zero lash
03-13-2013, 09:13 AM
#1
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zero lash How do you know when your at zero lash? Will the pushrod move at all? Should you be able to move the pushrod with the rocker at 22 lbs or should it be tight.I know there can't be any load on the lifter but how do you determine when your at zero lash?
03-13-2013, 09:34 AM
#2
what exactly are you doing - are you measuring PTV? if so then you should be using solid lifters when doing this. but the rocker won't be fully tight at zero lash if your push rods are the right length - it'll be snug to the point that there is no play between the rocker and pushrod. tightening it down the hole way will either preload your lifter or hang your valve open further than normal and skew your measurement.
03-13-2013, 10:27 AM
#3
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They are morel link bar street hydrolic lifters and ultragold comp rockers. Should the push rod be just snug under the 22 lbs of torque or tight. Trying to determine were zero lash is and measure PR length
03-13-2013, 10:35 AM
#4
Refer to this:
dont worry bout the other posts, I think thats the main one you may want to look at
I couldn't agree more...forget the bolt turn method. You'll have to remove the checker and adjust the length a few times (go in half turn increments) until you find the sweet spot where there is no more slack between the lifter and the rocker, that will be your zero lash. Then add your .050" of preload (we run about .030") to the length of your checker and that will be the length of the pushrod you will want.
Last edited by Tainted; 03-13-2013 at 11:37 AM.
03-13-2013, 11:34 AM
#5
Zero lash is found with the lifter agaisnt the base circle of the cam and the rocker tight in place. I usually lift the rocker tip until the clearance just disappears and keep lengthening the adjustable pushrod until the "tick" "tick" just disappears. Old school was to rotate the pushrod but I never found that to work for me.
If the lifters are new and not filled with oil, be very gentle with the measurements because it is very easy to depress the plunger into the lifter adn not realize it. I ran into this with the first measurements I made with my Morel lifters.
If the lifters are new and not filled with oil, be very gentle with the measurements because it is very easy to depress the plunger into the lifter adn not realize it. I ran into this with the first measurements I made with my Morel lifters.
03-13-2013, 11:36 AM
#7
yea I noticed that after you posted. im looknig for the other one that ryan had explained now.
** ***oh and vettenuts if you would check the post and see if my example was correct or not if you would.
**
I couldn't agree more...forget the bolt turn method. You'll have to remove the checker and adjust the length a few times (go in half turn increments) until you find the sweet spot where there is no more slack between the lifter and the rocker, that will be your zero lash. Then add your .050" of preload (we run about .030") to the length of your checker and that will be the length of the pushrod you will want.
Last edited by Tainted; 03-13-2013 at 11:42 AM.
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03-13-2013, 11:45 AM
#9
The pushrod will not be loose is the best way to explain it. I think "snug" may be too tight but at that point we are into semantics. If too long with new lifters, you may start depressing the lifter plunger. Not sure what you are shooting for with regards to preload, but the Morels have a fairly narrow range.
03-13-2013, 04:04 PM
#11
I found with the new Morels (not run yet) I could easily depress the plunger with my hand and with the rocker. So you need to be very careful with the measurements.
Take your measurement at zero lash. To double check, rotate the pushrod some to loosen it up so the rocker tip will "tick" when lifted. Then gently lift the rocker tip until it just touches the pushrod. Now use a feeler gauge to measure between the valve stem and the rocker tip. Divide that measurement by 1.54 and add it to your pushrod length to get zero lash. If the two measurements are close then you are at zero lash.
When to rotate down the pushrod, pick a length that is at an exact turn. In other words, lets say you are getting 9.5 turns to zero lash, then turn it down 1/2 turn so the adjustable is at 9 turns then double check with the feeler gauge.
The two answers won't likely be exactly the same but should be close.
Hope this makes sense.
Take your measurement at zero lash. To double check, rotate the pushrod some to loosen it up so the rocker tip will "tick" when lifted. Then gently lift the rocker tip until it just touches the pushrod. Now use a feeler gauge to measure between the valve stem and the rocker tip. Divide that measurement by 1.54 and add it to your pushrod length to get zero lash. If the two measurements are close then you are at zero lash.
When to rotate down the pushrod, pick a length that is at an exact turn. In other words, lets say you are getting 9.5 turns to zero lash, then turn it down 1/2 turn so the adjustable is at 9 turns then double check with the feeler gauge.
The two answers won't likely be exactly the same but should be close.
Hope this makes sense.
03-14-2013, 06:37 AM
#12
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Some of the plungers depress and some are hard to move, I checked 5 cylinders and the first one I was able to depress plunger at zero lash with 10 turns=7.340PR length with .040 preload so I was going to go with 7.350 PR. Is it normal to not be able to depress all plungers because the lifter is tight? The one I was not able to depress had some movement at rocker tip. Also has anybody had any clearance issues with ultra gold rockers and stock valve covers, can has a 580/590 lift
03-14-2013, 06:54 AM
#14
Cam? Different cams have different base circles. You really just need to measure with a push rod length checker. Comp sells one on jegs for $12. With the rocker at 22fl/lbs the length checker should just barely take up the slack in the rocker, lifter and PR. No more or less. Take the checker out. Measure with a caliper. What ever it reads add your preload to it and there's your PR length. Check int and exh separately because they may be different.
