['71ElCamino]

I am wanting to install some roller rocker arms on my 71 Elky w/350. What is the stud size; 3/8" or 7/16"? Also, is it a 1.5 ratio, or 1.6 ratio (stock)?

I am leaning towards the summit brand, simply because they are cheaper. Any pro's or cons about these?

 

[BillsCamino]

Stock SBC rocker is 1.5 ratio on a 3/8" stud.
On a stock or mild performance application, installing aftermarket roller rockers of the same ratio will see no HP gains.

 

[novaderrik]

stock stamped rockers spec out at 1.52 or soemthing like that, but they are said to vary from 1.45-1.55 or so.
since you are buying parts, and if your cam isnt' already too big, then get some 1.6 rocker arms. the cost is the same, but it does add a bit of lift and a few degrees of duration to the cam that's in it. if your cam is .450 lift with the stock 1.5 ratio, then it will be .480 with nothing but changing the rocker to 1.6.