ZL1 Cam Cold Lash

bbbentley · #1 07-09-2020, 09:45 PM

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.

**L_e_e** · #2 07-09-2020, 10:43 PM

Quote:

Originally Posted by bbbentley

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"

**jerry455** · #3 07-09-2020, 11:34 PM

What if engine has factory aluminum heads? Still add .002?

**lbnaz** · #4 07-10-2020, 12:06 AM

I set mine as per specs w/alum heads and had no issue. Larry

**RobR** · #5 07-10-2020, 12:22 AM

Quote:

Originally Posted by bbbentley

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?

bbbentley · #6 07-10-2020, 12:24 AM

Quote:

Originally Posted by RobR

Head material?

Block material?

Iron&iron. Basic L72 w zl1cam

rszmjt · #7 07-10-2020, 12:31 AM

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.

**RobR** · #8 07-10-2020, 12:46 AM

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.‬

KenMaisano · #9 07-10-2020, 03:03 AM

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.

bbbentley · #10 07-10-2020, 08:56 AM

Quote:

Originally Posted by RobR

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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