Rocker arm ratios

[NorthernSwede]

Hi! I've heard and read (on this site among other sources) that the stock rockerarm ratios is quite alot under the 1,5 they're supposed to be, but both mopar performance and sealed power makes stocklooking rockerarms for the small-block chrysler, the question is - are these true 1,5 ratio or just as far off as the stock ones?

Oh and by the way, what's the difference between a left and right stock rockerarm? What part number is right and what is left? :-s

 

[1970Duster]

Yeah there is the difference (I think the real ratio is 1.44~) if you go order up a new set of roller rockers (from Hughes, comp for sure) they will be whatever ratio they post (1.5=1.5, 1.6=1.6, etc). I would suggest running 1.6 with a smaller cam vs 1.5 with a bigger cam.

 

[Sport 360]

Hi! I've heard and read (on this site among other sources) that the stock rockerarm ratios is quite alot under the 1,5 they're supposed to be, but both mopar performance and sealed power makes stocklooking rockerarms for the small-block chrysler, the question is - are these true 1,5 ratio or just as far off as the stock ones?

Oh and by the way, what's the difference between a left and right stock rockerarm? What part number is right and what is left? :-s

They are stamped steel, not very accurate. Rollers have a true ratio and make your cam perform like it should. Imagine having a cam where all the lobes are slightly different, each cylinder would be using different pressures and the engine would not perform at its best. This can be what happens although the average street car wouldn't notice anything.
Left and right are slightly different, you can see where the push rods go on each one.

 

[Locomotion]

Even with "true" 1.5, 1.6, etc. ratio aftermarket rocker arm, you won't get the advertised cam lift. You're losing a little bit through the inefficient angles between lifter, pushrod and rocker. But it will be fairly close and the engine will perform better.

I wouldn't consider stamped rockers for much over mild performance applications. Stamped rockers have also been known to get punched through by the pushrods when running too much pressure for too long. Aftermarket adjustables are a performance gain just from proper adjustments as well.