samdogmx

iTrader: (13)

about 145-150 shipped

SS_bnoon_SS

iTrader: (3)

That F-ing sucks... I ordered my set of 16 LS7 exhaust rockers on Feb 3rd from gmpartsdirect.com and am still waiting for them to ship!!! Who did you order yours from?

samdogmx

iTrader: (13)

ordered mine from a guy on one of the other forums i visit frequently that works at a GM dealer.

ap2002

iTrader: (8)

so what was the final decision on these, are they going to work???

Yelo

I wouldn't use the LS7 rockers if I were you, my guess is that the revised valve angle on the LS7 is what requires the different length rocker....change the valve angle and you change the location of the valve tip in relation to the rocker

BenKey

iTrader: (1)

I'm with you. Change that and you won't have what you started with. All this just to save a couple of hundred bucks over a set of aftermarket 1.8s. Not worth the effort, IMO.

SS_bnoon_SS

iTrader: (3)

Only the intake valve is offset, not the exhaust side. Try again. My guess is that samdogmx did not mock them up with long enough pushrods and/or shims to move the swept area onto the correct portion of the valve stem.

Yelo

I didn't say OFFSET, I said REVISED VALVE ANGLE.....as in a 12º valve-stem angle on the LS7 compared to the current LS1's 15º valve angle, if you change the valve-stem angle in relation to the deck surface you change the distance from the valve tip to the rocker mounting boss....thus requiring a longer rocker arm. It's basic geometry

SS_bnoon_SS

iTrader: (3)

The intake valve has the revised angle of 12 degrees, requiring offset rockers on the intake side only of the new LS7's. The exhaust valve is on the same valve angle as all LSx bsaed engines. That's why we need 16 exhaust rockers to work with our engines. Your basic geometry is correct, you're just not fully informed of what parts we're trying to use and why.

Yelo

Taken from Popular Hotrodding:

"Taking the racing cues of a higher port entry and a flatter valve angle, the intake ports have been substantially raised at the manifold face, while the valve angle has been changed from the 15-degree angle of other engines in this family, to a more advantageous 12-degrees. The ports themselves have been significantly enlarged, aided by the use of offset intake rockers, moving the pushrods adjacent to the intake runners outward. The pushrod pinch, commonly a point of cross sectional constriction in the intake ports has been eliminated. Overall, the port cross section has been enlarged, in keeping with the requirements of high-rpm torque production with a large displacement engine."

The Intake Rocker was offset to allow the pushrod and the valve to contact one another....The cam lobes are in the same position as other LSx engines but the pushrods have been moved ofer to allow a larger port neccesitating an OFFSET rocker on the intake side !!!

For the exhaust side of things:

Taken from Corvettemuseum.com

"The heads feature 70-cc combustion chambers that are fed by huge, 56-mm-diameter titanium intake valves. The lightweight titanium valves each weigh 21 grams less than the stainless steel valves used in the LS2, despite the valve head having 22 percent more area. They are complemented by 41-mm sodium-filled exhaust valves (vs. 39.4-mm valves in the LS2). To accommodate the large valve face diameters, the heads' valve seats are siamesed; and, taken from experience with the engines of C5R racecars, the LS7's valve angles are held at 12 degrees - vs. 15 degrees for the LS2 - to enhance airflow through the ports."

And.....

"To accommodate the extremely high valve lift and the large ports, 1.8:1 roller rocker arms - offset on the intake side - and raised valve spring seats are used. In contrast, the LS2 has 1.7:1 conventional roller rockers."

BOTH Intake AND Exhaust valves are at a 12º angle.....If you change the angle of the valve-stem relative to the deck surface you change the location of the valve-tip relative to the rocker boss......which requires a LONGER rocker arm to reach the valve!!!!!

I'd bet everything I know about these motors on this info.....there is NO other reason for a longer rocker arm than the valve-tip being moved furthur away from the rocker-boss, and the 3º change in valve angle is enough to cause the 1/8" or so difference in rocker-arm length