how can i tell what ratio rocker i have

[64 200 ranchero]

i bought a tri power head a few months ago off a forum member and it came with a rocker arm, the head was a fully ported race head with all sorts of strange modifications. i recently noticed that the rocker arm has a completely round shaft, as to where my other set has a flat spot that runs along it. so whats up with that?

 

[bubba22349]

Is it an early head? Pictures would help too.

 

[64 200 ranchero]

it was a flat top head prob a 69 since it didnt have hardened valve seats, the rockers are adjustable, ill try to get pics

 

[bubba22349]

On the rockers just measure the short side and long side with a little math you have the theretical ratio that it mult. the lift of the cams lobe and pushes at valve stem.