DrocheGMC

I have an 01 GMC Sierra 4.8 apart right now getting a TSP Cam, TSP PRC Heads, and Long tubes. The cam is in, the heads are on, and push rods and rocker arms are also in. I bought one of the Kits from TSP so they pick the most common push rod length for the specific setup which in my case ended up being 3.75. I measured the push rods and they seems to be the correct size, however when the motor is at top dead center the rocker arms on cylinder 1 are tight, but on cylinder 3 and 5 they have some back and forth lash. I can not remember if this is normal for the life of me and definitely want to hear what you guys have to say.

01SilveradoJakee

Always check pushrod length. I would say any play there is bad, as far as when i did my cam and few of my buddys, I never had any play in the rocker arms and pushrods. The checker is like 20 bucks from Comp.

DrocheGMC

Yes I have the push rod tool a they look to measure at 3.75 but am obviously going to check again, kind of surprised that I may need stock size push rods or longer with milled heads.

01SilveradoJakee

Pushrod length depends on multiple items. the OD of the cam, if the lifters were pumped up with oil or if they were collapse at the time you measured, rocker arms, so many things come into play. I always double check mine.

DrocheGMC

if the lifters bleed down would that cause the up and down lash in some of the cylinders

01FormulaTA

iTrader: (16)

none of the rockers should have ANY play when they are all torqued down and the most common size is 7.4, not sure where you are getting 3.75??

DrocheGMC

Total typo on my part, 7.375, a 3.75 would be an a very short push rod haha.

But when Texas Speed sets up their kits they send the most commonly used pushrod length paired with the specific cam and head. They sent me 7.375 but it appears I need larger. Just wanted to make sure that the cylinders always have some sort of pre load on them.

I apologize for the typo

Skip Fix

Yes.Hydraulics will, obviously solid lifters do not but you set lash on them.

2002_Z28_Six_Speed

iTrader: (20)

How much lift does the cam have?

I actually ended up with a longer pushrof after I installed my texas speed heads do to an aftermarket casting and .6" max lift.

DrocheGMC

They are PRC stage 2 Heads milled .30 and the cam is a 220r, .600 lift, and a 110 LSA. Not a very big cam at all. Still haven't had the chance to measure again, but I will definitely need longer push rods.