samdogmx

iTrader: (13)

can you explain to me how longer pushrods will make the tip of the rocker contact the valve at a different location while the fulcrum is still remaining in the same location? Im not giving up on these yet, but I dont know what to do to move the contact point.

BTW has any of you other guys that orderd these got them yet?

TurboGibbs

iTrader: (6)

You can move the actual contact point with the valve slightly with a different length pushrod if you have fully adjustable rockers. You actually change the height of the fulcrum. The LS7 rockers arn't fully adjustable thus that theory won't work.

SS_bnoon_SS

iTrader: (3)

It certainly will, it just requires shims. Adjusting rocker swept area on the valve stem is not uncharted territory.

BTW, Yelo, it doesn't matter about the valve angle. The short side of these rockers are the same length as stock. The only way to make a 1.8 rocker fit these engines is either to build one with a shorter-short side and make the long side about the same as stock, or to slightly change the geometry with shims and/or longer pushrods to change the attack angle on the valve stem. I'm sorry if my info on the intake/exhaust angle was incorrect, but it's a mute point anyway...

TurboGibbs

iTrader: (6)

I guess I should have been more clear. I don't know for sure of course, but the amount of shims it looks like it will need would require a longer rocker bolt and the shim, unless custom machined, could cause instability.

Yelo

Between the cost of shimming and new longer custom-length pushrods you are probably looking at the same cost as buying a decent set of 1.8:1 aftermarket rockers that will work with everything you have now.

And, the valve angle is NOT a moot point here...the whole 2nd half of this thread is about why these rockers aren't contacting the valve at the correct location !!!, While there ARE ways to make these work (shimming and longer pushrods) the fundamental reason behind why they don't just drop in is because of the revised valve geometry.

TurboGibbs

iTrader: (6)

Usually with aftermarket heads, when they change the valve angle they change the rocker mount as well. For reasons we do not know, GM engineers decided to change the rocker instead of the rocker location. Sucks.

samdogmx

iTrader: (13)

so how much would i need to shim them up? any ideas of were to start?

Yelo

Try stacking .010" shims until you get to the proper alignment. You *may* end up with the rocker tip at an out of spec angle to the valve-tip if you have to shim too far though, it shouldn't be too far out of whack though.

You'll have to get an adjustable pushrod to measure what pushrod length you need though......

SS_bnoon_SS

iTrader: (3)

So a 15 degree valve angle 1.8 rocker would be different somehow? Riiiiiiiiiiiiiiight...

Yelo

YES...actually they would be different there bud....because aftermarket LSx 1.8 rockers are DESIGNED FOR THE APPLICATION THEY ARE BEING USED ON !!!!!!!, they have taller rocker bosses, offset pivot points and shorter pushrod to pivot point lengths........................

We are trying to make parts that were designed for a DIFFERENT ENGINE SERIES work on our motors......yes, there is enough similarity that parts LOOK the same, but NO-ONE knows whether or not they will FUNCTION the same until it gets tried.

If you refuse to agree with me that's your choice......but insulting my intelligence and being derogatory towards me in your posts is NOT the way to prove to me or anyone else that you're right, all that does is reduce my respect for you............