CamaroSS30thAnn

Im running a 234/244 598/614 cam
comp 850 lifters
comp 1.6rr
7/16 rocker studs

Cars up and running but have a question in preload for the comp 850 lifters. I seem to get an awful lot of noise.

What would be a good preload? Right now ik at 1/4 after 0 lash.
comp recommends half to 3/4 from what ive read but there is a lot of conflict on this.
Just looking for opinion and anyone who runs similar set ups.

Chimera96

FWIW I started with a 1/4 turn with my 850's on my 383 H/C build. To me they were a little noisy. Went to 1/2 turn and they were better and then I went between 1/2 & 3/4 turn and am happy with the results. Motor now has about 40k mi on it since the lash at that setting

Of course starting from what I feel is zero lash and what you or others may will be different. I use the "no more up/down movement" for zero vs the "spin until you feel a slight drag" method of finding zero lash. IMHO the later method you blew by zero at least a 1/4 turn ago if not more.

my cam is smaller lift than yours .570/.565

CamaroSS30thAnn

So your saying its better to do the up down movement?

CamaroSS30thAnn

The only thing im afraid of is having them to tight and causing issue.

Chimera96

Well IMHO I use up/down method. When there is no more movement of PR "up/down" as I finger tight the poly (read very gently finger tight) than that is "zero" lash and from there you go with whatever "pre-load" you want. GM service book says 1 to 1 1/2 turns. Some feel with high lift cams and high (above 5700) rpm shifts than a lower pre-load (1/4 to 3/4 turn) is better

For me I found just a little over 1/2 turn (about 3/4) works well for me. 1/4 turn was OK in terms of performance but was just a little noisy, especially after car had warmed up so I went 1/2 then decided just a little more work best for me in terms of noise and high RPM use is solid

Lifters, just like any other part in a motor, is a wear item especially with high lift cams and high RPM use so they can "fatigue" and if they get noisy even after repeated lash than changing them would be required. Stock lifters in a untouched stock motor kept in good operating condition can last, and should, the lifetime of the motor.

CamaroSS30thAnn

Thank you. Yes i understand.
A quarter turn is just annoyingly loud especially when running hot. So i think i may do a half turn and se how i like it.
ill use the up down method.
Basically make sure the pistons at TDC. Tighten the rocker until up/down no longer occurs then preload half a turn and lock.
ill do it warm also.

STSturboLT1

I went a full turn with my setup and have no complaints about valvetrain noise.

CamaroSS30thAnn

I think im gonna try half turn for now. And go from there.
ive got the composite valvecovers now so i assume that os gonna lessen the noise.

Chimera96

The composite covers that were on the LT4 were to help reduce the noise of the RR. LT4 knock "module" was also less sensitive to the sound of RR

CamaroSS30thAnn

yessir they are lt4, no longer have an lt4 km, im 24x