[Houston54]

I confess to not knowing much about rocker ratios and related matter but am wanting to move to roller rockers on my SBC built with Edelbrock Peformer cam, manifold, and carb.

I am running s reworked 993 iron heads with dished pistons.

Am thinking of using the stamped rocker arms with the roller tips.
The stock ratio is 1:5. What would going to 1:6 do for me?

What size stud do I most likely have in these heads? 3/8 or 7/16?

[DoubleVision]

The heads have 3/8 studs. Moving up to a 1.6 ratio rocker will raise the lift by .030, and the move the duration up by about a degree. Example, if the lift is given at .450 with a 1.5 ratio rocker, the 1.6 will make it .480.
However, make sure you use a quality name brand like Crane, Comp cams, isky, etc. the off shore brands like proform are a bit cheaper, but the quality is less and the ratio isn`t accurate, you get what you pay for. factory rockers are reliable but aren`t accurate either, they are given at 1.5, but there really around 1.4.

[Blazin72]

If you go to the higher ratio rockers make sure the pushrod doesn't contact the head along the side of the pushrod hole. You may have to elongate that hole a bit.

[xxllmm4]

Don't waste your money with roller tip rocker arms, they wont give you any more HP, go full roller or stamped. DoubleVision is right, you get what you pay for. A lot of times the price difference isn't that much if you shop around.

If you go from 1.5 to full roller 1.6 you should get someting like 10-15hp.

One last note, I would never trust aluminum rocker arms on a street car, get a set of comp cams pro magnum roller rocker arms.

Jordon