Ok so I'd rather be safe then sorry. Please Look!
06-25-2009, 06:22 PM
#1
ISIS SUCKS FAT CHOAD
Thread Starter
Ok so I'd rather be safe then sorry. Please Look!
Ok so I'm doing a head and cam swap. I already have my heads cam and smith brothers pushrods. (some of the other new components are Timing chain, Oil Pump and Lifters) With all of this lifeter talk going around, I decided to just check for proper push rod length rather then stick the push rods I ordered in my engine and have trouble later. What I woulld like to know is what push rod length checker should I order. I see comp cams has a master push rod checking kit. I want this to be as painless as possible and as accurate as possible. Any help you guy's throw my way would be appreciated.
06-25-2009, 07:07 PM
#2
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St. Jude Donor '03
Comp part # 7702 is their adjustable pushrod measuring tool for between 6.800 and 7.800". You can easily find it for about $20.
Once you measure and find the zero-lash length, add your desired preload distance to that measured value, and that will be the length pushrod you want to order.
Now also note, pushrod manufacturers sometimes measure them differently. The Comp will tell you gauge length. Some specialty pushrod manufacturers deal with overall length, and will request you measure that with a caliper or mic.
Overall length is typically .017" longer than gauge length, but the only point of me saying this is not to confuse you, but to be sure you're comparing apples to apples when ordering from your specific supplier. (I don't know how Smith Bros quantifies length compared to others).
When you get to that point, and have any questions about the process or measurement found...ask away....either here, or with your pushrod supplier.
Once you measure and find the zero-lash length, add your desired preload distance to that measured value, and that will be the length pushrod you want to order.
Now also note, pushrod manufacturers sometimes measure them differently. The Comp will tell you gauge length. Some specialty pushrod manufacturers deal with overall length, and will request you measure that with a caliper or mic.
Overall length is typically .017" longer than gauge length, but the only point of me saying this is not to confuse you, but to be sure you're comparing apples to apples when ordering from your specific supplier. (I don't know how Smith Bros quantifies length compared to others).
When you get to that point, and have any questions about the process or measurement found...ask away....either here, or with your pushrod supplier.
06-25-2009, 07:19 PM
#3
ISIS SUCKS FAT CHOAD
Thread Starter
Comp part # 7702 is their adjustable pushrod measuring tool for between 6.800 and 7.800". You can easily find it for about $20.
Once you measure and find the zero-lash length, add your desired preload distance to that measured value, and that will be the length pushrod you want to order.
Now also note, pushrod manufacturers sometimes measure them differently. The Comp will tell you gauge length. Some specialty pushrod manufacturers deal with overall length, and will request you measure that with a caliper or mic.
Overall length is typically .017" longer than gauge length, but the only point of me saying this is not to confuse you, but to be sure you're comparing apples to apples when ordering from your specific supplier. (I don't know how Smith Bros quantifies length compared to others).
When you get to that point, and have any questions about the process or measurement found...ask away....either here, or with your pushrod supplier.
Once you measure and find the zero-lash length, add your desired preload distance to that measured value, and that will be the length pushrod you want to order.
Now also note, pushrod manufacturers sometimes measure them differently. The Comp will tell you gauge length. Some specialty pushrod manufacturers deal with overall length, and will request you measure that with a caliper or mic.
Overall length is typically .017" longer than gauge length, but the only point of me saying this is not to confuse you, but to be sure you're comparing apples to apples when ordering from your specific supplier. (I don't know how Smith Bros quantifies length compared to others).
When you get to that point, and have any questions about the process or measurement found...ask away....either here, or with your pushrod supplier.
Thanks Tom.
08-22-2009, 02:05 PM
#4
ISIS SUCKS FAT CHOAD
Thread Starter
hey to anyone taht can answer. I got my comp pushrod length checker tool in today. they were on back order forever. anyway, is there a final answer on what the preload on the LS1 lifters which are apparently the replacement lifters for the LS1 engine now. also how do you find zero lash on these engines?
I actually have two pushrod length checkers so if someone wants to buy one from me 20 bucks shipped in the main land united stated.
I actually have two pushrod length checkers so if someone wants to buy one from me 20 bucks shipped in the main land united stated.
Last edited by MVP'S ZO6; 08-22-2009 at 02:22 PM.
08-22-2009, 10:32 PM
#6
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St. Jude Donor '03
Bolt up a rocker arm and a stock pushrod (any cyl - doesn't matter), and spin the engine until you see that valve is fully closed...spin the engine a bit more just to be sure there is no more valve movement. This means you are on the base circle of the cam.
