Chevy Small Block Part 12 - PT. 12: Rockin' Ratio

Testing Different Exhaust Rocker Arm Ratios

Mike Petralia Sep 1, 2003 0 Comment(s)
Sucp_0309_07_z Chevy_small_block_part_12 Roller_rocker_arms 1/6

COMP Cams offers its Pro Magnum roller rocker arms for small-block Chevys in both 1.5 and 1.6 ratios. Previously, we had found the most average power using 1.6 rockers on all valves. This month we tried 1.5's on the exhaust only and got little in return.




Sucp_0309_08_z Chevy_small_block_part_12 Main_goal 2/6

Our main goal for this whole test was never realized. We wanted to run COMP's 1.3:1 (PN 1012-16) special break-in rockers on the exhaust to see if the reduction in lift would make more power as some claimed. But, in order to decrease the ratio, the rocker arm's pushrod cup must be moved away from the trunion centerline. This in effect caused the pushrod to hit the cylinder head (note top of pushrod in photo). Had we not checked for this interference and ran the motor, power would have been down tremendously and damage could have resulted. Always check for proper pushrod clearance when installing new rocker arms or changing ratios.

Test: 25 Swapped COMP Cams 1.5:1 Pro Magnum roller rockers on exhaust only

We're always looking for new ideas. Do you have a better one for Danger Mouse? Send your test suggestions to:

Super Chevy MagazineAttn: Danger Mouse720 Hundley WayPlacentia, CA 92870Or Email: mike.petralia@primedia.com

Sources

Westech Performance Group
Mira Loma, CA
951-685-4767
WestechPerformance.com
Comp Cams
Memphis, TN 38118
800-999-0853
http://www.compcams.com
SX Performance
St Louis, MO 63143
314-644-3000
http://www.sx-performance.com
Russell Performance Products
Daytona Beach, FL 32114
904-253-8980
www.russellperformance.com

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