assemblies is the new style. DO NOT install a white spring in this cover. The white spring in the newer cover will lock the relief valve shut This cover takes the shorter springs. You may use the stock spring from your original cover but other than that spring you must use the orange, yellow or green. A stock spring from 1978 say through 1987 would be the same as the orange. The original say 1964-1976 stock spring will give more pressure than the orange. Recently we have been providing both the original (steel color) and orange spring with the regulators. With the new style pump covers I have found that the yellow spring works very well and I have since been putting them in our pump assembly's. The green spring which some of you may have is not always in the kits. Now this spring will kick the upper end oil pressure higher. I would say when using this spring, use caution. Thinner oil, larger clearances, then maybe this spring would be the one. Now if you ever install one of these heavy springs and the pressure does not move up, chances are there is an internal problem in the engine. Bearing clearances, bad bearings, oversize lifter bore, gallery plug came out, wrong or bad lifter. Or pump set up way wrong.

    OilPumpInst.jpg

    Compatible Spring,
    CompatibleSpring.JPG
    Incompatible spring,
    IncompatibleSpring.JPG
    Just had a customer call having trouble getting oil pressure on a 350. He had purchased the high volume cover from us, which is not one we machine in house. This cover comes with the longer gears as a kit. After some conversation I started to get the feeling that he did not have the longer gears installed. When asked, he said he purchase the gears from Summit and there were no gears with the cover that came. I said they were in the box, do you still have the box. He went to the garage, found the box and what was at the bottom, the gear set. I never seen or heard of this before, but as you see, things happen.
    Back to the pumps. The tightest I have ever set one up knowingly has been .001. I recently set one up that was between .001-.0015, been awhile since I set one that tight, normally .002-.003. .004 is the loosest I will go. But because this one was between .001-.0015 I did some testing. I froze the timing cover assembly to see if it would tighten up. It still spun freely and when checked frozen it still had .0005 clearance. I have built 100's & 100's of these oil pumps over the past 35+ years, but sometimes I need to walk back over my prints just to make sure."
     
    Last edited: Apr 9, 2021
    Ken Robin, 33chifox, FLGS400 and 14 others like this.
  2. srb

    srb Well-Known Member

    Excellent post!
     
  3. tubecatgs

    tubecatgs Finally a 4 speed......

    Awesome Larry... thanks!
     
  4. Jim Blackwood

    Jim Blackwood Well-Known Member

    Great start! But of course there is more.
    Personally I lean towards the tighter end of the pump clearances for two reasons. The difference in thermal expansion that Mike mentions means the clearance opens up as the engine warms, and the cover flange is rarely perfectly parallel with the gear faces so you can have .0005" on one side and .003" on the other. Maybe not with TA's cover but stock, you will see this.

    Secondly, I would no longer ever set one of these up without doing some porting work first. It's easy, quick, and effective if you do no more than knock off the square corners and blend the radii back just a little. I also won't build one without the booster plate, and I port that too. The objective here is to smooth the flow and remove projections into the stream which can cause eddies. I also knock the sharp edges off the gears, just a very small deburr, enough to kill the sharp edge.

    Finally, all this is pointless unless you enlarge the suction galley and pickup, and tighten up the bearing clearances. I like to see .0010-.0015" on the bearings and 9/16-5/8" on the suction line. Be sure to use a piloted drill bit for that job.

    Jim
     
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  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Thanks Jim, I started this sticky thread so I can just link it the next time someone asks:), like the Power Timing thread. Post up any pictures you have illustrating what you do.
     
    Last edited: Oct 25, 2017
  6. JOE RIV 1

    JOE RIV 1 Well-Known Member

    thanks for your time!!
     
  7. ramzee1

    ramzee1 Well-Known Member

    should i check clearances b4 or after adding vaseline
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Before. Vaseline really has nothing to do with measurements. The factory specified using vaseline to ensure pump prime, but it really isn't necessary if you simply run the pump, after assembly, with a drill until the pump primes.
     
  9. BuickV8Mike

    BuickV8Mike SD Buick Fan

    Larry, I can't find the advise for which spring to use on a stock BBB?
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    If you want to spin it over 5000 RPM, use the white (60 psi) spring in a stock cover.
     
  11. OHC JOE

    OHC JOE Mullet Mafia since 2020

    Larry thank you for taking the time to write all this down nice and simple.
    This is why I use this forum AWESOME information and of course parts..:D
    It would have taken me a day to type this up.
    Thanks again for your helpful tips
     
    BuickV8Mike likes this.
  12. BuickV8Mike

    BuickV8Mike SD Buick Fan

    Thanks Larry, Easiest 50% performance gain ever!
     
  13. johnriv67

    johnriv67 Well-Known Member

    Where could I find a white spring? Or where do I buy a similar replacement?
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  15. johnriv67

    johnriv67 Well-Known Member

    Here's the question of the day, maybe the month.

    When assembling my 430 with TA oil pump booster plate, I prime the engine with my drill pump and the electric drill bogs down. However, when I let off the drill and remove it from the points distributor housing I'm using, the main pump shaft begins to slowly spin the other direction at a 1/4 a revolution per second.

    What could possibly be spinning the shaft the other direction as I try and build oil pressure within the engine? I talked to Tim at TA and he said that this is not normal.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Do you still have the adjustable regulator cranked all the way in? Sounds like you have a blockage somewhere.
     
  17. johnriv67

    johnriv67 Well-Known Member

    I don't have an adjustable regulator, just the stock 40 psi spring. Could the pressure relief valve be frozen inside the cover?
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Sounds like something is blocking flow. Are you sure you assembled everything correctly? I don't know why the relief valve would suddenly seize up, that isn't likely, rather it is something you did.
     
  19. johnriv67

    johnriv67 Well-Known Member

    I guess I did not, so I will be disassembling that while the engine is still outside the car. Glad this happened in the end. I'll update this as it goes...
     
  20. Bens99gtp

    Bens99gtp Well-Known Member

    is it possible it's just pressure still in the passages back feeding. normally the dist cant spin backwards when the motor turn off back of the cam gear...........but without them there the pressure still in the system will look for a way out.

    did you put a gauge to it when priming.........that's a must to know for certain pressure is built, with a 40psi spring a drill should be easily able to spring that up to reach full pressure.


    what happens if you stop the drill hold still for a minute then release does it still spin backwards.


    the priming tool summit sells for use of chevy motor will work on our motor too

    https://www.summitracing.com/parts/pro-66896/
     
    Waterboy and BuickV8Mike like this.

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