Valve Lash
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Valve Lash

  1. #1
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    Default Valve Lash

    So my cam calls for .024-.026 Int. .026-.028 Exh. Where do these numbers come from?

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    Senior Member f_inscreenname's Avatar
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    Rocker to valve stem gap. It must be a solid cam? You numbers seem a little high though. Mine needs .017 gap.
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    Quote Originally Posted by f_inscreenname View Post
    Rocker to valve stem gap. It must be a solid cam? You numbers seem a little high though. Mine needs .017 gap.
    Yea, solid roller...they want these numbers cold, my old cam I set at .016 cold

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    Quote Originally Posted by Gone Green View Post
    Yea, solid roller...they want these numbers cold, my old cam I set at .016 cold

    Are you sure that's for a cold setting?
    I know mine calls for a hot setting, but it's easy enough to figure out what they should be set cold too, depending on head and block combinations.

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    Senior Member ol guy's Avatar
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    iron block, aluminum head. the metal combo would help also who's cam and specs. Some cams and grinders call for a different cold settings. For what it's worth I have never set a roller warm. Reason is how would you get the engine warm without setting lash first? Also is it a billet or iron roller??? Mark

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    Quote Originally Posted by ol guy View Post
    iron block, aluminum head. the metal combo would help also who's cam and specs. Some cams and grinders call for a different cold settings. For what it's worth I have never set a roller warm. Reason is how would you get the engine warm without setting lash first? Also is it a billet or iron roller??? Mark
    Yes, iron block, aluminum head, it was an Isky Billet reground..I always set mine cold also, those #s just seem alittle loose
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    Default cam

    Fwiw. I would start at .017 intake .018 exhaust. fire it and while it's warm do a recheck. I have never ran a solid roller that loose. Back in the day there was a duntov cam solid grind iron cam (not a roller) that called for a .030 lash. You could hear it big time. I closed it down to a .020 .020 and the engine ran alot better. Point being at times you need to play with lash to make things work. With a roller there is no reason for that loose a lash especially with a roller cam. MLAO. Mark I would check with the grinder first.
    Last edited by ol guy; 03-29-2017 at 07:31 PM. Reason: add-on

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    Interesting, maybe a cam grinder will chime in...this is a solid roller. My old Crane had the same numbers but those were set cold.
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    My cam calls for 24 int. 26ex. as well. On my aluminum head deal, I set them 20/22 cold due to the head 'growth' when fully warmed up. I've checked them hot and they were right on the 24/26 called for. Every engine combo is different, but alum . Heads grow about 4-5 thou. and thus open up the valve lash. Steel heads do not grow nearly as much. JMO, Jocko

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    Default Valve to piston??

    No one ask what the clearance is before, during and after overlap. That loose "recommended" setting will have more of an affect on duration than lift.. Tighter lash means the valve "event" starts sooner, and ends later. Just a small, .002-.004 type change can change the duration quite a bit. Large changes away from the grinder's recommended lash will change the cam's basic numbers..
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    Quote Originally Posted by Gone Green View Post
    Yea, solid roller...they want these numbers cold, my old cam I set at .016 cold
    we check 'em cold, but set 'em hot. because.. it's aluminum, and the heads don't come with some kind of guarantee they will get hot in a uniform manner. you can set them cold, but with an aluminum head they will be 4 to 6 thousandths looser than when you set them. so you're looking at .030-.032 hot, which seems awfully loose. if you want to set them cold, make sure you check them hot.

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    Quote Originally Posted by bp298 View Post
    we check 'em cold, but set 'em hot. because.. it's aluminum, and the heads don't come with some kind of guarantee they will get hot in a uniform manner. you can set them cold, but with an aluminum head they will be 4 to 6 thousandths looser than when you set them. so you're looking at .030-.032 hot, which seems awfully loose. if you want to set them cold, make sure you check them hot.
    This cam is one that Barry-Obnoxious had ground for me...I thought the numbers seemed high..so Barry called his grinder, he said this cam calls for 28/30 hot and Barry said start at 20/22,I am going to dyno this and check hot
    Thanks Guys

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    Quote Originally Posted by Gone Green View Post
    This cam is one that Barry-Obnoxious had ground for me...I thought the numbers seemed high..so Barry called his grinder, he said this cam calls for 28/30 hot and Barry said start at 20/22,I am going to dyno this and check hot
    Thanks Guys
    If you have enough dyno time, you can change the adjustment some and and what it does to your curve, after all your other tuning is set.

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    Quote Originally Posted by obnoxious001 View Post
    If you have enough dyno time, you can change the adjustment some and and what it does to your curve, after all your other tuning is set.
    Will Do...the machine is mine for 8hrs

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