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Pushrod checking tool length concern

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Old 02-09-2013, 11:13 AM
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Default Pushrod checking tool length concern

Hello all,

I bought a comp pushrod checker and I have got a digital caliber to make things more accurate. Now, what made me concerned was when I checked the comp pushrod I got 0.020" more than 6.800 fully closed.

The question is, do I go with comp measure of dead 6.800 or do I add the difference to the final measure. It makes a huge difference in the final lifter preload.

Thanks
Old 02-09-2013, 01:05 PM
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Originally Posted by muayyadf1
Hello all,

I bought a comp pushrod checker and I have got a digital caliber to make things more accurate. Now, what made me concerned was when I checked the comp pushrod I got 0.020" more than 6.800 fully closed.

The question is, do I go with comp measure of dead 6.800 or do I add the difference to the final measure. It makes a huge difference in the final lifter preload.
Start with it at 7.400" length then add or subtract length as needed to determin the length needed, at exaxctly half your valve lift, your roller tip should be dead center of the valve tip, not past center, not before center, you'll need a dial indicator set up as well to find middle of of total valve lift. There are sites/youtubes? that have illistrations for better understanding.
Thanks
Old 02-09-2013, 01:11 PM
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Originally Posted by muayyadf1
Hello all,

I bought a comp pushrod checker and I have got a digital caliber to make things more accurate. Now, what made me concerned was when I checked the comp pushrod I got 0.020" more than 6.800 fully closed.

The question is, do I go with comp measure of dead 6.800 or do I add the difference to the final measure. It makes a huge difference in the final lifter preload.

Thanks
The sole purpose of the comp cam tool is to NOT use a caliper!

The Comp Cam tool is a measuring device to measure for push rods in gauge length, NOT tip to tip.

Ditch the calipers, measure with the tool per the instructions.

Zero turns is 6.8" gauge length, and add from there. You don't need to be exact or else you will be buying custom length PRs for each valve.
Old 02-09-2013, 01:37 PM
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Thanks,

I won't use the caliber then with this type of pushrod checker.
I guess that I need to use a caliber with the other type of checkers which have two bolts on the screw with no dot marks.
Old 02-11-2013, 04:32 AM
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The adjustable pushrod measures gauge length, which is a location on the ball where the diameter is 0.140". That would be a hard location to find with a caliper. You are measuring overall length, which is the distance between the flats formed by the hole in the end of the ball.

The difference you have found (0.020") is a reasonable value for the difference between gauge length and overall length. You can measure with the caliper as long as you understand the difference. Many companys sell pushrods in gauge length (Trend makes many of the pushrods out there including Comp and they use gauge length). However, some companies do use overall length such as Manton.

It is important that you understand the difference as you could end up ordering the next size pushrod if not careful, but your measurement is correct.
Old 02-11-2013, 05:55 AM
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http://www.compcams.com/Products/CC-...rods%27-0.aspx
Old 02-11-2013, 04:25 PM
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don't use calipers to measure pushrods, it doesn't work that way. Ensure your pushrod checker is not damaged or out of spec. Ensure you have the correct pushrod checker (fully closed should be 6.800"). If all that checks out then trust your tools.
Old 02-11-2013, 04:36 PM
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Cheap digital calipers suck for fine measurements. They are wrong.



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