what rockers?
 

what size rockers should i use with my combo (basicly just a cobra intake and 65mm tb) i was going to go 1.7s but am afraid that it will move the hp curve to high in the rpm range and i would loose low end torque. on the other hand would 1.6s be worth the time and money?

Re: what rockers?
 

If you have the stock cam then 1.7 roller rockers would be a good upgrade. Your power band will not be affected.

Re: what rockers?
 

I run 1.7 cranes they were cheap, and i saw a good gain, they also work good with my e-cam i have now.

Re: what rockers?
 

1.7 go for it, more lift for you.

Re: what rockers?
 

I was under the impression that you would base your rocker size off of your cam? So, if you are running a stock cam, larger rocker arms will just put more stress on your valve springs, or even force your duration to go too far causing many other issues that would need to be dealt with. Someone please correct me if I am wrong.

Re: what rockers?
 

Naw, as long as the springs fit your application, 1.7's wont lift a stock cam a whole lot more, but when i went to the e-cam, it was time for springs, also it depends on how old yours are.

duration shouldnt be affected, just lift.

Re: what rockers?
 

Stock cams have .444/.444 lift. With 1.7s, it will be .472/.472, still well within the .500 max lift for the stock springs, but with the higher lift, high rpms may see increased valve float.

Duration is changed by changing the ratio of the rockers, just not very much.

Since duration is measured at either .003 (Ford advertised) or .050 lift, the amount of time the valve lift is at that .003 or .050 will be changed. I doubt it would be enough to report an extra degree on the .003 simply because you're dealing with such a minor multiplier (1.0625) when going to 1.7s.

E-303

.498/.498 220*/220* @ .050 Adding 1.7s opens the valve just a little more than what it used to be open so when it was at .048 of lift before (and not counted for duration), it'll now be at .050 (and counted for duration). You may see another degree or two of duration or so.

Re: what rockers?
 

how much of a power gain would i see? 10-15 hp or less?

Re: what rockers?
 

good info unit.

Well to give you a good idea, i went 13.5 At 99 on a stock motor, with 1-5/8 headers, cai, stock cam and stamped rockers. put the 1.7's on and went 13.2 at 101, so you can expect 15-20 hp.

Re: what rockers?
 

I went with 1.7 RR's using a .456 lift CC hydraulic cam. That made it .486 lift with no problems. Not sure on power increases, but sure didn't hurt anything.

Rev