ok the problem is 2 of my cylinders dont have comp with the rockers tq at 22lbs back off a 1/2 turn and they have comp.all the rest are fine my set up is 243s milled 40,xxxs, used ls7 lifters, and comp mag pushrods 7.400 and muti layer gm head gaskets and stock rockers and cradle. everyone says that the pushrods is to long...but if that was the problem none of the cylinders would have comp right?? but its only 2 that im having trouble with. machine shop guy said the 2 lifters may be pumped up and once i start the motor they should let go anyone ever delt with this?? im ordering a pr tool today to double check. this is my first rebuild so im learning as i go....

 

I would get a pushrod checker

 

Agreed! you can not just guess based on what some one else did. It's not un- common for the deck surface of the block to be different. Heads are also cast and can have variations in them too... Usually when you mill a head you also need a shorter push rod to compensate.

 

I completely missed the milled heads part. Your pushrods are going to be too long I'm sure. Buy a checker and measure and order your new pushrods.

 

Just curious but which two cylinders?. And is this engine in a vehicle yet?

 

I'm running 243 heads milled .030 with a .040 head gasket and I had to use the 7.350 push rods. Do what these guys said and buy a push rod checker for like $20. It takes all of the guess work out of the equation.

 

hes running a z06 cam which if its part#5308 the 204/218 it has a .025 smaller base circle
he basically copied my setup 243s milled .040 with z06 cam in a 5.3 with ls7 lifters..stock block
i run stock pushrods with no issues and valvetrain is quiet like stock
IF the his pushrods were to long it wouldnt just have issues on 2 cylinders

 

###update### my pr were too long,,,,they were 7.450s and i need 7.400s,

so i have a new 0 mile set of comp magnum pushrods 7.450 forsale $100.00 obo

 

I'm planning on rebuilding my 5.3 using GMPP CNC ported LS6 heads, and a new cam. My question is will an LS2 cam work in the later model 5.3? Please help.

 

dont think so cam senser is in the wrong spot...in timeing cover vs on the block like a 5.3