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.
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.
Comment