Unbolt the rocker, remove pushrod. Adjust your adjustable pushrod to be close to your stock one. Insert it, and tighten up the rocker arm again.
If you cannot wiggle the rocker arm to the pushrod after doing so, remove the adj. pushrod, and tighten (shorten) it a turn or two, and reinstall rocker arm.
When you get the pushrod short enough that the rocker is loose, and rocks up/down to the pushrod (it makes a nice clicking sound), what you want to do is unscrew (lengthen) the pushrod until any wiggle/freeplay in the rocker is taken up.
The complication here, is that the entire pushrod may tend to turn instead of unscrewing the two pieces while trying to adjust it in place. There's just enough room under the rocker to get fingers in there and spin the pushrod, and it's kind of impossible to hold one half, while just spinning the other. You may have to remove the rocker, adjust, reinstall rocker until you find that magic point where there is no slop between the two (rocker and pushrod), yet not compressing the lifter in the process. This point is what's known as zero-lash.
Once you get there (and believe me, it takes a while on the first try), remove your adjustable pushrod, note the location of the match-marks on it, and screw the two halves down until the marks meet. 1/4, 1/2, 3/4 turn, etc. Once the match marks line up, continue to tighten the pushrod until fully closed, counting each full turn as you go.
The collapsed length of the adjustable pushrod is 6.800". Each full turn equals .050". If it took 9.5 full turns to fully collapse from your zero-lash measurement point, that would be .475".
6.800" +.475" = 7.275" (for example).
If you're still understanding, now is the time to add in your desired lifter preload to your measured pushrod length On a stock LS1/7 lifter, .060-.080" is what most shoot for.
If you really did measure 7.275", and add preload...if buying a shelf pushrod like a Comp (which are sold in .025" increments), you'd probably be good with a 7.350" length, which would provide .075" lifter preload.
If buying a more custom pushrod like from Manton or Smith Bros...they may ask you measure (mic/vernier) the overall length of the adjustable pushrod, which is a slightly different value than the gauge length the adjustable pushrod tells you.
Depending on your cam (specially if it's one using miixed lobe profiles), you may wish to measure and check both an intake and exhaust valve, as they may very well be different. But with stock lifters, there is enough preload range and "forgivenesss", you probably can get away with all 16 pushods the same length.
Hope that helps.
Unbolt the rocker, remove pushrod. Adjust your adjustable pushrod to be close to your stock one. Insert it, and tighten up the rocker arm again.
If you cannot wiggle the rocker arm to the pushrod after doing so, remove the adj. pushrod, and tighten (shorten) it a turn or two, and reinstall rocker arm.
When you get the pushrod short enough that the rocker is loose, and rocks up/down to the pushrod (it makes a nice clicking sound), what you want to do is unscrew (lengthen) the pushrod until any wiggle/freeplay in the rocker is taken up.
The complication here, is that the entire pushrod may tend to turn instead of unscrewing the two pieces while trying to adjust it in place. There's just enough room under the rocker to get fingers in there and spin the pushrod, and it's kind of impossible to hold one half, while just spinning the other. You may have to remove the rocker, adjust, reinstall rocker until you find that magic point where there is no slop between the two (rocker and pushrod), yet not compressing the lifter in the process. This point is what's known as zero-lash.
Once you get there (and believe me, it takes a while on the first try), remove your adjustable pushrod, note the location of the match-marks on it, and screw the two halves down until the marks meet. 1/4, 1/2, 3/4 turn, etc. Once the match marks line up, continue to tighten the pushrod until fully closed, counting each full turn as you go.
The collapsed length of the adjustable pushrod is 6.800". Each full turn equals .050". If it took 9.5 full turns to fully collapse from your zero-lash measurement point, that would be .475".
6.800" +.475" = 7.275" (for example).
If you're still understanding, now is the time to add in your desired lifter preload to your measured pushrod length On a stock LS1/7 lifter, .060-.080" is what most shoot for.
If you really did measure 7.275", and add preload...if buying a shelf pushrod like a Comp (which are sold in .025" increments), you'd probably be good with a 7.350" length, which would provide .075" lifter preload.
If buying a more custom pushrod like from Manton or Smith Bros...they may ask you measure (mic/vernier) the overall length of the adjustable pushrod, which is a slightly different value than the gauge length the adjustable pushrod tells you.
Depending on your cam (specially if it's one using miixed lobe profiles), you may wish to measure and check both an intake and exhaust valve, as they may very well be different. But with stock lifters, there is enough preload range and "forgivenesss", you probably can get away with all 16 pushods the same length.
