INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

Quick Q: Measuring Base Circle.

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Old Dec 11, 2006 | 06:37 PM
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Default Quick Q: Measuring Base Circle.



Did i measure it right? I took calipers and found the base circle to be 1.47 on my 224/226 cam. Lobes are XER/XE. If i call Comp will they give me the exact numbers? I really need to know this!
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Old Dec 11, 2006 | 06:39 PM
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Sounds about right, and yes comp will tell you the exact base circle too.
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Old Dec 11, 2006 | 06:57 PM
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Comps tech dept rocks.... they are awesome.... they will tell you whatever you need to know
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Old Dec 11, 2006 | 07:07 PM
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Both intake and exhaust were 1.47?
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Old Dec 11, 2006 | 07:15 PM
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Originally Posted by Sport Side
Both intake and exhaust were 1.47?
I could be wrong and i was using a shitty plastic dial caliper.
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Old Dec 11, 2006 | 07:17 PM
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LOL, I wasn't calling you out... Just curious. Interesting none the less. I haven't had the chance to measure, and it doesn't go exactly with what I had told you earlier.

Glad you checked.

Guess I ought to measure mine, once it comes back. Off at the cam pro right now.
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Old Dec 11, 2006 | 07:20 PM
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Not to tryin to sound like an idiot, but why is this measurement important?
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Old Dec 11, 2006 | 07:24 PM
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Given this, you can measure proper pushrod length. My heads are milled .045" and my cam now is on a 1.42" base circle using a 7.400." I need to know in order to either install my cam or to get new shorter pushrods.
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Old Dec 11, 2006 | 07:25 PM
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Originally Posted by BlackGMC
Not to tryin to sound like an idiot, but why is this measurement important?

THE BASE CIRCLE IS WHAT YOU HAVE TO SET WHERE THE LIFTER RIDES, AND YOU HAVE TO GO SMALLER FOR A BIGGER LLOBE OPENING OTHERWISE THE LOBES WOULD BE SO BIG THEY WOULDNT GO THRU THE CAM BEARINGS.... SO THE MEASUREMENT IS IMPORTANT, BECAUSE IF YOU CHANGE IT THEN YOUR VALETRAIN GEOMETRY WILL BE THROEN OFF, AND YOU WILL MOST LIKELY HIT THE VALVE IN TEH WRONG SPOT, OR JUST CAUSE BINDING...

LONG STORY SHORT.... IS ALL THE PIECES ARE NOT MATCHED UP IT BECOMES VERY PAINFUL TO YOUR WALLET...
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Old Dec 11, 2006 | 07:33 PM
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Beau... I Believe Your Measurement Is Off.... If You Look At The Circle Taht The Cams Closed Surface Runs On.... Thats Your Base Circle.

If You Look Where It Passes The Apex Of Your Lobe Opening....

It Is Below .600 Looks Like Its About .550-.575 On The Graph Which When You Take That X2 It Comes To 1.1 Or 1.15 " I Would Call Comp To Make Sure But 1.4 Is Definitely Not Correct... Unless Of Course Taht Pic You Have Is Not Of Your Cam


Gimme Your Cam Number If It Is Off Teh Shelf... I Can Probably Figure It Out...... If It Is A Custom Grind You Will Have To Call Them
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