how is pushrod length checker useful without dial indicator?
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how is pushrod length checker useful without dial indicator? I don't see how an adjustable pushrod is useful without a dial indicator. The only way I see how this could be useful is if you are planning on torquing the bolts down to 22 ft-lbs and it takes 1-1.25 rotations of the wrench. I have no idea how much preload this would be but I see this being a common guess when using the LS7 lifters.
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Many adjustable pushrod length checkers have hash marks denoting the length in .050" increments. The Comp Cams one I use is 6.800" when tightened all the way down, and you adjust it to where there is no vertical slack in the valvetrain on the basecircle of the cam to read its measurement. If it shows 10 hash mark lines (10 x .050 = .500") then the length with no preload is 7.300", add your preload to that (say .050" preload) and this number is your desired pushrod length - 7.350"
You can use a dial indicator with a non-adjustable known length pushrod as well in the same manner. The difference being you need a pushrod pretty close to what is needed. I often do this with oddbad combinations that require pushrods in the 8.0-8.2 range.
You can use a dial indicator with a non-adjustable known length pushrod as well in the same manner. The difference being you need a pushrod pretty close to what is needed. I often do this with oddbad combinations that require pushrods in the 8.0-8.2 range.
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Okay, so I should put in the adjustable pushrod with it screwed all the way in (shortest position) and then tighten the bolt to 22ft-lbs. Then I can adjust the pushrod so there is no slack. Once this is done then I add the desired preload by counting hashmarks on the adjustable pushrod. Finally, measure the pushrod and this is the length that I should get. Are all of these steps correct?
0.040 X 2.7/1.7 is the correct way. You have to account for rocker ratio. However, this is from zero lash until the rocker seats, you can't count for the tightening of the bolt beyond rocker seating as the rocker is not moving.
Okay, so I should put in the adjustable pushrod with it screwed all the way in (shortest position) and then tighten the bolt to 22ft-lbs. Then I can adjust the pushrod so there is no slack. Once this is done then I add the desired preload by counting hashmarks on the adjustable pushrod. Finally, measure the pushrod and this is the length that I should get. Are all of these steps correct?
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Why do you not need to torque the bolt down, but only snug it when you are checking for the length? I would think torquing it would change the overall length.
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The change from hand tight/snug to full torque is not very much a few thousandths. Torqueing them would get the measurement more precise if you want to get your preload to the thousandth. Most of the time preload is fine if it falls within a certain range ,not as critical as lets say bearing clearances etc.
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Also, my heads are setup for 3/8" pushrods. I believe the adjustable pushrod I have is a comp one. I think these are 5/16." Do I need to get a 3/8" adjustable pushrod to check for preload? Or I know comp makes 3/8" pushrods with a 5/16" ends. Thanks for the suggestions.
Two things happen when you tighten the bolt. First, you draw the rocker down until it contacts the support and can't move any more. At this point, further tightening preloads the bolt. With aluminum threads, it is best not to keep loading to full torque multiple times as you go through the procedure to figure out the length of the pushrod. In this case, the change in measurement is small if at all.
Here is how to use the adjustable pushrod. Link
If you're just using your fingers to lengthen the pushrod checker and keep checking length as you extend it, you shouldn't compress your lifter. If you start with the checker extended too far, then you could compress a lifter which is why you should start with it short and turn to extend.