Hope that helps.
08-22-2009, 10:55 PM
#7
ISIS SUCKS FAT CHOAD
Thread Starter
Bolt up a rocker arm and a stock pushrod (any cyl - doesn't matter), and spin the engine until you see that valve is fully closed...spin the engine a bit more just to be sure there is no more valve movement. This means you are on the base circle of the cam.
Unbolt the rocker, remove pushrod. Adjust your adjustable pushrod to be close to your stock one. Insert it, and tighten up the rocker arm again.
If you cannot wiggle the rocker arm to the pushrod after doing so, remove the adj. pushrod, and tighten (shorten) it a turn or two, and reinstall rocker arm.
When you get the pushrod short enough that the rocker is loose, and rocks up/down to the pushrod (it makes a nice clicking sound), what you want to do is unscrew (lengthen) the pushrod until any wiggle/freeplay in the rocker is taken up.
The complication here, is that the entire pushrod may tend to turn instead of unscrewing the two pieces while trying to adjust it in place. There's just enough room under the rocker to get fingers in there and spin the pushrod, and it's kind of impossible to hold one half, while just spinning the other. You may have to remove the rocker, adjust, reinstall rocker until you find that magic point where there is no slop between the two (rocker and pushrod), yet not compressing the lifter in the process. This point is what's known as zero-lash.
Once you get there (and believe me, it takes a while on the first try), remove your adjustable pushrod, note the location of the match-marks on it, and screw the two halves down until the marks meet. 1/4, 1/2, 3/4 turn, etc. Once the match marks line up, continue to tighten the pushrod until fully closed, counting each full turn as you go.
The collapsed length of the adjustable pushrod is 6.800". Each full turn equals .050". If it took 9.5 full turns to fully collapse from your zero-lash measurement point, that would be .475".
6.800" +.475" = 7.275" (for example).
If you're still understanding, now is the time to add in your desired lifter preload to your measured pushrod length On a stock LS1/7 lifter, .060-.080" is what most shoot for.
If you really did measure 7.275", and add preload...if buying a shelf pushrod like a Comp (which are sold in .025" increments), you'd probably be good with a 7.350" length, which would provide .075" lifter preload.
If buying a more custom pushrod like from Manton or Smith Bros...they may ask you measure (mic/vernier) the overall length of the adjustable pushrod, which is a slightly different value than the gauge length the adjustable pushrod tells you.
Depending on your cam (specially if it's one using miixed lobe profiles), you may wish to measure and check both an intake and exhaust valve, as they may very well be different. But with stock lifters, there is enough preload range and "forgivenesss", you probably can get away with all 16 pushods the same length.
Hope that helps.
Unbolt the rocker, remove pushrod. Adjust your adjustable pushrod to be close to your stock one. Insert it, and tighten up the rocker arm again.
If you cannot wiggle the rocker arm to the pushrod after doing so, remove the adj. pushrod, and tighten (shorten) it a turn or two, and reinstall rocker arm.
When you get the pushrod short enough that the rocker is loose, and rocks up/down to the pushrod (it makes a nice clicking sound), what you want to do is unscrew (lengthen) the pushrod until any wiggle/freeplay in the rocker is taken up.
The complication here, is that the entire pushrod may tend to turn instead of unscrewing the two pieces while trying to adjust it in place. There's just enough room under the rocker to get fingers in there and spin the pushrod, and it's kind of impossible to hold one half, while just spinning the other. You may have to remove the rocker, adjust, reinstall rocker until you find that magic point where there is no slop between the two (rocker and pushrod), yet not compressing the lifter in the process. This point is what's known as zero-lash.
Once you get there (and believe me, it takes a while on the first try), remove your adjustable pushrod, note the location of the match-marks on it, and screw the two halves down until the marks meet. 1/4, 1/2, 3/4 turn, etc. Once the match marks line up, continue to tighten the pushrod until fully closed, counting each full turn as you go.
The collapsed length of the adjustable pushrod is 6.800". Each full turn equals .050". If it took 9.5 full turns to fully collapse from your zero-lash measurement point, that would be .475".
6.800" +.475" = 7.275" (for example).
If you're still understanding, now is the time to add in your desired lifter preload to your measured pushrod length On a stock LS1/7 lifter, .060-.080" is what most shoot for.
If you really did measure 7.275", and add preload...if buying a shelf pushrod like a Comp (which are sold in .025" increments), you'd probably be good with a 7.350" length, which would provide .075" lifter preload.
