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Author Topic:   Cam Questions ?
Kromulous
Member
posted May 28, 2004 08:47 AM
New to racing, and racing engines. So i got a couple questions about cams concerning race engines.

1. Whats advancing the cam do? effect the power band?

2. What does "install it on a 102" mean, concerning lobe seperation?

Any help would be appreciated, thanks.

dirtbuster
Member
posted May 28, 2004 09:41 AM
advancing the cam will move the power band down in rpm a few hundred. retarding the cam will move the power band up in rpm.

Installing on 102 means the intake centerline is installed at 102 degrees. If you have a cam with 106 degrees lobe seperation then installed at 102 would be 4 degrees advanced. intake at 106 would be straight up. The 102 really has nothing to do with lobe seperation it is just the installation point of reference. You could theoretically install any cam at 102 and it wouldnt matter what the lobe sep was.

nw15
Member
posted May 28, 2004 10:12 AM
I think the question is....is the cam already advanced to 102 so all you have to do is line up the timing marks or do you need to advance it by moving the lower gear to the 4 degrees advanced position.???


Kromulous
Member
posted May 28, 2004 11:44 AM
Thanks Dirtbuster, thats what i needed to know.

So if i got a 106 cam, and its recomended by a engine builder to install it on a 102, that would mean i would advance it 4 degrees to lower the powerband, got it. Thanks !

Is it common to advance the cam? Seems like nice engine tuning tool to me, especially if you dont want to tach your bottom up to run with the full ability of the cam (Eagle bottom end / stk blk and 8500 rpm range cam), is my thinking right here?

dirtbuster
Member
posted May 28, 2004 12:41 PM
Remember that some cams come ground with advance already into them so you need to check your cam card to see what the intake centerline is ground at. Also timing sets can be off one way or the other. Thats why you really should degree your cams to make sure.

Advancing or retarding 4 degrees will prob only move your power band a few hundred rpm. If you have a cam that runs to 8500 and you only want to turn 7500 then you need a different cam.

waltonjr1
Member
posted May 28, 2004 01:58 PM
This lobe seperation centerline deal used to really confuse me. After a lot reading I finally figured it out, maybe this will help some one else who is confused. If the intake centerline and exhaust centerline are the same on the card the cam has no advance therefore the lobe seperation is also 106. If the intake is 106 and the exhaust is 114 the cam is advanced 4 degrees from the factory and this would meen your seperation is 110. An easy way to figure your seperaton is to add the intake and exhaust center and divide by two, this will give you your sep. Also whatever your degrees in difference is between your intake and exhaust you divide it by two and thats how many degrees advance your cam is ground from the factory. Most of you prob know this already but maybe it will help someone, I know it had me confused for a while.

[This message has been edited by waltonjr1 (edited May 28, 2004).]

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