rocker arm upgrade

[chiaronate]

hi guys. i've been thinking of changing the rocker arms on my '94 gt mustang. i think stock rockers are 1.6 ratio, correct me if i'm wrong. i thought i'd get 1.7's, and was wondering if i would have to change anything else. any idea of how much horsepower increase? would my torque peak be at a different rpm? would 1.7's affect lobe separation? these questions probably sound dumb, but i really am cam iliterate. any help would be appreciated, thanks.

[302man]

Replacing the stock rockers for a set of cranes 1.7's will probably get you a tenth at most. Usually they will allow you to shift just a tic deeper in the rpm range.

[HotRoddin]

Originally posted by chiaronate
these questions probably sound dumb, but i really am cam iliterate. any help would be appreciated, thanks.

Not at all dumb questions Chiaronate. Very technical questions !
Questions that I sure don't know all the answers to, but basically whats really happening is your moving the pivot point of the rocker closer to the push rod which means for the same amount of movement at the pushrod, the rocker tip (thus the valve) will move further. So increasing the ratio gives you more lift from the same cam ... it also gives you a bit more duration, although i still haven't figured out why on the duration part
To answer your question, yes 1.7's will push your torque curve a bit because effectively its just like putting in a higher lift longer duration cam. I don't think it will effect lobe seperation because thats ground into the cam but i could be wrong because it doesn't seem like it should change the duration either but it does ?
Cam specs are figured on the stock ratio for the engine you're dealing with ... for ford small block thats 1.6
If you want to figure how changing the ratio will change your lift heres a formula.
Divide the lift of the cam by the original rocker ratio (which gives you the lobe lift), then multiply this number by the new rocker ratio.
For example, the stock Mustang 5.0L HO cam has .444” at the valve. Divide this number by the stock rocker ratio of 1.6 to get the lobe lift, .2775” and multiply by the new rocker ratio 1.72, to get the new lift of .477 ( the formula I found at fordmuscle.com)

[chiaronate]

thanks for doing the math for me! i thought i'd have to do it. any idea how much horsepower and torque i would get with 1.7's? would i have to change anything else, like the springs, or could i just install the rocker arms by themselves?