If buying a more custom pushrod like from Manton or Smith Bros...they may ask you measure (mic/vernier) the overall length of the adjustable pushrod, which is a slightly different value than the gauge length the adjustable pushrod tells you.
Depending on your cam (specially if it's one using miixed lobe profiles), you may wish to measure and check both an intake and exhaust valve, as they may very well be different. But with stock lifters, there is enough preload range and "forgivenesss", you probably can get away with all 16 pushods the same length.
Hope that helps.
Awesome! Tom your always such a great help. I have a couple more questions. (1) Once I determine my correct pushrod length do I need to take into account the thickness of my head gasket and the fact that my stock LS1 heads (casting # 806) have been milled.025"?
Also I ordered a set of the commetic head gaskits as you recommended to be in the past. However I sent them back because after compairing them to the stock MLS gasket they are virtually identical which leads me to believe that the stock MLS gaskets will not leak with my notched cylinder heads. I believe they are a revised version of the first set of MLS gaskets GM developed for the LSx engine.
Last edited by MVP'S ZO6; 08-22-2009 at 10:58 PM.
08-22-2009, 11:15 PM
#8
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St. Jude Donor '03
The point of measuring for correct pushrod length is BECAUSE of all those assembly variances...head milling, gasket thickness, etc.
All of that should be already be assembled. Heads on and torqued. The resulting distance between lifter and rocker arm is what it is....the measuring tool tells you what the pushrod needs to be to fit that distance.
All of that should be already be assembled. Heads on and torqued. The resulting distance between lifter and rocker arm is what it is....the measuring tool tells you what the pushrod needs to be to fit that distance.
08-23-2009, 12:13 AM
#9
ISIS SUCKS FAT CHOAD
Thread Starter
The point of measuring for correct pushrod length is BECAUSE of all those assembly variances...head milling, gasket thickness, etc.
All of that should be already be assembled. Heads on and torqued. The resulting distance between lifter and rocker arm is what it is....the measuring tool tells you what the pushrod needs to be to fit that distance.
All of that should be already be assembled. Heads on and torqued. The resulting distance between lifter and rocker arm is what it is....the measuring tool tells you what the pushrod needs to be to fit that distance.
08-23-2009, 05:58 AM
#10
ISIS SUCKS FAT CHOAD
Thread Starter
Ok, I went out to the garage and followed the procedure Tom posted and it worked like a charm. The push rod length I need is 7.370 i checked it severl times all with the same results. I even checked the exhaust side and got the same results. now that ive done the procedure its real easy to do. thanks Tom. I have a set of smith bros. pushrods they are 7.325 I could shim the llifter .045" and be right where I need to be with the current pushrods I have but I dont want to do that. So with that said, I have a set of brand new smith bros pushrods that have an over all length of 7.325" for sale. they are brand new never used. I paid 160ish for them. someone whoneeds this length pushrod make me an offer...
I have a set of smith bros. pushrods they are 7.325 I could shim the llifter .045" and be right where I need to be with the current pushrods I have but I dont want to do that. So with that said, I have a set of brand new smith bros pushrods that have an over all length of 7.325" for sale. they are brand new never used. I paid 160ish for them. someone whoneeds this length pushrod make me an offer...
08-23-2009, 09:17 AM
#11
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St. Jude Donor '09-'10-'11
Ok, I went out to the garage and followed the procedure Tom posted and it worked like a charm. The push rod length I need is 7.370 i checked it severl times all with the same results. I even checked the exhaust side and got the same results. now that ive done the procedure its real easy to do. thanks Tom. I have a set of smith bros. pushrods they are 7.325 I could shim the llifter .045" and be right where I need to be with the current pushrods I have but I dont want to do that. So with that said, I have a set of brand new smith bros pushrods that have an over all length of 7.325" for sale. they are brand new never used. I paid 160ish for them. someone whoneeds this length pushrod make me an offer...
I have a set of smith bros. pushrods they are 7.325 I could shim the llifter .045" and be right where I need to be with the current pushrods I have but I dont want to do that. So with that said, I have a set of brand new smith bros pushrods that have an over all length of 7.325" for sale. they are brand new never used. I paid 160ish for them. someone whoneeds this length pushrod make me an offer...Y2Kvert4me instructions are good. I hope the following doesn't confuse anything, but if your lifters are part number 17122490, then the full travel of the lifter adjustment range is .1662" (4.22mm). The production set point for this lifter is .0823"(2.09mm). There is a slight bias to toward the extended position of the lifter to account for valve and seat erosion/recession for the .0823" set point.
