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Hi All we are getting the cyl's bored out this week and just recieved out pistons. Thanks to Buff Harsh and Wiseco! we are running todd henning pistons and a megacycle 123-20 grind cam. We are having the cam gear slotted so we can degree the cam in but We were wondering if anyone had any ideas on advance or retard #'s. we are going to run this on the street but want to utlize the parts in the motor. what sugestions do you all have for us?
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Megacycle always has cam timing numbers for their cam. NEVER depart from these numbers by more then 1/2 of a degree. You take the chance of major engine trouble.

As a matter of fact, you can't even do the head work properly until you degree in the cam, and check valve to piston clearance, piston pocketing, valve spring binding etc.

Cheers,
Jordan
 

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yes, follow what it says. or call mega and ask. they have experience with those cam/piston combos. although sometimes they are total dicks. you will need to check your clearances before making any of those decisions though. like jordan said. i havent been involved with setting one up for a while, but i think i remember 80 thou being a good clearance. but dont go by that. im just guessing on it from back when. make sure you check everything really closely. its easy to start one up and bend a valve with that piston/cam combo.

jc
 

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When Mega cycle regrinds cams....specially the more performance oriented cams....if I'm not mistaken they often include cam advance into the regrind....meaning, installed at their specs it's already advanced when compared to the OEM camshaft. Advancing the OEM, or just degreeing them, has always been a method for gettting more hp...but when a cam is reground, if suitable specs are found in their research for various other cam parameters, they will include that "advance" into the regrind.
The Mega cycle cams I've checked usually have one set of lobes spot on...the other is sometimes 1/2 degree off or less (twin).
I set up my pistons with about .065 piston/valve on the intake and about .075" on the exhaust...not a lot of room for changing cam timing there.
One day I'll modify the cam sprocket for adjustment and play with an engine on the bench to see how the clearances work out....but then it would have to be all tested on the dyno to find out if it's working.
JohnnyB


PS. When I say "spot on" I mean to the megacycle specs, not the OEM specs.


Edited by - jbranson on Feb 03 2007 1:22:57 PM
 
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