Very quick question about setting zero lash on valves
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,193
Likes: 176
From: Hillsborough NC
Very quick question about setting zero lash on valves
OK, last night we got the new cam in and went through the degreeing procedure. That all went fine and was a great learning experience.
Afterw, I was test fitting the pushrods to check for rocker alignment and have a question on zero lash.
We rotated the crank until we were positive that the lifters for the cylinder were on the flat spots of both lobes of the cam and then began to tighten the nuts until I felt no up or down, but a slight drag on twisting. Here's the question:
When you are correctly set at zero lash with hydraulic lifters, should spinning the push rod also start to spin the lifter in the bore? Obviously they shouldn't rotate at the same speed, that would be too much pressure, but should they spin at all with the pushrods?
Thanks
-Fred
Afterw, I was test fitting the pushrods to check for rocker alignment and have a question on zero lash.
We rotated the crank until we were positive that the lifters for the cylinder were on the flat spots of both lobes of the cam and then began to tighten the nuts until I felt no up or down, but a slight drag on twisting. Here's the question:
When you are correctly set at zero lash with hydraulic lifters, should spinning the push rod also start to spin the lifter in the bore? Obviously they shouldn't rotate at the same speed, that would be too much pressure, but should they spin at all with the pushrods?
Thanks
-Fred
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
There is a spring inside the lifter that will compress as you tighten down the rocker. Don't worry about the lifter spinning or anything like that. Once you have taken all of the play out of the valve train all you are moving after that is the spring in the lifter (and that is what gives you pre-load). Zero lash is when you have no more free movement (up and down) and you feel the spring tension that makes the pushrod a little more difficult to rotate. It isn't a huge difference in feel but it is noticeable.
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
To eliminate almost all "subjective" twisty bouncy differences when setting lash, just snug up a .002 feeler gage between rocker & valve tip to find zero lash. Gets it a heck of alot closer to actual zero lash on a consistant basis than twisty bouncy....
Eddie
Eddie
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,193
Likes: 176
From: Hillsborough NC
That's a great idea. Thanks!
