Valve Lash Adjustments
01-07-2008, 07:45 PM
#1
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Thread Starter
Join Date: Jul 2007
Location: Ohio
Posts: 37
Valve Lash Adjustments
I was wondering if I could get some opinions on how (everyone) sets there valve lash adjustment? I've heard lots of story's and here soon I need to set my mine. I've already been to shoebox.com (I'm just looking for opinions here).
01-07-2008, 08:30 PM
#4
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Join Date: Jan 2005
Location: Moore Oklahoma
Posts: 1,388
This is how I do mine.
WD
Hydraulic Lifter Pre-Load Adjustment
What is Hydraulic Lifter Preload? Mechanical cam designs require a running clearance or valve lash; hydraulic lifters are just the opposite. When the rocker arm assembly is properly adjusted, the pushrod must take up all the clearance and descend into the hydraulic lifter, causing the pushrod seat to move down by .020 to .060. The distance that the pushrod seat moves down away from the retaining lock is the Lifter Preload. The hydraulic mechanism requires this precise amount of preload for it to do its job properly.
What happens if the amount of Hydraulic Lifter Preload is wrong? If clearance exists between the pushrod and the seat in the hydraulic lifter, after the rocker arm assembly has been adjusted, you will have no lifter preload. In this case the valve train will be noisy when the engine is running. All of the hydraulic force produced by the lifter will be exerted against the lifters retaining lock, and this could cause the lock to fail.
If the opposite occurs and the pushrod descends too far (more than .060?), then you have excessive lifter preload. In theory, a hydraulic lifter can pump up whatever preload you put into it, therefore with excessive preload, as the engine RPM and oil pressure increases, the hydraulic mechanism will pump-up the pushrod seat. This will cause the valve to be open longer and lift higher. This will decrease the cylinder pressure, lowering the performance of the engine. If the preload is excessive it may cause backfiring from the engine. How to correct this situation will be explained in the next sections.
Methods to Adjust for Proper Hydraulic Lifter Preload
Hydraulic Lifters Can Be Adjusted at Any Engine Temperature Since hydraulic lifters can compensate for thermal expansion of the engine, the adjusting can be done with the engine cold; hot adjustment is not necessary. Adjusting Hydraulic Lifters for Proper Preload: In order to adjust the preload the lifter must be properly located on the base circle or Heel of the lobe. At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.
1. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinders “intake” rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
2. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
3. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at Zero Lash. Turn the adjusting nut down one quarter (1/4), or one half turn (1/2) from that point. Lock the adjuster into position. The intake is now adjusted properly. Most high performance applications use ¼ turn.
4. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When that intake is almost closed, stop and adjust the “exhaust” rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
5. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
Do Hydraulic Lifters Need to be Primed with Oil? Many people mistakenly believe that hydraulic lifters must be soaked in oil overnight and be hand pumped up with a pushrod before installing into a new engine, this is not necessary. In fact, this could cause the lifter to act as a solid and prevent obtaining proper preload.
WD
Hydraulic Lifter Pre-Load Adjustment
What is Hydraulic Lifter Preload? Mechanical cam designs require a running clearance or valve lash; hydraulic lifters are just the opposite. When the rocker arm assembly is properly adjusted, the pushrod must take up all the clearance and descend into the hydraulic lifter, causing the pushrod seat to move down by .020 to .060. The distance that the pushrod seat moves down away from the retaining lock is the Lifter Preload. The hydraulic mechanism requires this precise amount of preload for it to do its job properly.
What happens if the amount of Hydraulic Lifter Preload is wrong? If clearance exists between the pushrod and the seat in the hydraulic lifter, after the rocker arm assembly has been adjusted, you will have no lifter preload. In this case the valve train will be noisy when the engine is running. All of the hydraulic force produced by the lifter will be exerted against the lifters retaining lock, and this could cause the lock to fail.
If the opposite occurs and the pushrod descends too far (more than .060?), then you have excessive lifter preload. In theory, a hydraulic lifter can pump up whatever preload you put into it, therefore with excessive preload, as the engine RPM and oil pressure increases, the hydraulic mechanism will pump-up the pushrod seat. This will cause the valve to be open longer and lift higher. This will decrease the cylinder pressure, lowering the performance of the engine. If the preload is excessive it may cause backfiring from the engine. How to correct this situation will be explained in the next sections.
Methods to Adjust for Proper Hydraulic Lifter Preload
Hydraulic Lifters Can Be Adjusted at Any Engine Temperature Since hydraulic lifters can compensate for thermal expansion of the engine, the adjusting can be done with the engine cold; hot adjustment is not necessary. Adjusting Hydraulic Lifters for Proper Preload: In order to adjust the preload the lifter must be properly located on the base circle or Heel of the lobe. At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.
1. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinders “intake” rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
2. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
3. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at Zero Lash. Turn the adjusting nut down one quarter (1/4), or one half turn (1/2) from that point. Lock the adjuster into position. The intake is now adjusted properly. Most high performance applications use ¼ turn.
4. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When that intake is almost closed, stop and adjust the “exhaust” rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
5. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
Do Hydraulic Lifters Need to be Primed with Oil? Many people mistakenly believe that hydraulic lifters must be soaked in oil overnight and be hand pumped up with a pushrod before installing into a new engine, this is not necessary. In fact, this could cause the lifter to act as a solid and prevent obtaining proper preload.
01-07-2008, 09:00 PM
#5
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Join Date: Nov 2007
Posts: 0
Doing it while its running is one of the best ways to adjust valves, ive done it that way for years and they are perfect everytime. In my opinion doing it while running is the only way I can get them perfect, the other ways ive tried some have ither been too tight, or too loose. thats just me though, im sure there will be some guys who disagree with me....
