Is zero lash when I cannot spin the pushrod at all, or when there is any drag on the pushrod?

Once I know that, I have heard R's like 1/16 past zero lash. Is it normal to be able to push the rocker a lil both ways (not off the valve, but a lil movement) when the valve is closed? I am running Comp Pro Mags, GM guide plates, hardend pushrods and Comp R's.

Let me know!

James

PS. Happy Thanksgiving!

 

It's when you feel drag. 1/16th is about right. Some leave it at zero lash, but I would personally recommend finishing the work with the engine running.

 

Zero lash is when there is no slack between the pushrod and the rocker. I havent ever used the "spin the pushrod" method because I feel it's very inaccurate and misrepresents zero lash in some cases. If you can feel drag, your past zero lash. I prefer to pull up on the rocker arm, and adjust the nut until there is zero slack. This is zero lash.

 

I usually don't know what I am talking about, but it seems that if you don't use the drag method when looking for 0 lash that you might be depressing the the lifter and then when you use 1/16 additional adjustment that you might be too tight. Although pre setting is not a precise procedure, seems that if you don't provide any margin for error that you may jeopardize the integrity of the valve train. JMHO

 

You shouldn't be able to compress a lifter that easily though. The up/down method is probably the most precise because you're positively identifying the point where there is no more room for vertical movement from the pushrod, I.E. zero lash. Spinning the pushrod will not as accurately tell you when it's at the zero lash point. If you're feeling drag on the pushrod while trying to spin it, then you're already past zero lash. This may not be such a big deal on a stock lifter, but if you're using a Comp "R" and 7/16" stud, it could be the difference in how your motor runs.

 

I think that either the "spin" or the "up/down" methods will work fine. I never understood the fascination with adjusting lifters with the eninge running. I have been fooling with cars for ~40y and never did it that way. Hey, but if you like getting splashed with hot oil, why not?

rich

 

I am going to agree with the majority here. We just got done doing a cc306 cam install on my little brother's 95 Formula. We also used the Comp R lifters and 7/16 rocker studs.
The absolute easiest way with this setup is the up and down method. I have NEVER set zero lash on ANY motor in my entire life. When I did my little brother's car, it was the absolute first. I used the up/down and as soon as there was no more travel up/down for the rocker arm, that was determined to be zero lash. We went like a 32nd, possibly a 16th, past zero lash, but hardly anything. 400 miles later and absolutely no problem (knocks on wood )
Good luck, and if you need any help, I am right here local in Frisco Texas. I could swing by and give a fellow board member a hand if you need it.