08-23-2009, 02:46 PM
#12
ISIS SUCKS FAT CHOAD
Thread Starter
What type of rockers are you using? If other then stock, did you check the stem wipe pattern?
Y2Kvert4me instructions are good. I hope the following doesn't confuse anything, but if your lifters are part number 17122490, then the full travel of the lifter adjustment range is .1662" (4.22mm). The production set point for this lifter is .0823"(2.09mm). There is a slight bias to toward the extended position of the lifter to account for valve and seat erosion/recession for the .0823" set point.
Y2Kvert4me instructions are good. I hope the following doesn't confuse anything, but if your lifters are part number 17122490, then the full travel of the lifter adjustment range is .1662" (4.22mm). The production set point for this lifter is .0823"(2.09mm). There is a slight bias to toward the extended position of the lifter to account for valve and seat erosion/recession for the .0823" set point.
Last edited by MVP'S ZO6; 08-23-2009 at 02:54 PM.
08-23-2009, 03:37 PM
#13
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St. Jude Donor '03
The OE lifters are very forgiving to preload variances.
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Generally, suggested preload will be about the mid point of the lifter's total travel range. The stock lifters (as stated) offer about .166" of it. Other aftermarket lifters don't have anywhere close to that amount of travel and can be much more fussy about correct preload.
The reason I gave you a range, is so that you could take your measurement and apply it to the closest stock-length pushrod, as they are generally stocked by suppliers in .025" increments.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
What was your actual measurement? (or turns of the pushrod checker)?
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Generally, suggested preload will be about the mid point of the lifter's total travel range. The stock lifters (as stated) offer about .166" of it. Other aftermarket lifters don't have anywhere close to that amount of travel and can be much more fussy about correct preload.
The reason I gave you a range, is so that you could take your measurement and apply it to the closest stock-length pushrod, as they are generally stocked by suppliers in .025" increments.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
What was your actual measurement? (or turns of the pushrod checker)?
08-23-2009, 04:26 PM
#14
ISIS SUCKS FAT CHOAD
Thread Starter
The OE lifters are very forgiving to preload variances.
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Generally, suggested preload will be about the mid point of the lifter's total travel range. The stock lifters (as stated) offer about .166" of it. Other aftermarket lifters don't have anywhere close to that amount of travel and can be much more fussy about correct preload.
The reason I gave you a range, is so that you could take your measurement and apply it to the closest stock-length pushrod, as they are generally stocked by suppliers in .025" increments.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
What was your actual measurement? (or turns of the pushrod checker)?
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Generally, suggested preload will be about the mid point of the lifter's total travel range. The stock lifters (as stated) offer about .166" of it. Other aftermarket lifters don't have anywhere close to that amount of travel and can be much more fussy about correct preload.
The reason I gave you a range, is so that you could take your measurement and apply it to the closest stock-length pushrod, as they are generally stocked by suppliers in .025" increments.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
What was your actual measurement? (or turns of the pushrod checker)?
Funny you should ask what the final amount of turns it took to collapse my checker. You were throwing out 9.5 in the how too you worte above. Now I know that was just a number you gave for reference purposes but you were close to the number of turns it took me to collapse the checker. It took me 10 turns exactly. 
08-23-2009, 05:12 PM
#15
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St. Jude Donor '09-'10-'11
The OE lifters are very forgiving to preload variances.
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
Just look at what most everyone else does - Stick 7.400" pushrods in everything, one size fits all.
Finding a 7.375" length "in stock" is not a problem...but if you really want a 7.370" or a 7.384" or whatever, that can be done too, but it will be a custom made job. But is .005" one way or the other going make any noticeable difference? No.
The primary reason for hydraulic lifters is to correct for stack-up variations during normal engine assemble and to account for changes over the life if the engine. As stated in the earlier post the target position is about half travel of the hydraulic lifter. In production it is slightly bias to the extended position, but as Y2Kvert4me stated, a little off one way or the other will not make a difference. 
08-23-2009, 05:45 PM
#16
ISIS SUCKS FAT CHOAD
Thread Starter
The primary reason for hydraulic lifters is to correct for stack-up variations during normal engine assemble and to account for changes over the life if the engine. As stated in the earlier post the target position is about half travel of the hydraulic lifter. In production it is slightly bias to the extended position, but as Y2Kvert4me stated, a little off one way or the other will not make a difference. to the both of you thank you for all of your help. Dont worry I'll be back if I need more. 
