Strick

Because the LT4 roller rockers are not adjustable, what happens when you go to a GM hot cam?

tombrammer

I am sure the LT4 roller rockers are adjustable. http://www.grandsportregistry.com/lt1vslt4.htm scroll down to the LT4 roller rockers and see the nut and locking nut inside that is used to adjust the preload.

Tom400CFI

I don't believe the stock valve train on the LT4 is adjustable.

I see the nut, but that proves nothing, other than that it has a nut to hold the rocker from falling off.

Going to a Hotcam, I assume that the base circle is the same, and the lobes are taller, so one could get away with the same pushrod length and rocker position. But maybe you need to shim the rockers?

i probably shouldn't have responded since I don't' have first hand experience here.

Silver96ce

Per the FSM at page 6-61 there is no adjustment for LT4 rockers - you just tighten the rocker arm stud nut to 18 ft. lbs.

rklessdriver

Factory LT4's use a stepped 10mm stud and there is no adjustment.

The GM Performance Parts LT4 rocker kit uses a 3/8 stud and they are adjustable.

The GM Performance Parts Hot Cam is ground on a base circle so that the heel of the cam lobe is the same distance as the factory cam - that way the lifter pre load will be the same when a factory GM LT4 rocker is TQ'd down against the stepped stud.
Will

Tom400CFI

Guess I wasn't too "out to lunch".

mtwoolford

the GM Hot Cam is designed as a drop in replacement; don't worry about adjusting the valves...they are nonadjustable; love it or not ..it is what it is.

l98tpi

I did a LT4 hot cam kit in my rebuild on my LT4. We got the complete GMPP hot cam kit and used the cam and new springs. Make sure to use the new springs on the kit. They are higher rated springs. I just re used the stock rockers and sold the new ones in the kit.