Push-rod length
Thread Starter
Instructor
Joined: Nov 2012
Posts: 114
Likes: 5
From: Fowlerville Michigan
Push-rod length
I'm looking for opinions to make sure the length I'm getting makes sense.
Basics are LS6 heads, no milling, TSP Torque V2, stock rockers, .040" head gaskets, LS7 lifters.
I have the comp cams push rod checker and am following vettenuts' process here: https://www.corvetteforum.com/forums...ow-to-use.html
When the length checker is at 7.200 (8 turns) I have a little vertical play.
I turn the checker another half to 8.5 (I have to remove it every time, I can't get my fingers in there) to 7.225 and there is no longer a "click" when I pull up and down, but it does allow side to side movement.
Assuming a .075-ish preload for LS7 lifters, I should be looking for 7.300 push rods. This seems way short. I thought TSP used a smaller base circle and I would need longer push rods.
Any idea what I could be doing wrong?
Basics are LS6 heads, no milling, TSP Torque V2, stock rockers, .040" head gaskets, LS7 lifters.
I have the comp cams push rod checker and am following vettenuts' process here: https://www.corvetteforum.com/forums...ow-to-use.html
When the length checker is at 7.200 (8 turns) I have a little vertical play.
I turn the checker another half to 8.5 (I have to remove it every time, I can't get my fingers in there) to 7.225 and there is no longer a "click" when I pull up and down, but it does allow side to side movement.
Assuming a .075-ish preload for LS7 lifters, I should be looking for 7.300 push rods. This seems way short. I thought TSP used a smaller base circle and I would need longer push rods.
Any idea what I could be doing wrong?
Last edited by BMan0660; Nov 10, 2016 at 04:12 PM.
Thread Starter
Instructor
Joined: Nov 2012
Posts: 114
Likes: 5
From: Fowlerville Michigan
Also, I did this with both the intake and exhaust. Turned the engine over by hand a couple times and nothing changes. I'm reading you need .050" short pushrods for higher cup on the LS7 lifters, but where would I be losing the other .050"?
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Smaller base circle requires longer pushrod because the lifter is now sitting lower in the bore and the rocker hasn't moved relative to the head but the head has move lower due to the gasket. One thing to be very careful of with new lifters is that when you measure the plunger doesn't depress at all. Not sure on the LS7 lifters, but my Morels were very easy to depress the plunger when they were empty so measuring was tedious.
Drifting
Joined: Mar 2000
Posts: 1,956
Likes: 135
From: Maryland
When I installed the TSP 228R cam I also ended up with shorter pushrods than stock. TSP said not to worry about it and trust the length checker. They suggested that possibly GM may be using a different amount of preload.
Four years and many HPDE's later and it still going strong!
Four years and many HPDE's later and it still going strong!
