Need help using Pushrod Length Checker....
10-02-2006, 01:52 PM
#1
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Need help using Pushrod Length Checker.... I've done some research on past threads about determining correct pushrod length, but I need a little more insight. I'm somewhat mechanical, but a little new to LS1 engines. Anyway, I will list a few of the questions I have, and if anyone could help or point me in the right direction about the WHOLE process, I'd really appreciate it.
1. What amount of preload should I use with my stock lifters?
2. How do I turn the engine over when the pushrod length checker is in the engine. (I'm using the compcams checker)
3. How concerned do I need to be with where the rocker is contacting the valve tip?
4. Is there any specific order to tightening down the rockers when I'm done?
5. When I have the pushrod checker installed, do I torque down the rocker to 22 foot pounds to get the accurate measurment?
6. I'm a little confused about valve lash. What does "ZERO" lash mean? What do I need to look for in terms of lash when I am trying to find the correct length?
I'm just a weekend warrior trying to learn about my engine, and save some labor charges from the mechanic. I don't pretend to know more than I really do. Any help would be appreciated. Thanks.
Shaun
1. What amount of preload should I use with my stock lifters?
2. How do I turn the engine over when the pushrod length checker is in the engine. (I'm using the compcams checker)
3. How concerned do I need to be with where the rocker is contacting the valve tip?
4. Is there any specific order to tightening down the rockers when I'm done?
5. When I have the pushrod checker installed, do I torque down the rocker to 22 foot pounds to get the accurate measurment?
6. I'm a little confused about valve lash. What does "ZERO" lash mean? What do I need to look for in terms of lash when I am trying to find the correct length?
I'm just a weekend warrior trying to learn about my engine, and save some labor charges from the mechanic. I don't pretend to know more than I really do. Any help would be appreciated. Thanks.
Shaun
10-02-2006, 03:23 PM
#2
1. 0.080" - 0.100"
2. You don't need to turn it over, get the #1 cylinder at top dead center so both lifters are on the base circle.
3. Not sure I understand, are you referring to the wipe pattern?
4. Yes, it is specified in the service manual starting with the engine at top dead center.
5. You don't need to go to 22 lb-ft, 10 lb-ft is more than enought. You only need to seat the rocker, not fully preload the bolt. Make sure the pushrod is loose and then extend it once the rocker is tightened. You will need to mark it and then count turns using the two white lines as a guide. Each time the white lines pass each other (one turn) it is 0.050" longer than the base length of the adjustable pushrod.
6. Zero lash will be when you screw out the adjustable pushrod with the rocker tightened in place such that full contact is made and you can't get any "tick" "tick" when you try to lift the end of the rocker that contacts the valve stem. If you then back off a little on the pushrod the "tick" "tick" will return if you lift the rocker, you will get the feel of it. Once you eliminate this you are are zero lash. Don't move the rocker side to side, only up and down to gauge when you have zero lash.
2. You don't need to turn it over, get the #1 cylinder at top dead center so both lifters are on the base circle.
3. Not sure I understand, are you referring to the wipe pattern?
4. Yes, it is specified in the service manual starting with the engine at top dead center.
5. You don't need to go to 22 lb-ft, 10 lb-ft is more than enought. You only need to seat the rocker, not fully preload the bolt. Make sure the pushrod is loose and then extend it once the rocker is tightened. You will need to mark it and then count turns using the two white lines as a guide. Each time the white lines pass each other (one turn) it is 0.050" longer than the base length of the adjustable pushrod.
6. Zero lash will be when you screw out the adjustable pushrod with the rocker tightened in place such that full contact is made and you can't get any "tick" "tick" when you try to lift the end of the rocker that contacts the valve stem. If you then back off a little on the pushrod the "tick" "tick" will return if you lift the rocker, you will get the feel of it. Once you eliminate this you are are zero lash. Don't move the rocker side to side, only up and down to gauge when you have zero lash.
10-02-2006, 04:50 PM
#3
TECH Addict
Like vettnuts says:
80 to 100
Bring the cylinder to be checked into position then install the checker, don't turn it over with the checker in place.
Check a couple of cylinders - that way you get a better overall reading. Some check all, but it's generally not necessary.
It's a good idea to check the geometry of where the rocker contacts the tip, for most applications as long as you're near the center with the correct length pushrod you'll be OK.
Ideally you want to tighten them when the valves are colsed but many folks just tighten them all down with very few problems.
