ZL-1 valve adjustment
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Le Mans Master
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From: Richmond Kentucky
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ZL-1 valve adjustment
When performing a "cold" valve adjustment on a ZL-1 engine with mechanical roller camshaft, should the clearance be set a few thousandths looser than recommended in order to allow for metal expansion at operating temp?
Racer
Joined: Feb 2009
Posts: 273
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From: Algona, WA
I set mine .006 tighter when cold, .014IN/.016EX Once the motor is up to temp and heat saturated, I recheck and they end up at .020IN/.022EX... On a aluminum Head/Block set them tight. Some engine builders say as much as .012 tighter.... but mine will grow .006 once heated up.
Dave,
Dave,
Last edited by d555; Oct 10, 2010 at 01:58 AM.
Advanced
Joined: Jun 2010
Posts: 86
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From: Pulaski Wisconsin
Dave, are you sure about that? If you set them cold, yes they do grow when they get warm and or hot which would mean this measurement will get tighter. I think you have you numbers turned around.
Burning Brakes
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Racer
Joined: Feb 2009
Posts: 273
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From: Algona, WA
On an all aluminum motor the head/block will grow way more than the lifter push rod. You set tight when cold. Re-check when HOT. 
Lots of expansion with these motors. set up is lot different than Iron.
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Le Mans Master
Joined: Oct 2007
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From: Richmond Kentucky
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Thanks guys.......................looks like I had it reversed !!
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I'm running a hydraulic cam in mine, and I was amazed at the growth the first time I got it warmed up good. I had the same preload that I ran in the old iron block/aluminum head engine, but ended up having to add a bit more to quiet things down.
