Another Pushrod/Preload Question
Another Pushrod/Preload Question Ok first off, probably a dumb question but I'm curious, do I have to soak my lifters in oil before I install them and take a measurement for pushrods? Ok I have the Morel link-bar lifters and I used a stock pushrod (7.400) to measure for my new pushrods. After finding zero lash it took me 1 turn to torque to 22ft lbs. I know 1 turn equals .047 of preload. Do I add that to the pushrod length to get the new pushrods of 7.450? What is the correct size that I need?
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If one turn gives you ~0.047" pre-load with 7.400" pushrods, then you would want longer pushrods for more pre-load, and shorter pushrods for less pre-load.
For instance, if you wanted ~0.060" pre-load you'd want 7.415" pushrods. If you wanted ~0.070" pre-load, then you'd want 7.425" pushrods.
For instance, if you wanted ~0.060" pre-load you'd want 7.415" pushrods. If you wanted ~0.070" pre-load, then you'd want 7.425" pushrods.
Same here. You need to buy an adjustable pushrod and make an accurate measurement with these lifters since you have a 0.020" band to work with. I also spoke with someone at Morel before installing mine, he suggested putting the lifters in oil and rotating the wheel to break the grease up a bit before installing. I also coated the cam lobes with Redline Assembly Lube along with the pushrod tips and valve stem.
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Ok don't soak lifters, check. Alright I measured with the adjustable pushrod and I came up with 7.3125. I'm using a comp cams checker and it took 10 1/4 turns. So now that I've got that do I just add the desired preload to it?
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If you want 0.050" pre-load, then: 7.3125" + 0.050" = 7.363".
You can either buy pushrods as close as possible to the required lenght, or have some custom made.
Keep in mind that the Comp Cams pushrod checking tool measures in "gauge lenght".
Last edited by ZeeOSix; Feb 19, 2012 at 07:02 PM.
Ok first off, probably a dumb question but I'm curious, do I have to soak my lifters in oil before I install them and take a measurement for pushrods? Ok I have the Morel link-bar lifters and I used a stock pushrod (7.400) to measure for my new pushrods. After finding zero lash it took me 1 turn to torque to 22ft lbs. I know 1 turn equals .047 of preload. Do I add that to the pushrod length to get the new pushrods of 7.450? What is the correct size that I need?
As it only took 1 turn to torque you are going to have little less pre-load than you think as approx 1/3 of the final turn is what applies the locking torque to the bolt (it doesn't push the rocker/pushrod down farther).
As long as you were accurate in finding zero lash with this mock up you were close to perfect with the 7.4s.
If the checking tool turns out to be accurate and you are really seeing 7.3125 I'd purchase 7.350 length pushrods which should give you a pre-load of .037.
The other option is custom length, which will deliver quick from someone like Terry Manton at Manton Pushrods. You could also try Trend, I got custom length fully machined double taper pushrods within a week.
I don't mean to hijack, but since it seems the OP's questions have been answered and I don't want to clutter up the site, I'll ask here.
I have the Comp pushrod length checker and proceeded to measure Cyl. 1. It took 9.5 turns to get where I was comfortable with zero lash. The intake valve I couldn't really move at this length, but the exhaust valve would lift very little (without a tick, tick sound). So, at that many turns, I got 7.275" + what ever preload I choose. I think I want to shoot for 0.05".
I wanted to double check so I moved to Cyl. 6. On these two, I got 10.5 turns to zero lash. That game me a length of 7.325" + desired preload.
I had no real way of measuring TDC other than my eyeball, so I'm guessing that's why the pushrod measurements are equal lengths apart, in different directions? Am I correct in assuming that?
I know the Comp tool is measured in gauge length, so how would I equate that into my measurements?
Right now, It looks like I'll have to order some 7.350" pushrods with my 0.05" preload. I read that this is a great preload for a quiet valvetrain, but it doesn't seem to be well understood on the interwebz. I have a set of Texas-Speed 7.400 pushrods, but I'm afraid they will be too long.
I have the Comp pushrod length checker and proceeded to measure Cyl. 1. It took 9.5 turns to get where I was comfortable with zero lash. The intake valve I couldn't really move at this length, but the exhaust valve would lift very little (without a tick, tick sound). So, at that many turns, I got 7.275" + what ever preload I choose. I think I want to shoot for 0.05".
I wanted to double check so I moved to Cyl. 6. On these two, I got 10.5 turns to zero lash. That game me a length of 7.325" + desired preload.
