What is the preload for the comp 850-16 OE replacements?

If you follow comps pushrod length "how to" (http://www.compcams.com/information/Products/Pushrods/) it mentions nothing about preload, it just says to measure using the adjustable and order that length. Is this only for solid lifters? There would be quite a big delta between ordering just what is determined using the adjustable pushrod, and ordering what is determined using the adjustable and adding to it the preload like everyone says to do.

 

I'm using Comp 850-16's and I have my cold lifter preload set to .065"-.070".

 

Do you have a lot of valve-train noise???

 

Hmmm. I have valve-train noise. Is it excessive? I don't think so. What would you recommend I set my pre-load to?

 

I was going to ask you....

 

Interesting. One would think that since this is so VITAL to the engine that this would be more of an exact science!

 

The numbers and procedure I got from a post by Tony Mamo. I know he's played around with these motors a bit so I used his recommendations. .050"-.100". I read that if I wanted it quieter, I could go closer to .100", but I've read that at high rpm's the lifter can pump up some and kill upper end performance. That's why I stayed in the middle. I'm running 7.35" pushrods, because my adjustable pr checker measured 7.28"-7.29".

 

The lifter by design is meant to have a tolerance of acceptable pre-load... I will dig for more info but I believe .050 to .100 more than zero lash is the window with most looking for something around .065

 

That's the thing about a hydraulic lifter. It's designed to work within a range to take into account variations in valvetrain geometry that occur due to heat expansion/cooling and component wear. If you are in that range, you should be fine, with those lifters.
One other thing I noticed is Comp recommends .020"-.040" of preload and they do it a different way. They say to use a standard PR and set it to 0 lash on the lobe heel. Then to scribe it. Then torque the rocker down and wait 5 minutes for it to bleed and scribe it again. Then take it out and measure the distance between the marks. It should be .030" +- .010". But this isn't for an LS1, and not for 850's.
Many on this forum will tell you anywhere between .060" and .080" cold is the correct preload.

 

I have the 850-16 lifters and my pre-load is adjusted to .075 - .100". I have valve train noise (like a sewing machine) due to the higher than stock lifts and the extra mechanical mechanism of the roller tip rockers. When I tried .030" pre load, I had significant clicking noises (like mechanical valves that were set too loose). I'm very comfortable with my current pre-load on these factory replacement style lifters. If I had the Pro Magnum Lifters, it would be too much and probably unseat the valves and not allow them to fully close. Comp's instructions are written around the Pro Magnum style lifters in my opinion.

Hope this helps!

Steve

 

I'm using comp 850-16 lifters and pro magnum rockers. This is good info! Thanks.