valve lash - Team Camaro Tech
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post #1 of 7 (permalink) Old Apr 10th, 02, 07:17 PM Thread Starter
 
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Ihave a 1977 Z28 4speed with 350 motor I just put on a new set of heads and would lik to know the proper valve lash
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post #2 of 7 (permalink) Old Apr 10th, 02, 09:09 PM
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Check with your cam mfg. They will know.

------------------
69 Camaro Z28 "clone" - 327 AT
"461" camel back heads,
edelbrock, hooker, ultradyne,
TRW etc.
700R4 TPI transmission
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post #3 of 7 (permalink) Old Apr 11th, 02, 02:49 AM
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Normal GM hydraulic lifters (not roller or mechanical (solids)), its one turn down from lash. Not centering the lifter plunger by proper adjustment can result in improper lubrication and valve operation.

Lash is when push rod does not readily move in relation to the rocker arm.


[This message has been edited by elcamino (edited 04-11-2002).]
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post #4 of 7 (permalink) Old Apr 11th, 02, 05:49 AM
DjD
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Lash is the clearence between the lifter, pushrod and rocker. Solid lifter cams require the use of a feeler guage to adjust and different grinds require different lash. Check with the manufacture.

Hyd cams are all set to zero lash, (no free play) between the lifter, pushrod and rocker. Then require a bit of preload. Usually preload is anywhere from 1/4 turn to 3/4 turn tighter. Again check with the manufacture.



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post #5 of 7 (permalink) Old Apr 11th, 02, 05:27 PM Thread Starter
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by HOTRODMAN76:
Ihave a 1977 Z28 4speed with 350 motor I just put on a new set of heads and would lik to know the proper valve lash<HR></BLOCKQUOTE>

This motor has factory style hyd lifters The
info on lash adjusments will help thank you
for the info hotrodman76
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post #6 of 7 (permalink) Old Apr 12th, 02, 02:28 AM
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Mike
 
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Here's a quote from a 70's Chevy service manual.


<BLOCKQUOTE>quote:</font><HR>Valve adjustment is made by backing off the adjusting nut (rocker arm stud nut) until there is play in the push rod and then tighten nut to just remove all push rod to rocker arm clearance. This may be determined by rotating push rod with fingers as nut is tightened (fig. 3V). When push rod does not readily move in relation to the rocker arm, the clearance has been eliminated. The adjusting nut should then be tightened an additional 1 turn to place the hydraulic lifter plunger in the center of its travel. No other adjustment is required.<HR></BLOCKQUOTE>


You can see from this that adjusting the lifter is not to remove noise etc but to center the lifter plunger for proper operation. If it requires 1 turn and you go 1/2 or 3/4 turn, then the lifters are not properly adjusted.

If I were you I would get a service manual before I took anything a gospel. What I quoted if from a 1970 Chevrolet service manual, I doubt much would have changed in 7 yrs as I use this same procedure in late 70's truck engines I upgraded the cams in.

[This message has been edited by elcamino (edited 04-12-2002).]
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post #7 of 7 (permalink) Old Apr 12th, 02, 03:24 AM
DjD
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I was not saying you were wrong elcamino. Not to many people are going out and putting GM ground cams and lifters in their engines theses days unless it's a crate and even if they do less than a full turn isn't going to cause problems. If you go a full turn on an aftermarket cam and lifters it may be too much so I tend to lean to the safe side when it comes to advice.

Read what comp says... http://compcams.com/catalog/020.html and note I did say check with manufacture...

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