Is it true adjusting the lash very lightly will help with rev's with a heavy rocker arm that I have the comp pro mag? I was told by one of my builders to adjust the lash very light like 1/8 of a turn from zero does this sound right? Thanks. Comp's specs for adjustment are like 3/4 of a turn from zero? Thanks

 

I am not sure which engine you are working with? Is this a GenIII / IV engine or a Gen I/II. With the Gen III/IV engine you have no choice but to preload them to spec of 22lbs (unless your using some after market setup).

With the tradional SBC, you can adjust the pre-load from anywhere from zero to 1 1/2" turns depending on which lifter you are using. Changing the preload can either give you more low end TQ or Upper end HP.

Most SBC rocker studs are 3/8-24".. so one turn will only move the reload into the lifter by 1/24". You are playing with a very narrow range of adjustment.

 

This is an ls1 with comp pro mag rockers. Comp cams says to adjust 3/4 of a turn from zero lash and I got a tip from one of my engine builders to go very light on the lash like only 1/8th of a turn to help with the revs.

 

This has never really been proven on LS motors. The lifters are hydraulic, so by lowering preload, what you do is making the lifter work harder and there could be a possibility of valve instability due to the lifter not being able to pump up quick enough at high rpm. IMO just use the right preload.
If in stock lifters .060>.070 cold (.080 /.090 hot)

 

With stock lifters, Vinci has actually found the opposite, i.e., he found more lifter preload provided a better curve. You might want to contact him and get more input on his findings. I think they also have something about this on their web site.

Also, running low lifter preload on an aluminum LS1 could result in no preload at temperature, which isn't good for the snap retainers in the top of the lifter.