Pushrod length
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Pushrod length I'm getting a little confused reading advice on the correct measuring for pushrod length.
I have converted an LS7 lifter to be solid I am reading a length of 7.300" counting turns of the adjustable length checker (a few rods are measuring +/- 1/8th of a turn of the 10turns most are) to reach zero lash on all 16 valves.
When switching the lifters across to the LS7 lifters I will be running and measuring preload a on Cylinder 1 Intake with a 7.350" pushrod from zero lash 7/8th of a turn and 7.375" pushrod 1 1/8th of a turn to reach 30Nm.
But then checking Cylinder 7 Exhaust that measured the same 7.300" with a solid lifter is giving me 7.350" pushrod from zero lash 3/4th of a turn and 7.375" pushrod 7/8th of a turn to reach 30Nm.
I am thinking from this with both measuring close to 1 turn with a 7.375" pushrod that would be the correct length, but coming across conflicting information saying turns should being a range of values from 1/4 - 3/4 turn, 1/2 - 1 turn, 1/2 - 1 1/2 turns or 3/4 - 1 1/4.
I am a little confused though why when measuring with a solid lifter, they're reading the same but with LS7 hydraulic lifters they're giving 2 different values though. could I be missing something with testing the hydraulics.
I have converted an LS7 lifter to be solid I am reading a length of 7.300" counting turns of the adjustable length checker (a few rods are measuring +/- 1/8th of a turn of the 10turns most are) to reach zero lash on all 16 valves.
When switching the lifters across to the LS7 lifters I will be running and measuring preload a on Cylinder 1 Intake with a 7.350" pushrod from zero lash 7/8th of a turn and 7.375" pushrod 1 1/8th of a turn to reach 30Nm.
But then checking Cylinder 7 Exhaust that measured the same 7.300" with a solid lifter is giving me 7.350" pushrod from zero lash 3/4th of a turn and 7.375" pushrod 7/8th of a turn to reach 30Nm.
I am thinking from this with both measuring close to 1 turn with a 7.375" pushrod that would be the correct length, but coming across conflicting information saying turns should being a range of values from 1/4 - 3/4 turn, 1/2 - 1 turn, 1/2 - 1 1/2 turns or 3/4 - 1 1/4.
I am a little confused though why when measuring with a solid lifter, they're reading the same but with LS7 hydraulic lifters they're giving 2 different values though. could I be missing something with testing the hydraulics.
Last edited by vy_ls1; Mar 5, 2026 at 02:57 AM.
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Joined: May 2016
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From: St. Louis
What parts are you using? Most if not all aftermarket camshaft have a smaller base circle then stock and require a longer push rod then stock. Also look at the lifters you're using and see where the cup sits in the lifter body compared to the old ones. Most of the time unless the heads are milled significantly you wouldn't need a shorter push rod
Thread Starter
Teching In
Joined: Jan 2012
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Parts list -
Lifters - Genuine GM L7
Cam - Crow cams 1249 1713147943.871249SpecSheet.pdf
Heads factory 241 castings, were machined and valve seats done
valve springs - crow dual springs VTKLS8.
Block was also machined - machine shop didn't provide specs on how much they machined off the block or heads.
overall lifter length is the same. cup depth is measuring about 0.010" higher on the LS7 lifter than the stock ones.
I annoyingly seem to have misplaced the factory pushrods or have thrown them. seem to have every other part from the tear down in the shed except the pushrods.
Lifters - Genuine GM L7
Cam - Crow cams 1249 1713147943.871249SpecSheet.pdf
Heads factory 241 castings, were machined and valve seats done
valve springs - crow dual springs VTKLS8.
Block was also machined - machine shop didn't provide specs on how much they machined off the block or heads.
overall lifter length is the same. cup depth is measuring about 0.010" higher on the LS7 lifter than the stock ones.
I annoyingly seem to have misplaced the factory pushrods or have thrown them. seem to have every other part from the tear down in the shed except the pushrods.
