vintage chromoly

iTrader: (3)

Are you running a high rpm/high lift cam with heavy spring pressure?

For what it's worth, when we took apart my sterling built 509, it had a 55mm cam with bronze bushed lifter bores but, it had standard BBC .842 lifters. .720 lift solid roller with pretty heavy spring pressure. Maybe a class rule for the supercat program dictated the use of the .842 bore?

I asked the machinist about reaming and honing the bushings for a .903 lifter. I was told that at the relatively mild spring pressure I'll be using with my much milder cam would not justify the move up to the.903.

Black Baja

iTrader: (2)

Spring pressure no spring pressure jumping up to a larger diameter lifter gives you a bigger wheel and axle. The larger wheel is basically like having a gear reduction for the lifter. Along with a larger diameter wheel it's also wider, the wider wheel keeps the lifter from side loading in the bore this can be an issue with the smaller .842 lifters (they can gull and stick in the bore). Not so much with the .904 .937 stuff. I think it is well worth stepping up the diameter.

Black Baja

iTrader: (2)

Stiffness for sure. Do you have any idea how much a cam twist from front to back once the valves are lashed? The other advantage of the larger cam core is you can have a much more gentle lobe profile. The larger the circle the more progressive the ramp can be your an engineer so you should be able to understand pretty easily...

vintage chromoly

iTrader: (3)

I'm aware of the large wheel and axle and the advantages.

Just thought it was interesting that an engine that was engineered to run at 7800 rpm for extended periods of time with a radical cam and lots of spring pressure ( greater pressure would increase the potential for side loading said lifter) only used a .842 lifter. This engine was built by sterling and maintained by baker and ilmor.

When we pulled the lifters out there was no evidence of galling.

Cole2534

iTrader: (1)

Hadn't thought about the profile improvements from the larger base. And ya, increasing diameter is certainly good for stiffness.

Black Baja

iTrader: (2)

I have a feeling they are limited to diameter on the lifters. I know the are on cam lift and why in the world would you stick a 55mm cam in a motor and stay with the small lifter unless you were limited by rules.

mike tkach

iTrader: (3)

black baja,are you going to do this on your boat engine that will not see 6000 rpm?

vintage chromoly

iTrader: (3)

That's what I was thinking. Maybe limited by class rules?

Black Baja

iTrader: (2)

Yeah, we are going to spin 6500rpm with .800 lift cam

mike tkach

iTrader: (3)

why run .800 lift on a cam in a pleasure boat,im not being a dik,i just am not sure why.