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valve drop calculation/conversion?

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Old 03-25-2008, 07:49 PM
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Default valve drop calculation/conversion?

I am waiting on a call back but I am no patient today LOL

A certain brand head has .175 valve drop with their 243 casting with 64cc chambers, 2.02/1.57 valves.

Now, with that exact same head milled down to 59cc chambers what would be the new valve drop?

Thanks

Brian
Old 03-26-2008, 10:36 AM
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got the call back and the answer is .155 not sure on the math formula used to arrive at the answer.
Old 03-26-2008, 01:07 PM
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Originally Posted by red fury
got the call back and the answer is .155 not sure on the math formula used to arrive at the answer.
Red I am sure the math is something like this. To get ls6 heads to 59 cc you need to mill about .030 off of them. So with a .175 stock and then milled to 59 cc you would have .175 - .030 = .155.
Old 03-26-2008, 02:14 PM
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Sig, you damn engineer... I will call you with my future math questions LOL. John is working on some math to figure out what cam we can fit in their. I wouldn't mind just using the F7 since I like to hit it with the 175shot, but I think John is gearing more for the F13 if it will fit.
Old 03-27-2008, 05:06 PM
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Except 1.75-.30= 1.45, NOT 1.55 so the math must involve some more numbers, right?

Maybe it only take .20" to get a LS6 head down to 59CC...
Old 03-28-2008, 04:08 PM
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Good catch! LOL once they make it to my house I will just bring them to John @ FMS so he can "double check" the drop. I may just leave my current cam in and pick up a couple more N20 goodies
Old 03-28-2008, 08:58 PM
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Originally Posted by red fury
Good catch! LOL once they make it to my house I will just bring them to John @ FMS so he can "double check" the drop. I may just leave my current cam in and pick up a couple more N20 goodies
I guess I just ran the numbers too quickly. I wonder if they are taking less off the heads.
Old 03-28-2008, 10:33 PM
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I just wanted to add that I didn't mean to sound like a douche; I sometimes get wrapped up in writing the post and attitude is hard to transfer across the 'net.
Old 03-29-2008, 01:05 AM
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The math isn't that easy, you have to acount the vavle angle. Witch changes the "drop" as its not 1-1 ratio of material removed off the deck. (strait mill)
Old 03-31-2008, 09:11 PM
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I believe, not sure though that it would be

T*cos^-1(VA)= change in valve drop

where T is thickness cut off the heads and
VA = valve angle.
Old 03-31-2008, 09:54 PM
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Originally Posted by Alvin
I believe, not sure though that it would be

T*cos^-1(VA)= change in valve drop

where T is thickness cut off the heads and
VA = valve angle.
This is good info, so for a 15 degree valve angle you lose .0013 of valve drop for every .001 you mill from the head?




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