Valve lash?-unknown cam
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Valve lash?-unknown cam

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    Senior Member Ronboats's Avatar
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    Default Valve lash?-unknown cam

    I want to adjust my rockers on my 468 BBC, but I don't know what the cam specs are, or even what manufacturer. It is a solid flat tappet cam, roller rockers. thats all I know. It has a small lope at idle-I was told it was a "mild" cam. I guess I could check the lift with a dial indicater, if that makes any difference. What is a safe setting for the valve lash? How about a cold lash setting to get them in the ballpark before I set them hot? Right now they seem to be at about 22 cold, which seems like a lot to me. The heads are iron 049s. Any opinions?

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    Senior Member Factory1's Avatar
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    All iron isn't going to grow nearly as much as aluminum, so the numbers should be close hot vs cold. .024 intake/ .026 exhaust are really common hot numbers, I wouldn't go much under that. Im just guessing here but I would think all iron would expand .004 to .006, I wouldn't cold lash it under .018 myself intake or exhaust.

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    steelcomp was here
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    Quote Originally Posted by Ronboats View Post
    I want to adjust my rockers on my 468 BBC, but I don't know what the cam specs are, or even what manufacturer. It is a solid flat tappet cam, roller rockers. thats all I know. It has a small lope at idle-I was told it was a "mild" cam. I guess I could check the lift with a dial indicater, if that makes any difference. What is a safe setting for the valve lash? How about a cold lash setting to get them in the ballpark before I set them hot? Right now they seem to be at about 22 cold, which seems like a lot to me. The heads are iron 049s. Any opinions?
    If they're irons, chances are they're not going to change much at all. The ex valves may tighten up a little depending on the valve material, but I'd start at .018"-.020" int and .022" -.024" ex.
    If God is your co-pilot, change seats!
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    Senior Member Factory1's Avatar
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    Ha! I beat you Steel, your getting slow old man!!!

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by Factory1 View Post
    All iron isn't going to grow nearly as much as aluminum, so the numbers should be close hot vs cold. .024 intake/ .026 exhaust are really common hot numbers, I wouldn't go much under that. Im just guessing here but I would think all iron would expand .004 to .006, I wouldn't cold lash it under .018 myself intake or exhaust.
    Quote Originally Posted by steelcomp View Post
    If they're irons, chances are they're not going to change much at all. The ex valves may tighten up a little depending on the valve material, but I'd start at .018"-.020" int and .022" -.024" ex.
    What, are you guys sitting together sharing a sundae???...

    You ever recomend + .001 on the exhaust?

    GT
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Senior Member EVILFORCE's Avatar
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    O O. If you have a tight lash cam and it is running .020 or more you will beat it to death. They run .010-.014 normally. How does it sound at its current adjustment? If correctly adjusted you wont hear much noise. If it is fairly quite at that .020 I would set them at .022 and .024. See how that sounds. If it is quite you might be ok. Without the cam card it is just experience. Sorry I can't help anymore then that. And I would set those hot. .022 intake and .024 exhaust. If it rattles all to hell try .012 and .014. You can destroy your valve train if not set up right.
    No Fool Like A Old Fool is there?

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    Senior Member Ronboats's Avatar
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    Thanks for the help, guys!

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    Senior Member Factory1's Avatar
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    Quote Originally Posted by GT Jets View Post
    What, are you guys sitting together sharing a sundae???...

    You ever recomend + .001 on the exhaust?

    GT
    What do you have your spy goggles on Glenn? Steel quit eating all the caramel!
    Usually + .002 on the exhaust.....

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    Senior Member Ronboats's Avatar
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    Quote Originally Posted by EVILFORCE View Post
    O O. If you have a tight lash cam and it is running .020 or more you will beat it to death. They run .010-.014 normally. How does it sound at its current adjustment? If correctly adjusted you wont hear much noise. If it is fairly quite at that .020 I would set them at .022 and .024. See how that sounds. If it is quite you might be ok. Without the cam card it is just experience. Sorry I can't help anymore then that. And I would set those hot. .022 intake and .024 exhaust. If it rattles all to hell try .012 and .014. You can destroy your valve train if not set up right.
    I don't notice any valvetrain noise,but it's pretty loud, so it's hard to tell for sure.

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    Senior Member EVILFORCE's Avatar
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    Quote Originally Posted by Ronboats View Post
    I don't notice any valvetrain noise,but it's pretty loud, so it's hard to tell for sure.
    Well if it is a tight lash cam and you are running it at 22 and 24 you will hear it. Put something on the valve cover and it will be hammering. Odds are it is a normal cam.
    No Fool Like A Old Fool is there?

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    Senior Member Factory1's Avatar
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    Dig up the thread in here about flattened cams and oil & additives. A high quality oil will reduce the valvetrain noise.

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    steelcomp was here
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    Quote Originally Posted by Factory1 View Post
    Ha! I beat you Steel, your getting slow old man!!!
    LOL...old is good...don't forget that. Better right, than fast.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    steelcomp was here
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    Quote Originally Posted by GT Jets View Post
    What, are you guys sitting together sharing a sundae???...

    You ever recomend + .001 on the exhaust?

    GT
    Guess I'll give the kid the cherry...probably never had one....

    Two things to consider on lash. Heat and expansion (or the lack there of) and the lobe design. One we know, the other we don't in this case. It's always better to be on the tight side of recommended...as long as the valve closes and there's enough seat time for heat transfer, the rest is academic. Most of the time tighter lash will settle down valve train harmonics and reduce valve bounce which most people mistake for thinking you need a bigger cam. Too much lash, like the guy with the fat broads in his avatar said, can destroy a tight-lash cam, and cause unneeded noise and harmonics in a normal cam. The .002" added to the ex side typically allows for the extra expansion of the ex valve from seeing more heat, so .001" probably isn't enough. I am definitely not a fan of excessive lash.
    What's most important than the actual lash setting is consistency from valve to valve. If you;re off a few thou from recommended, that's OK, but they all need to be consistent, whatever numbers you choose.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    Senior Member Ronboats's Avatar
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    OK, how hot is "hot" when adjusting the valves? I can recerculate water with a bucket and bring the temp up to whatever I need, but I only have temp guages on my heads. I fried the normal temp guage but thats another story. What is a good temp for the heads to read for adjusting? Also what would be a normal running "in the water" head temp ?

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