Rocker sweep on the valve

[LB9GTA]

I'm having a problem determining what is the best for shim to use for my LGM shaft rockers for minimum sweep on the valve and best pattern in the middle of the vavle

I have a sbc 421 with AFR 245 heads,using a 5/16 valve and LGM shaft rockers (1.7 int and 1.65 ext).

With the thick shim (0.1") , I have a sweep of 0.77"int & 0.72"exh, and 0.6" off the edge of the valve(int) and 0.69" ext.
With a 0.125" shim , I have a sweep of 0.58"int & 0.58"exh, and 0.49" off the edge of the valve(int) and 0.68" ext
With a 0.150" shim, I have a sweep of 0.56"int & 0.57"exh, and 0.55" off the edge of the valve(int) and 0.55" ext

Seems like it wants less shim to get it centered on the valve, but then it makes the sweep bigger.

I'm going to call Shelton @ LGM tomorrow, but anyone have any advice?

[statsystems]

Narrow sweep is more important than centering the sweep. Sounds like the shafts want to go up. And back.

[LB9GTA]

Yah, that's what the instructions say too.
"Mimimum sweep" is best.

Maybe Shelton will give me some more insight.

[turdwilly]

LGM rockers are designed using the same "low pivot" geometry as Jesel, as opposed to mid-lift geometry. And BTW you left out a "0" after the decimal on your sweep measurements

[lekid]

LGM uses low pivot like Jesel??

Sheldon as always been a preacher of the 1/2 lift geometry setup, so I am surprised that he would have his rockers setup the Jesel way vs the 1/2 lift since that is what he recommends?

[turdwilly]

All I can tell you is when I spoke with him on the phone while setting up the SBC 1.6 rockers I got from him, he told me his rockers were designed using the Jesel low-pivot geometry.

[MadBill]

Not to say this makes it the only viable choice but geometrically, no matter what the other variables, 1/2 lift will give minimum sweep and anything else will have more.

[LB9GTA]

Talked to Shelton today.
He said go for the minimum sweep as long as it's in the inner 2/3 of the top of the valve.
Minimum sweep 1st, placement 2nd

[rustbucket79]

I have T&D shafts on my AFR 245's and they run on the intake side of the tips, maybe .030" or so inboard of the centreline.

Are you planning to dyno?

[LB9GTA]

Yes hopefully dyno in a month

[LB9GTA]

LGM rockers are designed using the same "low pivot" geometry as Jesel, as opposed to mid-lift geometry. And BTW you left out a "0" after the decimal on your sweep measurements

D'oh! Just noticed that now. Oops

[rustbucket79]

Don't forget to post the results, there just isn't much press on these heads.