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Discussion Starter · #1 ·
Unfortunately, I don't have cam specs, as I bought my car turnkey and the seller didn't have the cam card.

I'm just curious what a "typical" range should be for valve lash on a big block Chevy. (Iron block, aluminum heads).

I checked, and the lash was .036 COLD, which according to my math is about .042 hot.

That seems loose no matter what to me.

I'm wondering how tight I could/should go until I have a chance to pull the cam and have it measured.

Is .021 cold a safe number? (.027 hot)

Thanks for the help all.
 

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Discussion Starter · #3 ·
unfortunately,you will need the cam specs
I understand that. Unfortunately, for the next 60 days I won't have them.

So what's a typical range.

Tightest to loosest. What are typical valve lash specs for a BBC?
 

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My solid roller was .026 intake & .028 exhaust hot.
My solid flat tappet in my other car was .020 intake & .022 exhaust hot.

These are guide lines should be close.

Dave
 

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Discussion Starter · #6 ·
I found Reher-Morrison's cam specs online. That's what the original builder claimed the engine was. I'm not convinced the engine was a true R-M, but I think the builder at least copied R-M, and probably bought R-M components. Anyway, R-M specs say .025 for both.

I set mine to .021 cold, which is about .027 hot.

At least that's closer than the .036 cold they were set to.
 

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When I help guys that don't have or lost specs, I just go with 25-25. Haven't hurt anything yet. Hot of course.

.
 

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Discussion Starter · #9 ·
.

When I help guys that don't have or lost specs, I just go with 25-25. Haven't hurt anything yet. Hot of course.

.
Good. Thanks!

I was guessing that would be about right. I did my best to set it at .021 cold (.020 go, .022 no go). Iron block, aluminum heads.

So that should be about .027 hot. I figured that would be safe.

Unless the prior owner was intentionally trying to keep the power band low, I don't know what was going on.

The valves were around .036 - .042 cold. We'll see what difference, if any, at next week's test & tune.

Thanks again everyone. I feel more confident I made the right adjustment.
 
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