quick question about rockers
Thread Starter
Pro
Joined: Nov 2012
Posts: 672
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From: Chesapeake Virginia
quick question about rockers
Hey all,
I'm building a mild performance 383--- aluminum heads, 190cc runners, 64cc chambers, springs good for .600 lift, guides, screw in studs.
running 10.5:1 compression.
Comp XE256H, flat tappet cam, new lifters, probably new pushrods too, 110* lobe sep, 256/268 duration, .447/.454 lift--- (I know this is a small cam but I wanted more torque than upper RPM range).
is it advisable to re-use the original stamped rockers?
if not, and I need to get new ones, is there any benifet to getting roller tip or full roller rockers? I mean, any value there considering the flat tappet cam?
also, if I get new rockers, should I go with the 1.5's or up to the 1.6's?
thanks,
I'm building a mild performance 383--- aluminum heads, 190cc runners, 64cc chambers, springs good for .600 lift, guides, screw in studs.
running 10.5:1 compression.
Comp XE256H, flat tappet cam, new lifters, probably new pushrods too, 110* lobe sep, 256/268 duration, .447/.454 lift--- (I know this is a small cam but I wanted more torque than upper RPM range).
is it advisable to re-use the original stamped rockers?
if not, and I need to get new ones, is there any benifet to getting roller tip or full roller rockers? I mean, any value there considering the flat tappet cam?
also, if I get new rockers, should I go with the 1.5's or up to the 1.6's?
thanks,
Last edited by Jig A Low; Jan 17, 2013 at 01:30 PM.
Race Director
Joined: May 2006
Posts: 18,736
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the stock ones do not give a true 1.5 ratio closer to 1.37. The Competition Cams roller tip give a true 1.52. For the 1.6 you have to check clearances in the head since the push rod is moved.
Read this link concerning the true ratio
http://www.camaros.org/302valves.shtml
Read this link concerning the true ratio
http://www.camaros.org/302valves.shtml
Last edited by MelWff; Jan 17, 2013 at 03:17 PM.
Burning Brakes
Joined: Sep 2012
Posts: 818
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From: coon rapids mn
you need long slot rockers.check out comp cams cam quest 6,the ex268h should make more tq/hp .aluminum heads allow you to 1/2 more point of compression .what intake are you using ?if it has provisions for rear coolant lines ,use them.
Intermediate
Joined: Feb 2012
Posts: 28
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Since the rocker arm swings through an arc, the ratio does not remain constant. The article referenced by MelWff mentions the 1.37 ratio as the actual ratio at the lash points for stock rockers. The ratio at the max lift is what we are discussing here, which would be the 1.44 number provided by the stock rocker arms discussed by the article.
I just want to point out the correct math so someone doesn't think they will go from 1.37 to a greater ratio with new rocker arms. Based on the measurements by the author of the article, you should improve from the 1.44 ratio provided by the stock rockers at max lift.
So, I believe MelWff is correct in theory, just needed to fine tune the actual number.
I just want to point out the correct math so someone doesn't think they will go from 1.37 to a greater ratio with new rocker arms. Based on the measurements by the author of the article, you should improve from the 1.44 ratio provided by the stock rockers at max lift.
So, I believe MelWff is correct in theory, just needed to fine tune the actual number.
