[btp76]

I understand the differences and advantages to increasing rocker ratio. If I use Harland Sharp 1.65 rockers on Canfield heads will there be any drastic geometry problems other than needing custom pushrods?

[lluciano77]

Why do you need custom pushrods? The only thing you need to worry about is that the pushrod has clearance at the pushrod slot.

I was going to get the Harland Sharp 1.65s. I got my 1.6 Ersons for $50 so I went with them.

[NXS]

the reason for longer pushrods is b/c the roller tip travels in an arc. This arc needs to follow the valve stem and stay centered as best as possible thruout the arc.

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Well in this pic i have the arc angles wrong but the idea is to have the roller tip centerd at half lift.

[bracketeer]

Valve train geometry from Comp cams
http://www.compcams.com/information/Products/Pushrods/

[lluciano77]

Still, I think the pushrod length he had before will be the same. You always need to check tip travel with new valvetrain components, but for the most part the original lengths should work.

[bracketeer]

I never could understand why people use high ratio rockers unless they have cam to rod clearance problems. I have seen people put .488 cams with 1.6 rockers. Why not just buy a .500 cam and save the money on the rockers. The cam doesn't cost any more. Or, you get people putting 1.6 rockers on stock heads because the deck is too short for a large cam. They don't breathe anyway. Why the big cam?

[btp76]

Don't have pushrods yet, may as well make sure it's right.

Why higher ratio rockers?

Heads flow well to 600 lift. With a solid flat tappet cam I can run a less aggressive lobe and make up the lift with the rocker.

[lluciano77]

The benefit of running higher ratios is that you get more lift compared to duration.

[underdog305]

The way I undestand it is.. You get approx 2 more degree's of duration on opening and 2 more degree's @ closing ( 4' total approx increased duration) as well as .030" more lift with 1.6 rockers.