mjackson92rs

iTrader: (1)

Hey guys, question on the numbers from the cam doctor report below. What I don't understand is the intake/exhaust lift numbers. My comp card says 224/242 at .634/.615. The cam doctor has the same durations but a .623/.603 for intake/exhaust lift. However, if you multiply the "peak cam lift" value by the rocker ratio 1.7, I get the values on the comp card.

What am i missing? Is the cam doctor accounting for some sort of lift loss through the valvetrain?

G Atsma

Subtract the .01 lash on the report from the cam card lift and you will be close to the numbers on the report.

mjackson92rs

iTrader: (1)

thanks! So what does 0.01 lash mean? From what I understand there is no valve lash because the lifters have preload? Sorry still not seeing the full picture.

G Atsma

I was just looking at the report. I think all hydraulic lifters have a little give in them while running. That might be what the lash is.

00pooterSS

iTrader: (40)

That's the lift if you had .01 lash

At 0 lash the measurements check out. Essentially it means nothing except that if you had .01 lash that would be the numbers.

Cliff notes, it adds up and all is good.

As for why it's there, I don't know maybe someone here does. I could take guesses that it may be there for lifter and or push rod deflection to give you a more realistic operating lift. Or it may be there for those running solids with adjustable rockers, or that they just use .01 as a standard for measurement to make things more equal for some sort of reason. But again, at 0 lash the measurements all add up.

If you want to know the exact answer the fastest, you're best route is just call comp (or whoever did the report) and ask them. After you do, let us know, I'm curious.

mjackson92rs

iTrader: (1)

thanks to both of you! makes sense now.