Pushrod Measuring Method ?s...
01-28-2011, 09:17 AM
#1
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Pushrod Measuring Method ?s... I know, there are other ways to measure length, but for several reasons I am considering this method, was posted here back in '08 but I only found this one post about it, which makes me wonder since it seems a lot more simpler especially for those of us w/o solid lifters, checker springs etc. So I'm concerned there is a reason why I SHOULDN'T do this, is there?
The method is assuming you are already on base circle.
Simply, is this method sound?
The method is assuming you are already on base circle.
You would remove two rockers(1 intake, 1 exhaust). Adjust your pushrod length tool to about 7.350(maybe more maybe less depending on your setup). Reinstall the rocker and tighten to 22 ft.lbs. Loosen the pushrod tool until it contacts the rocker and the rocker has no play between the valve tip and pushrod(zero lash). Remove the tool without turning it and measure it with a caliper or count the turns(each is equal to .050) and add the length of the tool(about 6.8").
Take the length of the tool + the amount of turns + .080(preload) and that is your pushrod length.
Example: 6.8" + .5"(10 turns) + .080 = 7.380...this is from my motor in which I used a 7.375" pushrod.
Hope this helps.
Take the length of the tool + the amount of turns + .080(preload) and that is your pushrod length.
Example: 6.8" + .5"(10 turns) + .080 = 7.380...this is from my motor in which I used a 7.375" pushrod.
Hope this helps.
01-28-2011, 10:55 PM
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Well, I measured and came up with ~7.35 (there was a very small smidgen of wiggle but the allowed preload variation should compensate, tested w/ .025 more and was way tight), which coincides with the simple math I did (smaller base circle - ls7 lifters need shorter rod - thinner gasket = ~.040 less than stock).
I would recommend this method to the majority of us out there with OEM lifters to check their valvetrain, though with a small change:
Instead of trying to wiggle your finger in there to extend the length checker, use a piece of tape and "set" it to what you think is right, get the rocker to ratchet "snug" then if there's noticeable (more than a mm) of lash, then untighten the rocker and extend the checker appropriately. Once you are less than a mm go ahead and torque to spec and during this constantly check for lash, it should be perfect at this point, but keep checking to make sure you do not depress the lifter. This will prevent second guessing if the tool decides to loosen or tighten on its own while you're taking it off to check.
I would recommend this method to the majority of us out there with OEM lifters to check their valvetrain, though with a small change:
Instead of trying to wiggle your finger in there to extend the length checker, use a piece of tape and "set" it to what you think is right, get the rocker to ratchet "snug" then if there's noticeable (more than a mm) of lash, then untighten the rocker and extend the checker appropriately. Once you are less than a mm go ahead and torque to spec and during this constantly check for lash, it should be perfect at this point, but keep checking to make sure you do not depress the lifter. This will prevent second guessing if the tool decides to loosen or tighten on its own while you're taking it off to check.
02-28-2011, 03:24 PM
#6
Yes, the lifter needs to be on the base circle. TDC would be best, because you can check both the intake and exhaust without changing anything. Also I would do this after running the motor to make sure the lifter is pumped up.