I had no real way of measuring TDC other than my eyeball, so I'm guessing that's why the pushrod measurements are equal lengths apart, in different directions? Am I correct in assuming that?
I know the Comp tool is measured in gauge length, so how would I equate that into my measurements?
Right now, It looks like I'll have to order some 7.350" pushrods with my 0.05" preload. I read that this is a great preload for a quiet valvetrain, but it doesn't seem to be well understood on the interwebz. I have a set of Texas-Speed 7.400 pushrods, but I'm afraid they will be too long.
Ok measured #6 and got 7.3125" just like #1. Does the gauge length mean I need to add anything to my total length? If not it looks like I could run 7.350" and have aprox. .040" of preload.
I don't mean to hijack, but since it seems the OP's questions have been answered and I don't want to clutter up the site, I'll ask here.
I have the Comp pushrod length checker and proceeded to measure Cyl. 1. It took 9.5 turns to get where I was comfortable with zero lash. The intake valve I couldn't really move at this length, but the exhaust valve would lift very little (without a tick, tick sound). So, at that many turns, I got 7.275" + what ever preload I choose. I think I want to shoot for 0.05".
I wanted to double check so I moved to Cyl. 6. On these two, I got 10.5 turns to zero lash. That game me a length of 7.325" + desired preload.
I had no real way of measuring TDC other than my eyeball, so I'm guessing that's why the pushrod measurements are equal lengths apart, in different directions? Am I correct in assuming that?
I know the Comp tool is measured in gauge length, so how would I equate that into my measurements?
Right now, It looks like I'll have to order some 7.350" pushrods with my 0.05" preload. I read that this is a great preload for a quiet valvetrain, but it doesn't seem to be well understood on the interwebz. I have a set of Texas-Speed 7.400 pushrods, but I'm afraid they will be too long.
I have the Comp pushrod length checker and proceeded to measure Cyl. 1. It took 9.5 turns to get where I was comfortable with zero lash. The intake valve I couldn't really move at this length, but the exhaust valve would lift very little (without a tick, tick sound). So, at that many turns, I got 7.275" + what ever preload I choose. I think I want to shoot for 0.05".
I wanted to double check so I moved to Cyl. 6. On these two, I got 10.5 turns to zero lash. That game me a length of 7.325" + desired preload.
I had no real way of measuring TDC other than my eyeball, so I'm guessing that's why the pushrod measurements are equal lengths apart, in different directions? Am I correct in assuming that?
I know the Comp tool is measured in gauge length, so how would I equate that into my measurements?
Right now, It looks like I'll have to order some 7.350" pushrods with my 0.05" preload. I read that this is a great preload for a quiet valvetrain, but it doesn't seem to be well understood on the interwebz. I have a set of Texas-Speed 7.400 pushrods, but I'm afraid they will be too long.
By counting turns you are actually measuring to gauge length. This is the length your order for most pushrods. Trend uses this measurement and as a result so does Comp since Trend makes their pushrods. Manton on the other hand uses overall length and you need a caliper to measure your adjustable pushrod to get this measurement. Hope this make sense.
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By counting turns you are actually measuring to gauge length. This is the length your order for most pushrods. Trend uses this measurement and as a result so does Comp since Trend makes their pushrods. Manton on the other hand uses overall length and you need a caliper to measure your adjustable pushrod to get this measurement. Hope this make sense.
Another way to get the "flat-to-flat" length from the gauge length measurement is to add 0.015" to the gauge length. See attachment in Post #9.
For instance, 7.385" gauge length would equal 7.400" flat-to-flat length.
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My first thought was "damn he's close with stock length pushrods".
As it only took 1 turn to torque you are going to have little less pre-load than you think as approx 1/3 of the final turn is what applies the locking torque to the bolt (it doesn't push the rocker/pushrod down farther).
As it only took 1 turn to torque you are going to have little less pre-load than you think as approx 1/3 of the final turn is what applies the locking torque to the bolt (it doesn't push the rocker/pushrod down farther).
Thanks for all the info and help everybody. So I got 7.3125" measured + 0.050" preload + 0.015" gauge length = 7.3775" Looks like I should go with a 7.375" pushrod and should be just fine.
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If you use pushrods specified by the gauge length, then you would need 7.3125 + 0.050 = 7.3625 since you used the Comp Cams length checking tool, which gives you a gauge length measurement.
If you use pushrods specified by the flat-to-flat lenght, then you would need pushrods that were 7.3775 from flat-to-flat as you showed above.