Different lifters

[Belgium R/T -68]

Comp cams have 2 different lifters for hydraulic cams, pump-up and anti-pump. What's the difference and which ones to use with a ,534" valvelift?

[firefighter3931]

Comp cams have 2 different lifters for hydraulic cams, pump-up and anti-pump. What's the difference and which ones to use with a ,534" valvelift?

Per, the anti-pumpup hyd lifters are designed to be used with an adjustable valvetrain with very small lifter preload. If you're planning to use a stock non adjustable rocker arm assembly go for the standard pump-up lifters. 



Ron

[Belgium R/T -68]

Am I wrong thinking that old stock system gives a lot of losses due to geometri problems giving different liftheights because the rockers
are not 100% correct? Doesn't feel good to put all the efforts and money into the strokebuild and put 40 year old rockers on it. 

[firefighter3931]

Well, you wouldn't be reusing 40 year old rockers....you need to replace them with a stronger reinforced stock style replacement piece. 

Yes you will lose some rocker ratio with the stamped steel replacement rocker but the power difference with such a mild combo will be minimal. I bet you wouldn't feel the difference in the seat of your pants. 

The factory stuff is cheaper, lighter and maintenace free. No preload to set or check. 


For a cruiser build that won't ever see more than 6000 rpm the HD replacement style rockers are fine. Mike (MFR426) has the HD replacements in his 500in stroker with the K60 cam. When he had it on Barton's Dyno there were no issues whatsoever with the valvetrain and they did pull to the valvecovers to make sure. 



Ron