measuring rocker ratio

[oddiesGN]

Is there a way to measure rocker arms to find out what ratio they are? What do I do to figure out ratio? My HS don't have any ratio # stamped on them and would like to be sure they are what I think they are.

Otes.

 

[charlief1]

Yes, but...you have to get the diameter of the shaft and find the center. Then measure the distance from the center of the fulcrum (roller) to the center of the shaft, as well as the center of the pushrod location to the center of the shaft. Then some simple division and you've got it.

 

[oddiesGN]

Yes, but...you have to get the diameter of the shaft and find the center. Then measure the distance from the center of the fulcrum (roller) to the center of the shaft, as well as the center of the pushrod location to the center of the shaft. Then some simple division and you've got it.

Does any one know the math used to get the answer? Getting the measurements is pretty easy, just need to know what to do with those numbers.

Thanks, Otes.

 

[charlief1]

Just like doing fractions. 1/8" is 1 divided by 8 or .125". so if the short side is .125" and the other side is .250" then it would be 125 divided by 250 which is .5.

 

[oddiesGN]

Ok, that should be easy enough.

Thanks, Otes

 

[bison]

It's better to measure lobe lift then measure valve lift and do the division. You get an exact number that way.

 

[big reazon]

Did you get them from bison? If so they are 1.65s

 

[oddiesGN]

Did you get them from bison? If so they are 1.65s

No I didn't get them from Bison. I'm probably 100% sure they are 1.5 ratio I trust the guy I got them from. I was just curious since I didn't see a number stamped on them so it got me thinking on how can you tell if it doesn't say on them, also could help me in the future. Always looking for knowledge never know when it could come in handy.

Otes.

 

[turbofabricator]

I agree with Bison. The most accurate way would be to measure lobe lift (written on cam card) then measure valve lift (with a dial indicator and a solid lfter on the cam--because a hydraulic lifter will compress under the weight of the valve spring) You can get close by just measuring the fulcrum diameter, "guessing" the distance from center of push rod to center of fulcrum. (guess because it'll be tough to get an EXACT measurement) and then "guess" the measurement from center of roller tip to center of fulcrum and then "do the math". The closer the pushrod is to the fulcrum centline, the higher the ratio is.

 

[bison]

I agree with Bison. The most accurate way would be to measure lobe lift (written on cam card) then measure valve lift (with a dial indicator and a solid lfter on the cam--because a hydraulic lifter will compress under the weight of the valve spring) You can get close by just measuring the fulcrum diameter, "guessing" the distance from center of push rod to center of fulcrum. (guess because it'll be tough to get an EXACT measurement) and then "guess" the measurement from center of roller tip to center of fulcrum and then "do the math". The closer the pushrod is to the fulcrum centline, the higher the ratio is.

You can take the rocker off and measure off the pushrod. The lift at the valve can be slightly altered by the geometry too.

 

[turbofabricator]

You can take the rocker off and measure off the pushrod. The lift at the valve can be slightly altered by the geometry too.

Geometry?? Oh MAN......I hated that in college. Good call on the lift measurement at the pushrod.