I just got a brand new GM timing cover in the mail along with a few other parts. And since beer drinking just screams out for measuring things, I got out the Digimatics.
I have a Fel-pro front cover gasket set and its oil pump gasket is .0075" think. The gasket that came with my Melling oil pump kit is only .006". Kind nice to have .0015 to adjust with. The Melling pump gears are both .8725" tall. And protrude .005 above my front cover. With no thermal changes or gasket crush that would give me .001" using the gasket that came with the gears. Granted the front cover does have some machining marks from the endmill that made the pocket. I'm guessing that'll give me another .0005"~001" of clearance. It's looking like the thicker Felpro gasket will be the one to use.
While deburring and porting the cover today, I noticed a few things about it. It has two low pressure inlet sides and the one smaller output hole. The high pressure outlet hole has a diameter of only .470". There's plenty of meat to take that one out to .500". (same as the hole in the gasket). The timing cover gasket blocks off the higher of the two intake holes. What's interesting is that the oil has to go in the lower hole from the pickup screen and go up past the higher one then make two 90* turns to go back down to the pump cavity. That little trip adds around 3/4" of height (and drop) the oil has to climb before seeing the pump cavity. It would seen that a straighter shot would be lots more efficient........
Which brings me to my next couple on things I've noticed.
First, why buy a new thrust plate? When the oil filter adaptor gets swirls in it, just resurface it. I've got mine sitting here next to me polished to a mirror shine and flat to 4microns. Why double the odds on having a leak there?
Second, on the front cover the oil has a pathway where it goes down and gets blocked off by the filter adaptor. On the Kenne-Bell instructions for the booster/thrust plate it says to grind a 1/4" deep trough to mate with the inlet oil passage. This seems like a great way to help the pump gears draw oil up from the pan. That would make some oil have to travel approx 3/4" less uphill to get to the pump. Since I'm not going to spend money on a booster plate, I'm thinking about making a little pathway to tap that oil reserve as soon as I get more beer.
Which brings me to another great idea that should work great and be even easier. On the pump cavity it's shaped somewhat like a figure8. There's a rough cast spot where the gears don't ride that's about 3/4" wide. A .500" hole right there would supplement the hell out of some oil right where the pump gears mesh looking for oil to pressurise. I'm going to give this one some more thought before I go drilling into my brand new cover. It's basically connection a low pressure oil path to the same low pressure oil path. The pump gets the fresh oil from the side of the gear teeth. It looks ALOT more efficient use of the gear teeth to introduce oil into the center (and/or top and bottom). The other side of the gear is fed by returning oil from the pressure bypass spring. I'm wondering just how much oil comes from there. If it's alot, it might cause some sort of reversion on the feed path from the pickup. Not sure on that part but I'll consider anything that might cut down on parasitic losses and take some load off my front cam bearing.
I was comparing the factory clearances on Steve's website and noticed a few more odd things. On the oil pump page, http://www.vortexbuicks-etc.com/Oilpump.htm ,there's some factory service specs posted there. And my new cover is out of spec on a few of the diminsions.
The pocket depth of the pump cavity is supposed to be .868"~.870". My new cover is .867". That doesn't bother me as I'm thinking at least .0005" is going to leave as the cover and pump bed in together. The dia of the pocket calls for 1.670"~1.675". I measured in a few places and got 1.6665"~1.6785". I was amazed at how those number came out. The factory only gives .005" plus or minus to be in spec and my brand new cover is both loose and tight(that last bit reminds me of a few hundred impure thoughts while imitating K-9 mating rituals).
I think tomorrow I'll try to find a roller cam button in stock and see about putting this thing back together. (after I finish match porting the waterpump to the cover that is!)
Earl
I have a Fel-pro front cover gasket set and its oil pump gasket is .0075" think. The gasket that came with my Melling oil pump kit is only .006". Kind nice to have .0015 to adjust with. The Melling pump gears are both .8725" tall. And protrude .005 above my front cover. With no thermal changes or gasket crush that would give me .001" using the gasket that came with the gears. Granted the front cover does have some machining marks from the endmill that made the pocket. I'm guessing that'll give me another .0005"~001" of clearance. It's looking like the thicker Felpro gasket will be the one to use.
While deburring and porting the cover today, I noticed a few things about it. It has two low pressure inlet sides and the one smaller output hole. The high pressure outlet hole has a diameter of only .470". There's plenty of meat to take that one out to .500". (same as the hole in the gasket). The timing cover gasket blocks off the higher of the two intake holes. What's interesting is that the oil has to go in the lower hole from the pickup screen and go up past the higher one then make two 90* turns to go back down to the pump cavity. That little trip adds around 3/4" of height (and drop) the oil has to climb before seeing the pump cavity. It would seen that a straighter shot would be lots more efficient........
Which brings me to my next couple on things I've noticed.
First, why buy a new thrust plate? When the oil filter adaptor gets swirls in it, just resurface it. I've got mine sitting here next to me polished to a mirror shine and flat to 4microns. Why double the odds on having a leak there?
Second, on the front cover the oil has a pathway where it goes down and gets blocked off by the filter adaptor. On the Kenne-Bell instructions for the booster/thrust plate it says to grind a 1/4" deep trough to mate with the inlet oil passage. This seems like a great way to help the pump gears draw oil up from the pan. That would make some oil have to travel approx 3/4" less uphill to get to the pump. Since I'm not going to spend money on a booster plate, I'm thinking about making a little pathway to tap that oil reserve as soon as I get more beer.
Which brings me to another great idea that should work great and be even easier. On the pump cavity it's shaped somewhat like a figure8. There's a rough cast spot where the gears don't ride that's about 3/4" wide. A .500" hole right there would supplement the hell out of some oil right where the pump gears mesh looking for oil to pressurise. I'm going to give this one some more thought before I go drilling into my brand new cover. It's basically connection a low pressure oil path to the same low pressure oil path. The pump gets the fresh oil from the side of the gear teeth. It looks ALOT more efficient use of the gear teeth to introduce oil into the center (and/or top and bottom). The other side of the gear is fed by returning oil from the pressure bypass spring. I'm wondering just how much oil comes from there. If it's alot, it might cause some sort of reversion on the feed path from the pickup. Not sure on that part but I'll consider anything that might cut down on parasitic losses and take some load off my front cam bearing.
I was comparing the factory clearances on Steve's website and noticed a few more odd things. On the oil pump page, http://www.vortexbuicks-etc.com/Oilpump.htm ,there's some factory service specs posted there. And my new cover is out of spec on a few of the diminsions.
The pocket depth of the pump cavity is supposed to be .868"~.870". My new cover is .867". That doesn't bother me as I'm thinking at least .0005" is going to leave as the cover and pump bed in together. The dia of the pocket calls for 1.670"~1.675". I measured in a few places and got 1.6665"~1.6785". I was amazed at how those number came out. The factory only gives .005" plus or minus to be in spec and my brand new cover is both loose and tight(that last bit reminds me of a few hundred impure thoughts while imitating K-9 mating rituals).
I think tomorrow I'll try to find a roller cam button in stock and see about putting this thing back together. (after I finish match porting the waterpump to the cover that is!)
Earl
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