Rocker Arms

Here’s an excerpt from an upcoming Y-Block Magazine article that may shed some light on the subject.

Ted Eaton (3/13/2019)

ROCKER ARMS
Rocker arm testing on the 312 dyno mule with ECZ-G heads showed that increasing the ratio from 1.4:1 to 1.54:1 was worth 3HP in peak values. Switching again from 1.54:1 to 1.6:1 was worth another 3HP. There were no measurable differences between the Dove, Harland Sharp, and Rocker Arm Specialist 1.6:1 roller rockers when all testing variables were kept constant. Rocker arm weight does not appear to be a variable that makes a performance difference in this particular testing instance. Had the valve springs been marginal in their setup pressures, then the rocker arm weights might have been an issue. The base peak HP was 267 with the 1.4:1 rockers, 270HP with the 1.54:1 rockers, and 273HP with the 1.6:1 roller rockers. This particular round of testing was performed on the 312 dyno mule with the Edelbrock #573 3X2 intake with Stromberg 97’s and a set of stock unported and unposted ‘small letter’ G heads. In this test, consider the 1.54 rockers being worth a 1.1% gain over stock while the 1.6 rockers would be a 2.2% gain over stock 1.4’s.

But what happens when the rocker arm ratio is changed up on the Mummert aluminum heads? Switching from the 1.54:1 rockers to the 1.6:1 roller rockers saw a gain of 12 HP. That’s pretty significant. If you are dealing with ported iron heads, then look for much more than a 3 HP gain as better breathing heads simply responds more favorably to rocker arm ratio increases.

And on the shaft mounted rocker arms, common hot rodding practice has been to replace the springs that hold the rockers in place with some form of machined bushings to maintain the rocker arms in their respective positions. Upon dyno testing two different engines on the dyno that had the springs replaced with machined bushings, both engines lost 2½ horsepower. Keeping the bounce or free movement minimal with rocker arm shaft springs does appear to be an advantage over using some form of machined bushings in their place. I would surmise that the springs act as a damper to keep ‘free’ rocker arm movement minimal on those camshafts that require a lash adjustment.

Lorena, Texas (South of Waco)

Author	Message
Ted	Posted 5 Years Ago
Co-Administrator Group: Administrators Last Active: 8 hours ago Posts: 7.2K, Visits: 203.0K	Here’s an excerpt from an upcoming Y-Block Magazine article that may shed some light on the subject. Ted Eaton (3/13/2019) ROCKER ARMS Rocker arm testing on the 312 dyno mule with ECZ-G heads showed that increasing the ratio from 1.4:1 to 1.54:1 was worth 3HP in peak values. Switching again from 1.54:1 to 1.6:1 was worth another 3HP. There were no measurable differences between the Dove, Harland Sharp, and Rocker Arm Specialist 1.6:1 roller rockers when all testing variables were kept constant. Rocker arm weight does not appear to be a variable that makes a performance difference in this particular testing instance. Had the valve springs been marginal in their setup pressures, then the rocker arm weights might have been an issue. The base peak HP was 267 with the 1.4:1 rockers, 270HP with the 1.54:1 rockers, and 273HP with the 1.6:1 roller rockers. This particular round of testing was performed on the 312 dyno mule with the Edelbrock #573 3X2 intake with Stromberg 97’s and a set of stock unported and unposted ‘small letter’ G heads. In this test, consider the 1.54 rockers being worth a 1.1% gain over stock while the 1.6 rockers would be a 2.2% gain over stock 1.4’s. But what happens when the rocker arm ratio is changed up on the Mummert aluminum heads? Switching from the 1.54:1 rockers to the 1.6:1 roller rockers saw a gain of 12 HP. That’s pretty significant. If you are dealing with ported iron heads, then look for much more than a 3 HP gain as better breathing heads simply responds more favorably to rocker arm ratio increases. And on the shaft mounted rocker arms, common hot rodding practice has been to replace the springs that hold the rockers in place with some form of machined bushings to maintain the rocker arms in their respective positions. Upon dyno testing two different engines on the dyno that had the springs replaced with machined bushings, both engines lost 2½ horsepower. Keeping the bounce or free movement minimal with rocker arm shaft springs does appear to be an advantage over using some form of machined bushings in their place. I would surmise that the springs act as a damper to keep ‘free’ rocker arm movement minimal on those camshafts that require a lash adjustment. Lorena, Texas (South of Waco)
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Ted	Posted 5 Years Ago
Co-Administrator Group: Administrators Last Active: 8 hours ago Posts: 7.2K, Visits: 203.0K	2721955meteor (3/11/2019) I have a set new rocker shafts, refaced rockers, 1.5s, blocked off drain tubes. I want $250 for a pair . If you want to use spill tubes, easy change. My opinion feed to all rockers important for camshafts and eliminates sludge build up at end away frome tubes. I should use the classified but can't get any help removing items. Freight won't be much. cliff ct1940@shaw.ca The ability to delete posts was removed as that activity was being abused. If an object sells or is being removed from a placed classified ad, then simply add a post to the thread that the object is ‘SOLD’ or whatever. If wanting to sell those rocker arm assemblies, just post them in the Classifieds section. Putting that info within the middle of a non classifieds thread will not get the required exposure. Lorena, Texas (South of Waco)
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Rocker Arms

Rocker Arms

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