Valve lash ?

[otto]

Hi , just removed valve covers on my new to me cobra to check out what i had for a rocker setup, former owner wasn't sure on the spec's on the camshaft but i have .032 of lash which seems like a lot. any advise on adjusting without removing the camshaft to ID. Motor is a 66 S/O mid rise
thanks Bob

[Jac Mac]

All of the OE mechanical cams ran 0.025" lash according to a 'Muscle Parts Catalog I still have. I also checked my Comp Cams catalog & with the exception of two fairly radical drag cams they recommend 0.022" lash for their mech grinds, so I think you would be fairly safe to set the lash @ around 0.020/0.025", but if you can find out from the actual builder of the engine in question he might be able to help pin down the actual camshaft used.

[blykins]

Make sure you distinguish between cold lash and hot lash. Especially with aluminum heads, lash gets bigger. So for instance with an iron block aluminum head engine, if you started out with .020" cold lash, it could grow to .026-.028" hot lash.

That could be another reason why there is so much in your particular engine.

[otto]

Hi , sorry i should have given more info , it has factory cast iron mid rise heads so i would think the lash wouldn't grow as much , J Mac would those figures be hot or cold
thanks again for the info Bob

[blykins]

Lash is always given as a hot spec, unless otherwise specified.

You're correct, it won't grow very much at all with iron heads.

[Jac Mac]

As per Brents recommendation, always when hot unless specifications say otherwise..

[byron w]

Hi Brent,

Again, if iron heads, block and factory OEM cam, it is .028 cold and .025 hot which is as Brent so correctly state's just backwards from aluminum heads and iron block.

Byron

[Barry_R]

You guys are overthinking this.

Just start off with .020 cold and see if you like it. When measured at the cam a .004 difference in lash is just a hair over two thou - nowhere near enough to ever hurt anything at all. Try it and adjust to your personal tastes...just make certain you have "some".

[blykins]

I don't see where there was any overthinking...

There were a few posts about where to start and then there were a few posts about which way the lash grows and when you measure it (hot/cold).

To the OP:

On what Byron is saying, just be sure to check it both hot and cold to get a good idea of what it does when the engine is good and hot.

[SKIP Q]

Hello otto
There is some good info in a post originally posted by Argess 9-24-2009.
Valve Lash Hope this helps.

SKIP

[55312]

As Byron said - .028 cold and .025 hot. That's right from my 1965 Ford Shop manual.

Tim

[blykins]

Those specs are for:

1. Production camshafts

2. Production engines

Aftermarket cams can have different lash specs and as Barry noted, you can vary those specs to get the engine to behave the way you want.

With the introduction of aftermarket valvetrain, aftermarket rocker arm assemblies, etc., never assume that lash on an iron block/iron head combination will shrink. Always check both cold and hot lash and don't be surprised when it doesn't behave per the older Ford shop manuals.