Checking ptv
Thread Starter
Teching In
Joined: Feb 2016
Posts: 36
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From: Jacksonville
Checking ptv I got checker springs, adjustable pushrod, and a dial guage. I took some old lifters apart and make them solid for testing purposes.
i measured 7.33” for zero lash/preload on the rocker arm.
question: if I’m going to use hydraulic lifters with .070” preload, do I measure ptv with preload or zero lash, do I use the 7.33 or 7.4” pushrod for checking
i measured 7.33” for zero lash/preload on the rocker arm.
question: if I’m going to use hydraulic lifters with .070” preload, do I measure ptv with preload or zero lash, do I use the 7.33 or 7.4” pushrod for checking
Zero lash because that will be the maximum travel possible.
Pushrod length used doesn't really matter as long as the rocker is riding on the valve tip in the appropriate position.
Pushrod length used doesn't really matter as long as the rocker is riding on the valve tip in the appropriate position.
Last edited by LLLosingit; Dec 19, 2018 at 08:16 PM.
Thread Starter
Teching In
Joined: Feb 2016
Posts: 36
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From: Jacksonville
The whole reason for using the solid lifter is so that no preload comes into play. With a solid lifter every bit of the cam lift will be used to push the valve down to it's lowest point.
TECH Junkie
Joined: Nov 2013
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From: White Bear, Mn
To check PTV, as long as the checker springs are in place, you can use the adjustable pushrod for measurement. I assume you are using the dial indicator and the 2 degree crank rotation method and not the clay method for measuring.
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Thread Starter
Teching In
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From: Jacksonville
ive been doing it wrong and adding preload on to the solid lifter
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Here's the procedure I wrote for myself. I made a gasket that was 0.040" thick from my removed MLS gasket by removing one of the layers. I ultimately installed 0.040" Cometics so this was an accurate representation. Install the head and tighten down snug before starting. I had check springs on cylinder #1 and installed two solid lifters that were thorough lubed so they would move easily. The may stick in the up position so as you move the piston up you need to push down on the rocker to make sure it doesn't contact the piston since the valve is at an angle. Note that I ensured that my wipe was correct on the workbench with rocker shims prior to measuring. I have posted how to do this several times. Measurements are made at 2 degree intervals from 20 before the piston is at TDC to 20 degrees after. It takes some time to do this and you need a degree wheel set on the crank.Write down each measurement and the PTV will be apparent and this will also let you know where the piston is at the minimum. Measurement is made by pressing the rocker so the valve touches the piston. The dial indicator will provide the distance. You need to set the dial indicator at mid-stroke since you will be measuring downward and zero prior to each measurement. After completing this measurement I followed up with a clay measurement.
WARNING: Ensure lifter is down during crankshaft movement to prevent hitting pistons during crankshaft rotation Move adjustable pushrod to exhaust lifter
Install rockers after obtaining zero lash using the appropriate shims required for correct wipe pattern
Rotate motor 340o (20o before end of exhaust stroke) pushing down on lifter to ensure valve closes and follows lobe of cam
Install dial indicator to measure movement of exhaust retainer
Rotate motor in 2o increments, measure PTV for each increment until 20o after piston passes top of stroke
Remove dial indicator and rockers
Measure adjustable pushrod overall length & gauge length
Install adjustable pushrod on intake valve
Rotate motor two turns stopping to 20o before piston is at top of overlap stroke
Install rockers and adjustable pushrod/verify zero lash
Install dial indicator on intake retainer
Rotate motor in 2o increments, measure PTV for each increment until 20o after piston passes top of stroke
Remove dial indicator and rockers
Remove adjustable pushrod
WARNING: Ensure lifter is down during crankshaft movement to prevent hitting pistons during crankshaft rotation Move adjustable pushrod to exhaust lifter
Install rockers after obtaining zero lash using the appropriate shims required for correct wipe pattern
Rotate motor 340o (20o before end of exhaust stroke) pushing down on lifter to ensure valve closes and follows lobe of cam
Install dial indicator to measure movement of exhaust retainer
Rotate motor in 2o increments, measure PTV for each increment until 20o after piston passes top of stroke
Remove dial indicator and rockers
Measure adjustable pushrod overall length & gauge length
Install adjustable pushrod on intake valve
Rotate motor two turns stopping to 20o before piston is at top of overlap stroke
Install rockers and adjustable pushrod/verify zero lash
Install dial indicator on intake retainer
Rotate motor in 2o increments, measure PTV for each increment until 20o after piston passes top of stroke
Remove dial indicator and rockers
Remove adjustable pushrod