Valve lash on a 427-425 - Team Camaro Tech
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post #1 of 5 (permalink) Old Mar 27th, 11, 10:56 PM Thread Starter
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ernie
 
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Valve lash on a 427-425

is the cold valve lash on a 427-425 solid lifter motor set at 30thsn on int and exh? thanks
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post #2 of 5 (permalink) Old Mar 28th, 11, 07:55 AM
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Re: Valve lash on a 427-425

It is the same as L78.

From memory it is 0.024 intake and 0.028 exhaust but let me see if I can find the L72 Sun tune up sheet. Set "hot and running". You can go a little tighter than that - say 0.022 and 0.026 to see if it likes that any better.

Setting them cold is similar to the procedure for the 30/30 cam. Set cold numbers a bit tigher if you are using stamped stock rocker arms.
http://www.camaros.org/302valves.shtml

Let's see what others say.

68 Camaro SS 396 - 468 BBC now, M21, 12 bolt 3.73 coded housing but w/ 3.31 gears.
Looking for 68 Camaro with body number NOR 181016
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Last edited by bcm66; Mar 28th, 11 at 09:28 AM.
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post #3 of 5 (permalink) Old Mar 28th, 11, 09:10 AM
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Talking Re: Valve lash on a 427-425

Quote:
Originally Posted by bcm66 View Post

If you are going to set it cold, you will need to be a little tighter, since it will loosen up when hot. ...

Let's see what others say.
I'd say that clearances get 'tighter' as an engine heats up - not 'looser'
As the metal in the valve train expands the lifter, pushrod, and valve stem elongate - taking up clearance in the system.

If setting cold, add a 'couple-thou' (@.002") to the "HOT" setting and recheck once the engine has reached operating temps.

IIRC, the lash settings given are correct - or close enough.
Some of the higher HP BB's recommended a slightly tighter Exhaust (@.026" vs. .028") but the Intakes were almost all the same at .024"

But - lets see what others say

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post #4 of 5 (permalink) Old Mar 28th, 11, 09:24 AM
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Re: Valve lash on a 427-425


It's early...

I will go back and change that wording...

Hot is best, but this is from that article I linked to above...

Quote:
...an alternate method of obtaining the required lash dimension for a given solid-lifter setup is to accurately hot-lash the valves to the cam manufacturer's specifications, allow the motor to cool, immediately re-measure the lash while cold, then use that cold lash measurement for subsequent cold lash setting.

68 Camaro SS 396 - 468 BBC now, M21, 12 bolt 3.73 coded housing but w/ 3.31 gears.
Looking for 68 Camaro with body number NOR 181016
CRG -
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Last edited by bcm66; Mar 28th, 11 at 11:19 AM.
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post #5 of 5 (permalink) Old Mar 28th, 11, 10:32 AM
DjD
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Re: Valve lash on a 427-425

Per the '69 chassis service manual, 427/425 should be .024 and .028 at operating temp. That may not apply if the cam and lifters are a retrofit grind...

...Dennis

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