contentsunderpressur

What is the difference in 1.6 and 1.7 rocker arms? I have a 89 lx 5.0 and I'm thinking about putting a set of GT40X heads on it and a Z cam from Ford Racing. The heads call for a bolt on rocker and they offer these two types. I don't know the difference in the two or which I should go with.

GT4HUTCH

perhaps i'm not the best at explaining this but i'll give it a shot. a 1.7rr wil lift open the valves further than a 1.6rr. You can take the lift of int. and ex. lift of your cam profile then multiply it by the rr ratio to get your total VALVE lift.

GT4HUTCH

BTW. check the max valve lift on your heads and piston to valve clearance. If you go with 1.7's you may need reliefs cut in the pistons.

contentsunderpressur

I think I'm going with the 1.6s then. The cam I want to use has a int and exhaust lift of .552 and the springs are only rated to that so I don't want to add any more lift than I have to. Thanks for your help.

HACKGT350

the rocker ratio will give you your total lift. you take your cam lift and multiply it by the rocker ratio weather its 1.6 or 1.7. now you choose the one you want by how close it gets you to your heads max lift/flow point, and you dont need to have all 1.6 or all 1.7. sometimes you need a 1.5 on the intake side to reach max lift of your heads and a 1.7 on the exhaust to reach max lift on that side. when i built my 350 chevy for class i had 1.5's on the intake an 1.6 on the exhaust to get my max lift of the head to get my max flow. do some research you might want to change your cam in the end

mjr46

1.6's will be fine go with them and convert the heads to stud mount

contentsunderpressur

Why convert them to stud mount? Can't I just get the bolt on 1.6s and be done? Which is better and why.

HACKGT350

studs are better, they are much stronger.

contentsunderpressur

Ok, adjust the rockers on the studs just like the old chevy 350s? If they call for a gap how big?

jtmustang

hey there how do u convert a 1.6 lift ratio to when u throw 1.7's on it isnt it like .030 more but i would like to know how to figure that out i lost the calculator for this.