If you were my customer and I built the engine it would have factory lifters--GM-- General Motors...or a factory replacement lifter.

Isn't that what the posters are trying to tell you,that factory lifters would be fine??????

 

Comp 612's and CC306, not really stock. Not sure on the comp 850's don't run anything but their cam and rocker arms on my car.

 

First off... people have so much trouble with comp-r lifters because they dont know how to lash them. They require very tight tolerances and too tight or too loose can cause failure.

The stock lifters are fine for smaller cams, but using RPM and pressure to judge how much they can handle is BS. The pressure on a lifter comes from 2 sources. One part comes from spring pressure multiplied by the rocker ratio (alot of LS1 guys overlook this, when they should be more careful due to the 1.7+ ratios of their rockers). The other part is caused by acceleration of mass. F=MA. When you accelerate a lifter at a faster rate (faster ramp rates) it causes more force. Also when you increase RPM, it causes it to accelerate faster as well creating more force. What people also forget to mention is valve train weight. The M in the F=MA equation is MASS. If you have a heavier valvetrain, it causes more force on the lifter.

So there are more variables involved in calculating force on a lifter than just RPM and spring pressure.

I would say that if you are running serious ramps with a good ammount of spring pressure on a street car, go with the comp-rs. Its worth the peace of mind and lash them with the motor warmed up and running. Either that way or with a feeler guage. Spinning the pushrod is about as accurate as trying to **** in a bucket drunk and blindfolded.

 

Spinning the pushrod is about as accurate as trying to **** in a bucket drunk and blindfolded.[/QUOTE]

If you don't know how it is.

 

Yea, I never liked that method. I could NEVER seem to get it even close enough to keep comp-rs happy. It worked for stockers, but comp-rs needed a feeler guage or the engine running to hit the lash right.

 

Ehh they work just fine for me. I lashed them 1/8 past zero lash however accurate that can be... I found that lashing them with the car on proved to be more difficult than it seemed because you have to lock them down or the nut will back itself off if you go on to the next rocker. One of these days I'll get around to doing them again with the car running, simply for peace of mind...

 

how do you use the feeler guage method? is it the same one you use for like gapping spark plugs?

 

also where can you buy the sealed power lifters?

 

good question... looks like I might not be using comp r's

 

O'reilly's sells Sealed power lifters for lt1's. Comes out to $198 w/ tax. Helps if you have a buddy who can give you his discount.

 

any advanced auto parts store should have them if not they can get them. its just a normal s/b chevy lifter made by sealed power

 

Dam good post man...... I mean that seriously.

I'm working on a design on a motor right now and I'm fighting going with a 2:1 rocker and a low lift lobe vs. a 1.8:1 rocker and a high lift lobe, due mostly to the forces applied to the lifter and pushrod.

It's not on a Comp R BTW

I'm a big fan of Comp R's, i've seen them take tons of pressure and abuse as well as lobes that have no right being run by a hyd lifter. The whole supplier BS that they had a few years ago is still not fixed. I've seen plundger retainers fail due most likely to a improper heat treat, which doesn't suprise me because a good heat treater is hard to find that's why most race parts makers do theirs in house.

Bret

 

well the way i adjusted them was to move the pushrod up and down until there was no slack between the pushrod and the rocker arm, and left it at that. is that ok to do? also i called today and they said to send them back and they will send new ones out.