Stock Rocker arm ratio or is it?

[Meathead]

Are stock rocker arms ratio 1.1? How can you tell what ratio you have if you don't know if it is stock or not?

[Marc]

Stock through 1964 was 1:1 - all engines (12/13/15/1600) got 1.1:1 from `65 up, there are two parallel raised ridges on one side of those rockerarms. But the same raw parts were used to create the aftermarket 1.25:1 rockers that CB Performance sells (really just the stock part for the Brazilian SP2 sports car engine) - all they did was machine the cup for the pushrod as close to the fulcrum point as practical...if the cups are roughly centered in the material they're stock, if they're obviously displaced up you've got CB 1.25s.



There are also entry-level 1.25s sold by EMPI and SCAT which aren't based on the stock piece (neither has OEM markings) - I don't have a picture of those but hopefully the above information will suffice to identify what you have.
"Real" ratio rockers, which come with shafts and support stands that have offset holes to shift the rocker assembly down and keep the pushrods centered in the tubes, will have the adjusting screw on the pushrod end rather than on the valvestem end so they can't be mistaken for stock.

[Steve Arndt]

Great post Marc.