Tech Tip Tuesday! How to measure your LS for proper Length Pushrods
Now, go easy on me here guys lol. I'm probably the worst teacher in the history of ever. I'm not good at explaining how to do things. But, hopefully, between this video and the following list of instructions, you'll learn how to measure for the proper length pushrod in your LS powered ride.
Why even worry about it? Why not just use the 7.400" length that most cam kits come with? A lot of times you can. A lot of times, that isn't the optimum length for your particular setup. Improper length pushrod, whether it be too long or too short, can cause anything from loss of power to catastrophic failure. So, no harder of a task than this is, its worth it to check for at least your peace of mind.
What you'll need:
Pushrod length checker (COMP 7702)
Intake and Exhaust rocker
Basic math skills (or a calculator lol)
Step 1: Pick a cylinder. #1 usually works fine. Get to the base circle of the cam.
Step 2: Turn your pushrod length checker out 10 full turns and then insert into pushrod hole (each full turn is .050")
Step 3: Put rocker on the rocker stand and run the rocker bolt down until its tight against the rocker. Not torqued, but not loose.
Step 4: check for 'play' in the rocker arm. If it has up and down movement (if you can tap the nose of the rocker on the valve stem) the pushrod is too short and you'll need to remove it and turn it out at least another half turn. You want just a little bit of side to side movement with no lash. Follow these steps until your rocker looks like mine in the video.
Step 5: Once you have the pushrod length checker adjusted correctly, you'll figure out the proper length pushrod with this calculation:
Take the # of turns and multiply that number by 0.050” Add 6.80”. (This is the length of the checker) Now add lifter preload (preload dependent on your particular lifter) This is your pushrod length
Example: 11.5 (turns) x 0.05” = 0.575” + 6.8” = 7.375” +0.075”(my lifters recommended preload)= 7.450”
Step 6: Repeat this procedure for the exhaust side
Step 7: Order pushrods
Step 8: Install pushrods and then torque rocker bolts to 22ftlbs
It's that simple! Hope this helps. As I mention in the video, I'm sure someone will come along and tell me how I'm wrong. This is how I do it and have had success in doing so with quiet valve train and good horsepower! Be sure to drop a comment on the video if this helped you out or ask some questions if its still a little fuzzy!