Comp XE-R lobe base circle vs. stock

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Feb 21, 2006 | 05:39 AM

#41

TAQuickness

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From: Houston

Quote:

Originally Posted by GuitsBoy

Is this a bad joke? I cant see those muffler bearings requiring .160 shorter pushrods.

You forgot about the resonance coupled plasma discharges...

Quote:

Originally Posted by Patrick G

Pushrod checker is not the answer I'm looking for. I'm looking for the base circle cam dimensions of a Comp XE-R cam and how that compares to stock. Even more importantly, how that base circle dimension change affects pushrod selection, if at all compared to stock.

According to the PR calculator in the cam guide sticky, if you changed only your cam, from stock (1.533") to a XER lobed cam (1.400"), you would need a PR length of 7.477 (assuming stock length was 7.400). My experience has proven there are more variables in the valve train than the spreadsheet takes into account. In fact, the spread sheet said I needed a 7.429" PR...

Feb 25, 2006 | 03:17 AM

#42

mr2guru

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From: Kansas City Area

Back to the original question....

I just got a comp cam 247/252 .647/.644 113 and my base circle is 1.378/2= .689

Are the lobe types somewhere on the cam card.... only thing I could see that would be it is 4784R/4445F ???

Feb 25, 2006 | 07:29 AM

#43

HavATampa

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From: Louisiana

4784R/4445F are the intake/exhaust lobe types for that cam mr2guru. I measured a Comp Cam XER cam with lobe types of 3725R /3728R and the base circle measures 1.452 and my stock cam measures 1.553. Real close to what Sidestep posted and I'm using a not so accurate digital caliper from Harbor Freight.

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