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Old 07-09-2020, 09:45 PM
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Default ZL1 Cam Cold Lash

From what I could find, the 9181 ZL1 has a hot lash of I=.024, E=.026 ? Anyone care to give a cold lash setting? I’m guessing subtract .002 off the above specs? Any help appreciated. Thanks sYc.
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Old 07-09-2020, 10:43 PM
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From what I could find, the 9181 ZL1 has a hot lash of I=.024, E=.026 ? Anyone care to give a cold lash setting? I’m guessing subtract .002 off the above specs? Any help appreciated. Thanks sYc.
With iron heads you want to ADD 0.002"
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Old 07-09-2020, 11:34 PM
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What if engine has factory aluminum heads? Still add .002?
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Old 07-10-2020, 12:06 AM
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I set mine as per specs w/alum heads and had no issue. Larry
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Old 07-10-2020, 12:22 AM
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From what I could find, the 9181 ZL1 has a hot lash of I=.024, E=.026 ? Anyone care to give a cold lash setting? I’m guessing subtract .002 off the above specs? Any help appreciated. Thanks sYc.
Head material?

Block material?
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Old 07-10-2020, 12:24 AM
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Head material?

Block material?
Iron&iron. Basic L72 w zl1cam
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Old 07-10-2020, 12:31 AM
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Iron heads & block add .002. With aluminum heads set cold lash tighter about .005-.006 on a rat motor. If it’s aluminum block & heads about .010 tighter cold. The thermal expansion of aluminum causes the lash to increase hot.
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Old 07-10-2020, 12:46 AM
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Like you said, I would go .002” LESS than the hot lash spec. ‪for break-in.‬ Then
‪with the engine at running temp, shut it off, and set the valves on one cylinder to the Hot lash on the cam card.‬
‪Let the engine fully cool down. ‬
‪Measure the lash on that cylinder that you set hot.‬
‪That will be the cold lash setting to use on all the cylinders.‬
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Old 07-10-2020, 03:03 AM
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If it is a aluminum block and heads set .012 tighter when cold. .012 .014 You will be very close to your .024 .026 when hot.
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Old 07-10-2020, 08:56 AM
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Quote:
Originally Posted by RobR View Post
Like you said, I would go .002” LESS than the hot lash spec. ‪for break-in.‬ Then
‪with the engine at running temp, shut it off, and set the valves on one cylinder to the Hot lash on the cam card.‬
‪Let the engine fully cool down. ‬
‪Measure the lash on that cylinder that you set hot.‬
‪That will be the cold lash setting to use on all the cylinders.‬
Trusting my own experience, and your reassurance, I set them .002 tighter or I.022-E.024. Great idea on the reverse calculating lash method.
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69 Dick Harrell tribute Day II 427 M20 4.10 X11 76 orig pnt, 711
67 Super Stock 302 Camaro re-creation
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