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Roller cam differences


Guest zfan

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A friend of mine purchased a Doug Herbert roller cam awhile back and began running hydraulic roller lifters with it but then decided to run solid/mechanical roller lifters with it.

 

He sdaid it didn't make a difference at all and that Doug Herbert's catalog doesn't even mention what ones to run other than it is a roller cam. He said I should run solid roller lifters with my cam instead of hydraulic rollers. He said just change out the springs.

 

I called Comp cams who is my cams manufacturer, They stated yes I could run solids but to run a tight valve lash. Set them at 8-9 hot and watch that they stay tight on the lash.

 

Does anyone know why you shouldn't run solid roller lifters on a hydraulic roller cam? Comp said only that ramp speeds are different but never gave me a solid answer. I also called crane and Crower and they said you could just be careful with the lash. Only one Crane rep said he wouldn't recommend it.

 

I just would like to know why the difference and pro's/ cons. That said I think I am going to go with the Crower 00426 solid roller cam in my 385 sbc with 11 to 1 compression.

 

Like I said I am just curious but will not do this as I do not want to risk my motor.

 

Mike

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The lobe on a solid lifter cam has a slower ramp right at the beginning to take up the lash gently before the ramp really takes off. Since a hyd lifter has the preload and the hydraulic "cushion" to absorb the shock, the hyd lifter doesn't need the slow ramp right at the beginning. You can mix and match as long as you're aware of what's going on and how to deal with it. You need to keep a close check on the lash, if it gets excessive the impact forces will accelerate valvetrain wear very quickly.

 

John

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The lobe on a solid lifter cam has a slower ramp right at the beginning to take up the lash gently before the ramp really takes off. Since a hyd lifter has the preload and the hydraulic "cushion" to absorb the shock' date=' the hyd lifter doesn't need the slow ramp right at the beginning. You can mix and match as long as you're aware of what's going on and how to deal with it. You need to keep a close check on the lash, if it gets excessive the impact forces will accelerate valvetrain wear very quickly.

 

John[/quote']

 

You're running a risk of premature failure, but if you don't overrev and keep the lash tight, there shouldn't be a problem unless you are running a very extreme cam where they tried to maximize the ramps.

 

Hydraulic lifters sacrifice a little hp at low rpm but have a generally calmer idle and better gas mileage at low crusing speeds (the cam is not fully utilized acting like a choke plate which will increase mileage through milder effective cam performance.)

 

That said, everything I said is subjective, you still run the risk unless you research the cam you have and assure yourself it's not more agressive than is recommended by historical evidence.

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