Tighten the rocker down solid, don't worry about 22 ft lbs, when you no longer have play in the rocker to checker clearnce or when you can no longer turn the tip of the checker you are at 0 lash. A good tip is to put a rubber band around the lower part of the checker to hold it place so you can turn just the top. Count the number of turns from the base, multiply by .050 and add it to the 6.800 of the checker. Then add you preload and you have your pushrod length. Put sealer on the threads of the rocker bolts for final assembly and you're done.
80 to 100
Bring the cylinder to be checked into position then install the checker, don't turn it over with the checker in place.
Check a couple of cylinders - that way you get a better overall reading. Some check all, but it's generally not necessary.
It's a good idea to check the geometry of where the rocker contacts the tip, for most applications as long as you're near the center with the correct length pushrod you'll be OK.
Ideally you want to tighten them when the valves are colsed but many folks just tighten them all down with very few problems.
Tighten the rocker down solid, don't worry about 22 ft lbs, when you no longer have play in the rocker to checker clearnce or when you can no longer turn the tip of the checker you are at 0 lash. A good tip is to put a rubber band around the lower part of the checker to hold it place so you can turn just the top. Count the number of turns from the base, multiply by .050 and add it to the 6.800 of the checker. Then add you preload and you have your pushrod length. Put sealer on the threads of the rocker bolts for final assembly and you're done.
08-19-2008, 09:53 PM
#6
1. 0.080" - 0.100"
2. You don't need to turn it over, get the #1 cylinder at top dead center so both lifters are on the base circle.
3. Not sure I understand, are you referring to the wipe pattern?
4. Yes, it is specified in the service manual starting with the engine at top dead center.
5. You don't need to go to 22 lb-ft, 10 lb-ft is more than enought. You only need to seat the rocker, not fully preload the bolt. Make sure the pushrod is loose and then extend it once the rocker is tightened. You will need to mark it and then count turns using the two white lines as a guide. Each time the white lines pass each other (one turn) it is 0.050" longer than the base length of the adjustable pushrod.
6. Zero lash will be when you screw out the adjustable pushrod with the rocker tightened in place such that full contact is made and you can't get any "tick" "tick" when you try to lift the end of the rocker that contacts the valve stem. If you then back off a little on the pushrod the "tick" "tick" will return if you lift the rocker, you will get the feel of it. Once you eliminate this you are are zero lash. Don't move the rocker side to side, only up and down to gauge when you have zero lash.
2. You don't need to turn it over, get the #1 cylinder at top dead center so both lifters are on the base circle.
3. Not sure I understand, are you referring to the wipe pattern?
4. Yes, it is specified in the service manual starting with the engine at top dead center.
5. You don't need to go to 22 lb-ft, 10 lb-ft is more than enought. You only need to seat the rocker, not fully preload the bolt. Make sure the pushrod is loose and then extend it once the rocker is tightened. You will need to mark it and then count turns using the two white lines as a guide. Each time the white lines pass each other (one turn) it is 0.050" longer than the base length of the adjustable pushrod.
6. Zero lash will be when you screw out the adjustable pushrod with the rocker tightened in place such that full contact is made and you can't get any "tick" "tick" when you try to lift the end of the rocker that contacts the valve stem. If you then back off a little on the pushrod the "tick" "tick" will return if you lift the rocker, you will get the feel of it. Once you eliminate this you are are zero lash. Don't move the rocker side to side, only up and down to gauge when you have zero lash.
vettenuts I have always found your info dead on accurate and I just want you to to know you have some of the the most useful posts on this site. I hope you hang here for a long time
08-19-2008, 10:27 PM
#7
I agree about vettenuts knowledge and willingness to share. Thanks!
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
DaddySS, what do you mean by using a rubber band on the bottom part of the checker? Pic?
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
DaddySS, what do you mean by using a rubber band on the bottom part of the checker? Pic?
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08-20-2008, 01:36 PM
#8
I agree about vettenuts knowledge and willingness to share. Thanks!
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
08-20-2008, 11:27 PM
#9
I agree about vettenuts knowledge and willingness to share. Thanks!
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
DaddySS, what do you mean by using a rubber band on the bottom part of the checker? Pic?
The hardest part I found with using the checker on LS1 engines is getting my fat fingers in there to turn the darn thing. The heads are tall where the valve cover sits on these engines compared to a SBC and don't give much room to work with.
DaddySS, what do you mean by using a rubber band on the bottom part of the checker? Pic?
The lower part of the adj PR also spins when you turn the top part. One can not hold it with their hand, so the rubber band is positioned on the lower part of the pushrod checker such that it "holds on" against the hole in the head, preventing it from spinning.
I hope that makes sense. I'm in full kick back mode here.
Last edited by ShevrolayZ28; 08-20-2008 at 11:33 PM.
