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Author Topic: Cam Caps  (Read 2792 times)

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Offline minimikee

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Cam Caps
« on: Dec 6, 2007, 07:36PM »
Hey all, I just purchased myself an R4 cam from pinsair second hand  ;D

I've been hunting around the forum trying to find out how much must be machined off the cam caps to accomodate the new profile but i havent found a definitive answer  ???

How much must be taken off the top of the caps??
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Offline dozer

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Re: Cam Caps
« Reply #1 on: Dec 7, 2007, 07:53PM »
 ??? nothing ??? why would the cam caps need changing, the profile of the cam is the lobe shape isn't it.
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Offline FuzzyDropbear

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Re: Cam Caps
« Reply #2 on: Dec 8, 2007, 12:41AM »
In Noss' "Install your cam tutorial" he says that the caps need to be machined.

I thought the machining would only change the lobe shape too. Not sure why you have to machine the camps. I'm interested in an answer too as I'm considering an R4 cam and some other mods to my pinny soon.
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Offline Ammerty

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Re: Cam Caps
« Reply #3 on: Dec 8, 2007, 01:49PM »
lol man i wanna go over to QLD just to see how ya TRX is gonna be - your purchasing mods left right n center
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Offline dozer

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Re: Cam Caps
« Reply #4 on: Dec 8, 2007, 02:06PM »
if it needs machining it would be for a fresh surface for the cam to turn on, but wouldn't the head need machining too, to accomadate the slightly larger diameter should the cam need it?
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Offline minimikee

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Re: Cam Caps
« Reply #5 on: Dec 9, 2007, 06:20PM »
the tutorial goes on about how the top of the caps im pretty sure must be machined down to prevent the lifters ticking, doesnt it say because the profile has changed the lifters at some point of rotation lose contact with the cam or did i read that wrong lol.

Quote from: Ammerty on Dec  8, 2007, 01:49PM
lol man i wanna go over to QLD just to see how ya TRX is gonna be - your purchasing mods left right n center

lol maybe  :P
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Offline minimikee

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Re: Cam Caps
« Reply #6 on: Dec 14, 2007, 08:50PM »
Does anyone know how much must be machined off??
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Offline SSS

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Re: Cam Caps
« Reply #7 on: Dec 19, 2007, 10:02AM »
I honestly don't remeber how much was machined off my caps. You need to measure the base circle diameter of a stock cam and subtract the base circle measurement from your new cam. Divide that number by 2, and *i think* that is how much needs to be machined.

Between 0.02" & 0.05" is not uncommon.

Dozer, when using hyd lifters, the caps need to be machined as the base circle of the cam is usually a little smaller after the cam is ground, this difference needs to be made up either by reducing the height of the caps or using lash caps of given thickness on the valve stem tips.
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