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blackgn231

Money pit
Joined
Mar 28, 2007
Messages
493
I have tried plastigage and the feeler gage method with out a gasket and with a gasket . I am feet different readings every time . It’s driving me crazy . My motor is installed in the car had a oil leak so took the adapter apart to replace the gasket . . Do you need to take the reading on the drive gear ? When I use a straight edge across the gears the idler gear seems to still have play a little up and down . But drive gear is tight . Is there any other way to do this ? Tried .005 , 007 and .008 and with plastigage it does seem to be tight enough to get .002 clearance . I really need help with this .
 
I had a similar situation as yours. My heat soaked idle oil pressure was terrible, 6lbs with 20-50 oil. By the way this does not really mean anything as long as past idle it makes at or over the 10lbs per 1000rpm (mine was well over).

That being said it bothered me so I removed the pump cover. The cover and cover side of both gears were badly scored. The pump cover had 2 gaskets on it so I lapped the cover smooth and the two gear faces. With one gasket on the cover I kept assembling with plastigage until I had .002-.003 on the drive gear, but I lapped too much off of the idler gear. Idler gear was at about .006.

Figured I screwed up but it turned out fine. I now have 11lbs at heat soaked idle with 10-30 oil so big improvement even with the idler gear clearance off.

When you are confident you have the drive gear at .002 smooth out the gear face edges so they do not feel sharp. After you assemble it make sure that you can turn the gears easily, it should not feel like it's binding at all (very important).
 
I had a similar situation as yours. My heat soaked idle oil pressure was terrible, 6lbs with 20-50 oil. By the way this does not really mean anything as long as past idle it makes at or over the 10lbs per 1000rpm (mine was well over).

That being said it bothered me so I removed the pump cover. The cover and cover side of both gears were badly scored. The pump cover had 2 gaskets on it so I lapped the cover smooth and the two gear faces. With one gasket on the cover I kept assembling with plastigage until I had .002-.003 on the drive gear, but I lapped too much off of the idler gear. Idler gear was at about .006.

Figured I screwed up but it turned out fine. I now have 11lbs at heat soaked idle with 10-30 oil so big improvement even with the idler gear clearance off.

When you are confident you have the drive gear at .002 smooth out the gear face edges so they do not feel sharp. After you assemble it make sure that you can turn the gears easily, it should not feel like it's binding at all (very important).
Very good advice. And don't forget to pack the gears with petroleum jelly.
 
Well I measured the cavity depth and it’s at the max .870 so it’s going to take around a .005 gasket since I don’t think I can find a .004 gasket a .005 will give me a .003 clearance.
 
Not being a Machinist myself, Mine was showing 10@ hot Idle & ~ 25 @ 3000 rpm . Researched & discovered that the OEM covers & thrust plate were very soft & prone too scoring. Mine was that way , with ~ 17000 miles on it. I installed the Melling P-201 kit & now she's 20 @ hot Idle & 40 @ ~ 3000. Only way to go , IMHO.
20211106_125636.jpg
P.S. The red lint is from a shop rag that was thoroughly cleaned before the filter was installed.
Also, like Hahny says..... pack the whole assembly with Vaseline , before starting up.
 
When I use a straight edge across the gears the idler gear seems to still have play a little up and down .

Sounds like you have a Chinese cover. They have the gear pocket deeper so the gears sit below flush. That way they're idiot proof and the pump can be locked up by accident. A GM cover would have the gears sitting above the surface.
 
It’s installed in the car so that’s not a option . The cavity is .870 and gears are .0872 for a .005 gasket puts a .003 clearance .
 
im pretty sure you want no more then a 1 tho of clearance I could be wrong don’t hold me to it
 
send to earl and have it blueprinted you will better off there is machine work that has to be done so don’t run your self around the block
 
Oh lord no. I won't lay hands on a chinese cover. They're not worth the risk.
 
I thought 0.002”to 0.003” gear end to pump housing clearance was acceptable ?
 
I'm sure that will work, but that's waaaay looser than I leave them. Keep in mind, aluminum expands right at double the rate of iron.

So the depth of the gear pocket will grow twice as much as the gear itself when the engine gets up to temp.
 
I'm sure that will work, but that's waaaay looser than I leave them. Keep in mind, aluminum expands right at double the rate of iron.

So the depth of the gear pocket will grow twice as much as the gear itself when the engine gets up to temp.
What is your preferred "sweet spot" on the clearance?
 
I shoot for .002-.003" gear end clearance.
TA sells a packet of gaskets/shims that can be used to dial in the end clearance.

I cross drill the idler gear, glass bead the gears, and lap them on a surface plate. I run a 1/4-20 tap through the holes that mount the adapter to the cover. I use oil on the bolts and torque them with an inch/pound torque wrench. Overtorque or undertorque will mess with your end clearance.

I always buy Melling replacement gear kits and have had good luck with them. The aftermarket front covers can be problematic. You are much better off with a good GM cover. No HV gears are needed if the pump is blueprinted and setup properly.
 
Well got it back together have good oil pressure but still leaking in the same spot . It’s leaking right at one of the bolts took the bolt out crank the car up leaked just the same soaked the gaskets in oil first before installing them . Not sure why this is happening it was good for a long time then just started leaking . Guess will take it apart again and see what’s going on with the gasket .
 
Well got it back together have good oil pressure but still leaking in the same spot . It’s leaking right at one of the bolts took the bolt out crank the car up leaked just the same soaked the gaskets in oil first before installing them . Not sure why this is happening it was good for a long time then just started leaking . Guess will take it apart again and see what’s going on with the gasket .
something is not flat, and soaking them in oil isn't needed either.
 
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