Boring oil pump stuff

[G B.]

Awhile back I questioned the adequacy of the stock oiling system design of sixties big blocks. A few folks were kind enough to respond. Here is some more info for those of you who are interested.

I investigated the points brought up by others on the Board. Yes, GM has changed the big block oiling system design over the years. At least two of these changes increased volume to the rockers. The first time was in late '66 when they went to a groove behind the rear cam bearing (rather than in the rear cam journal) to route more oil to the lifter gallery(s). The second volume increase was caused by going to 1.3" tall gears in the standard oil pump (rather than 1.1" tall) when the Gen V big block was introduced around 1990. Previously only the ZL1/LS7 (and maybe the L88?) oil pump had the taller gears.

Clem brought up the high oil flow rate he had observed at the rockers in mechanical lifter big blocks. This suggests that hydraulic lifter orifice size could be critical. However, I haven't found any hydraulic lifter design that is promoted as sending more flow to the push rod. I'm still checking the aftermarket.

I'm going to use the higher volume GM oil pump for '65 - '74 BB Corvette pans, #3969870. Since this pump only puts out the "standard" oil volume for Gen V and VI big blocks, I don't think it will harm a 1970 454.

I'm still interested in suggestions from others though. I guess I'm surprised that more of you haven't had to overcome the seized valves, scored rocker balls, and bent push rods that I remember from the seventies when these BB cars had about 50,000 miles on them.

[Joe L.]

Re: Boring oil pump stuff

Jerry------

The GM #3969870 oil pump is the ZL-1 oil pump and it does have the 1.3" gears. This pump will work just fine in most big blocks. It comes complete with a tack-welded oil pump pick-up which is positioned to work perfectly with any stock 65-74 Corvette oil pan. It has to be re-positioned for most other oil pans, though.

The L-88 oil pump was different. It was a high pressure pump, but, as I recall, it used the shorter gears. It was GM #475902, but it was discontinued quite awhile ago. This pump was also supplied with a tack-welded on pick-up screen, but it was of a totally different configuration than that used for the 3969870 pump. The pick-up screen for the 475902 pump was much smaller than the 3969870, but it was also positioned for use with the Corvette oil pan.

[Joe L.]

Re: Boring oil pump stuff

Jerry------

The GM #3969870 oil pump is the ZL-1 oil pump and it does have the 1.3" gears. This pump will work just fine in most big blocks. It comes complete with a tack-welded oil pump pick-up which is positioned to work perfectly with any stock 65-74 Corvette oil pan. It has to be re-positioned for most other oil pans, though.

The L-88 oil pump was different. It was a high pressure pump, but, as I recall, it used the shorter gears. It was GM #475902, but it was discontinued quite awhile ago. This pump was also supplied with a tack-welded on pick-up screen, but it was of a totally different configuration than that used for the 3969870 pump. The pick-up screen for the 475902 pump was much smaller than the 3969870, but it was also positioned for use with the Corvette oil pan.

[Clem Z.]

Re: Boring oil pump stuff

joe the L-88 pump and screen,475902 is still in the 2001 perf. parts book. the 3969870 pump and screen is listed as a LS-7 pump with 1.3 long gears and they list a high volume pump with 25% more volume part # 10051105

[Clem Z.]

Re: Boring oil pump stuff

joe the L-88 pump and screen,475902 is still in the 2001 perf. parts book. the 3969870 pump and screen is listed as a LS-7 pump with 1.3 long gears and they list a high volume pump with 25% more volume part # 10051105

[Clem Z.]

Re: Boring oil pump stuff

piddle valve lifters allow 20% more oil to flow to the rockers that the edge orifice lifters,but all solid lifter BB used piddle valve lifters from the factory. when i used full roller rocker arms i always use edge orifice lifters and never had a valve sticking problem. the burning up of the rocker balls/arms will happen with stockt rocker arms if you use covers without the drippers because the oil shoots clear over the pivot point. with stock rockers and covers with no drippers i welded a small tab on the rocker arm over the push rod dimple so the oil would hit the tab and not shoot clear over the pivot point.

[Clem Z.]

Re: Boring oil pump stuff

piddle valve lifters allow 20% more oil to flow to the rockers that the edge orifice lifters,but all solid lifter BB used piddle valve lifters from the factory. when i used full roller rocker arms i always use edge orifice lifters and never had a valve sticking problem. the burning up of the rocker balls/arms will happen with stockt rocker arms if you use covers without the drippers because the oil shoots clear over the pivot point. with stock rockers and covers with no drippers i welded a small tab on the rocker arm over the push rod dimple so the oil would hit the tab and not shoot clear over the pivot point.

[Joe L.]

Re: Boring oil pump stuff

clem-----

Actually, the GM #475902 is also listed in the just-out 2002 GM Performance Parts catalog. Unfortunately, the piece was discontinued in December, 2000.

The GM #3969870 pump was used in PRODUCTION for the 1969 ZL-1 and as a component of the SERVICE-only LS-7 crate engines. It is a high volume pump.

The GM #10051105 pump is actually a similar pump that is used on Gen V and GenVI big blocks, but can also be used on earlier 65-91 Mark IV big blocks. However, it is not supplied with a pick-up screen. That's perfect for folks who use non-Corvette pans since they don't have to remove the tack welding and reposition the pick-up of the 3969870 pump.

[Joe L.]

Re: Boring oil pump stuff

clem-----

Actually, the GM #475902 is also listed in the just-out 2002 GM Performance Parts catalog. Unfortunately, the piece was discontinued in December, 2000.

The GM #3969870 pump was used in PRODUCTION for the 1969 ZL-1 and as a component of the SERVICE-only LS-7 crate engines. It is a high volume pump.

The GM #10051105 pump is actually a similar pump that is used on Gen V and GenVI big blocks, but can also be used on earlier 65-91 Mark IV big blocks. However, it is not supplied with a pick-up screen. That's perfect for folks who use non-Corvette pans since they don't have to remove the tack welding and reposition the pick-up of the 3969870 pump.