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Oil Pump / Timing Cover

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TurboWh1

Well-Known Member
Joined
Aug 12, 2002
Messages
1,161
Does anybody know what the tolerance is between the oil pump gears and the timing cover? I will be using a thrust plate to address the wear on the oil filter elbow. The surface on my timing cover is slightly damaged from who knows what and I plan to fly cut this on a Bridgeport.The timing cover probably needs .0010-.0015 taken off to clean it up. In doing this, I may need to fly cut the mating surface on the oil pump gears as well.
 

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My $.02.... Talk to Earl Brown, and get 1 of his covers..IMO, If those scratches and that gouge are as deep as they appear, that one is pretty much junk.
 
I can make this one work if I know what the specs are. I will reach out to Earl. I'd like to repair what I have versus buying new. I have a new TA performance cover I could throw on it but trying to keep car all original.
 
Gear side to cavity clearance is .002-.005. I like at a maximum .004. Gear end play is .002-.006. Those are the factory specs. Gear end play really needs to be .0015-.002. Many oil pump housings are not square to the gears, so squaring it up is a good idea. Oil pump gaskets vary in thickness. If you can't get enough end play, TA Performance has a gasket kit with varying thickness gaskets. If you are only removing .001-.0015, a stock gasket may be perfect.
 
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Gear side to cavity clearance is .002-.005. I like at a maximum .004. Gear end play is .002-.006. Those are the factory specs. Gear end play really needs to be .0015-.002. Many oil pump housings are not square to the gears, so squaring it up is a good idea. Oil pump gaskets vary in thickness. If you can't get enough end play, TA Performance has a gasket kit with varying thickness gaskets. If you are only removing .001-.0015, a stock gasket may be perfect.
Do this and you will be all set. The assembly line covers are usually better on the gear to pocket clearance.
 
Gear side to cavity clearance is .002-.005. I like at a maximum .004. Gear end play is .002-.006. Those are the factory specs. Gear end play really needs to be .0015-.002. Many oil pump housings are not square to the gears, so squaring it up is a good idea. Oil pump gaskets vary in thickness. If you can't get enough end play, TA Performance has a gasket kit with varying thickness gaskets. If you are only removing .001-.0015, a stock gasket may be perfect.

Excellent! Thank you, that is what I need
 
That TA kit isn't gaskets, they're plastic shims. I ordered a set a long time ago and relocated them to the trash can instead of even thinking about putting them on an engine.

It's hard to tell how good or bad your gasket surface is based on your pictures. I know how deceiving looks can be .vs real life with that stuff.

Personally if you're good enough to run a mill, you should be good enough to 'run' a surface plate. I'd start there.

The way I would do it is to first get a countersink and bevel all 6 threaded holes to spread out the load. Then make a few passes with something around 100 to 150 grit. Since lapping follows the hell out of the 80/20 rule, you'll be able to see what's going on pretty quickly. Then go from there. It's nice to have the entire thing nice and flat and square but that might not be in the cards. The part that REALLY need to be true and free of flaws is the section around the oil feel hole going to the engine. Leave a channel there and you've got a squinter (and not the good kind :D )


If you just have to absolutely positivity have to fire up the Bridgeport, you might end up going backwards. There's no reason to indicate of the gasket surface for your set up. You need to be PERFECTLY (as possible) square with your (worn) pump shaft bore. In an ideal world (ha ha) when that's trued in, you'll just happen to be square with the bottom of the gear pocket and the walls of the pocket will be indicated in at all axis.

If it takes a couple passes to get the feed and speed dialed in to leave a good finish, you might have just made your pump gears proprietary. from that point on. With a GM cover, the gears stick up above the gasket surface and the gasket make up the free play. The more chips you make, the more the gears will be out of the hole. The easy way is double up on the gaskets to keep from locking the pump up.... The correct way is to make the gears shorter.

I know for a fact you can get some beers and lap a thou or two off the gears, but I've never tried to machine therm. If you have a good set that might require a surface grinder to keep things right.... then some lapping.

If the gaskets surface has been lowered a lot, you'll want to fit the drive gear first, make sure it cleans on a fully torqued gasket that's had time to sit and take a set... THEN do the other gear and repeat the test with set time again.

There's a lot more to that surface than just a place to put a gasket and tighten some stuff down :D

After all that, you'll probably be good and fluid tight. The cover will still have the blemishes in the walls of the gear pocket but there's nothing that can be done for that short of serious heroics.


To answer your clearance questions, the best clearance is as tight as you can get it without having metal to metal. Thanks to thermal expansion of aluminum being right at double of iron, the clearances open up as the engine warms up.
 
One thing I have always done on front covers is put Helicoils in all the filter adapter holes. This allows the filter adapter to be torqued to specs without stripping out the threads, especially on an older cover. Never had a pump leak at the gaskets or shims.
 
I was able to achieve great results by lapping the gears with a surface plate and cleaning up the timing cover as well. The cover didn’t need much to address the gasket surface either. I probably took off .0015-.002 The pockets in the timing cover were much better than they originally looked. Just cleaned off the high spots.
 
Something I did a while back.
Its posted in another thread on this board as wel.
Clearly a perpendicularity issue.

IMO . . .
The oil supply is the mechanical achilles heel of the Buick V6. Lol

Pump Measurements.jpg
 
Sure was Earl
The gears were off as well though. Took me 2 weeks to get it right and I was about 30 minutes away from ordering one of your covers . . . . Lol
 
I give you credit for trying! The gears are above flush on GM covers and it takes the gasket to make the clearance (for those that don't know that :) ).

I have about 200 .0015" ish gaskets that I should market for the offshore units that are out of spec even without a gasket. lol
 
I just noticed your driven gear in the pic is upside down too. The stamps are supposed to go on the same side. Not all of them face down, some of them are up as well.
 
Thanks Earl.
Learned something new.

Fwiw . . . For the OP
It required a few files, a micrometer, and measuring many many times over till it to my liking. Much easier to get one from Earl. Your sanity and hair will thank you. Lol
 
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Factory spec is 10 ft. lb, but I would go less on an older used cover unless the threads are helicoiled.
 
I'm surprised it's not in inch lbs. Yeah mine is pretty new and I took it off not realizing it didn't need to come apart

Sent from my SM-G900V using Tapatalk
 
They're 1/4-20 threads with a good bit of engagement. They can handle a lot more than it seems.


Keep in mind lots of people use carb plates with (4)1/4-20's to pick up iron chebby V8s and the filter adapter has 6 fasteners holding it down.
 
I don't trust carb plates, though most manifolds have 5/16-18 threads. Guys on TV pull engines and transmissions at the same time using them. Three point chains and big bolts make me feel better.
 
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