Rocker arm ratios

I have a set of Eddy Victor heads with Hughes offset intake rockers and crane gold exhausts. I measured at the retainer with a dial indicator on the cranes and i am getting .020 more lift than what i should be getting . Lobe lift is .410"/.414" using 1.6 rockers should be .656/.662 . I am getting .682 on the exhaust and .632 on intake. My lobes measure out with +/- .001-.002 . The cranes are stamped 1.6 but this is closer to 1.65? The hughes are closer to 1.55. I figured it might be my accuracy in measuring but they are pretty even across both sides?

And your question is?

Are you using real springs or checking springs?

...because if you are using checking springs the rocker arm manufactures build in extra ratio to compensate for deflection. It is typical to see artificially high lift numbers at the valve with a light checking spring.

Signed,

apt pupil

My one experience with Hughes rockers, and it was the older version without the slot down the middle.......
Std offset BB rockers, EZ heads, 1.6 ratio.....just under 1.6 with a checking spring, about 1.51-1.52 with 600lbs of spring load.

My experience has been that Cranes are usually about .05 higher than advertised when measured with a checking spring.

the crane 1.6's I've measured were 1.65. there are some variables but all the cranes I've checked had ratios higher than their rating.

That's about what I'm getting. I am not using checking springs. I have checked them 10 times each thinking I was crazy. I am using the old style Hughes also would have figured they would be s little more accurate since not produced on a scale as large as cranes.

The rocker ratio will vary slightly over the length of travel. The stated ratio may have been with a specific lobe height.

I was using the way Hughes suggests for measuring for new push rods when i figured this out. If i multiply the lobe lift by the ratio on the cam card it comes out to what they are calling the lift numbers. That just blows my mind, that they could be off. Kinda hard to pick out a cam when you are relying on ratios to be true.

I've check a bunch of different rocker arms for ratio at the retainers, even the good ones will vary some in the same set
I've seen T&D single shaft sets vary .030 at the retainers, same on some of the older Harland Sharp sets.
The older ductile iron sets sold by all of the cam company are horrible also, same on the extruded aluminum sets