01-08-2008, 09:11 AM
#8
Registered User
Join Date: Aug 2007
Posts: 305
Doing a runing adjustment is not nessicary.
It gets very messy once the oil starts flowing, plus you are breating all of that exhaust, not to mention hot underhood parts ect. I used to do running adjustments all the time, it's really just better/ more comfortable to adjust them with the engine off.
Adjusting valves is easy. This is my method.
1) Install pushrods and rocker arms
2) By hand install all of the locking nuts (do not install locks at this time, compleetly remove them and set them aside).
3) Turn the engine over untill some of the valves are in the open posion. Keep rotating the crank untill you observe maximum lift. You don't need a dial indicator here just close 'nuf.
4) You are now ready to adjust the adjasent rocker arm of the same cylinder.
Note: Step #3 insures that the lifter is on the base circle of the cam. If the lifter is any where on the lift part you will adjust the rockers wrong! This is because you are now tightening against the valve spring and lifter, this will make the rocker higher than it needs to be. You will notice that on the next engine rotation that particular rocker will not be adjusted right. Step #3 also assumes that the intake is on the engine and you can't see the lifters.
5) Loosen the adjusting nut untill the rocker just flopps arround.
6) Begin tightening the nut by hand while lifting up and down on the rocker arm on the push rod side. (forget that spin push rod garbage )
7) Continue tightening by hand untill the rocker arm has no vertical movement. This is zero lash.
8) At this point a decision needs to be made with regard to your preload setting. A stock hydraulic lifter takes between 1/4 and 1/2 turn, still other lifters require less like 1/16th tun, and some lifters either run at zero or with lash in which case you would need a feeler gauge. Consult the lifter manufactureure for this part.
9) Install the nut lock. Thread them in by hand.
10) Grab a box end wrench and hold back the nut while you tighten the lock. Use a medium length allen wrench and snug it down pretty tight. I typically use my thumb untill I get some wrench deflection.
11) Lastly take the box end wrench and tighten the nut another degree or two. This will ensure that the locks are set.
NOTE: When removing the nut (for any reason) don't break them loose at the lock. Instead, loosen the nut first then hold back the nut while you remove the lock. This will help preserve the threads on the locks and nuts.
Thats it! Then continue down the line roating and adjusting untill you run out of locks.
The oil pressure guage being maxed out at key on is a sign of a broken wire, check with a standard mechanical gauge to be sure. Another thing to remember is a fresh engine will make noise. It usually takes between 1-5 minutes for everything to quiet down. This is true if everything is adjusted properly. Be sure to check your pushrods for pluged oil holes.
Good luck.
__________________
this was copied from another thread.
It gets very messy once the oil starts flowing, plus you are breating all of that exhaust, not to mention hot underhood parts ect. I used to do running adjustments all the time, it's really just better/ more comfortable to adjust them with the engine off.
Adjusting valves is easy. This is my method.
1) Install pushrods and rocker arms
2) By hand install all of the locking nuts (do not install locks at this time, compleetly remove them and set them aside).
3) Turn the engine over untill some of the valves are in the open posion. Keep rotating the crank untill you observe maximum lift. You don't need a dial indicator here just close 'nuf.
4) You are now ready to adjust the adjasent rocker arm of the same cylinder.
Note: Step #3 insures that the lifter is on the base circle of the cam. If the lifter is any where on the lift part you will adjust the rockers wrong! This is because you are now tightening against the valve spring and lifter, this will make the rocker higher than it needs to be. You will notice that on the next engine rotation that particular rocker will not be adjusted right. Step #3 also assumes that the intake is on the engine and you can't see the lifters.
5) Loosen the adjusting nut untill the rocker just flopps arround.
6) Begin tightening the nut by hand while lifting up and down on the rocker arm on the push rod side. (forget that spin push rod garbage )
7) Continue tightening by hand untill the rocker arm has no vertical movement. This is zero lash.
8) At this point a decision needs to be made with regard to your preload setting. A stock hydraulic lifter takes between 1/4 and 1/2 turn, still other lifters require less like 1/16th tun, and some lifters either run at zero or with lash in which case you would need a feeler gauge. Consult the lifter manufactureure for this part.
9) Install the nut lock. Thread them in by hand.
10) Grab a box end wrench and hold back the nut while you tighten the lock. Use a medium length allen wrench and snug it down pretty tight. I typically use my thumb untill I get some wrench deflection.
11) Lastly take the box end wrench and tighten the nut another degree or two. This will ensure that the locks are set.
NOTE: When removing the nut (for any reason) don't break them loose at the lock. Instead, loosen the nut first then hold back the nut while you remove the lock. This will help preserve the threads on the locks and nuts.
Thats it! Then continue down the line roating and adjusting untill you run out of locks.
The oil pressure guage being maxed out at key on is a sign of a broken wire, check with a standard mechanical gauge to be sure. Another thing to remember is a fresh engine will make noise. It usually takes between 1-5 minutes for everything to quiet down. This is true if everything is adjusted properly. Be sure to check your pushrods for pluged oil holes.
Good luck.
__________________
this was copied from another thread.
01-08-2008, 09:58 AM
#9
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Join Date: Dec 1969
Location: PORTLAND, OR, MULTNOMAH
Posts: 3,499
As mentioned, the tighter the preload at 0.050 lift , the longer the duration which may be desireable for top end, while the looser the preload the more power at the bottom end and supposedly better 60s.
One thought is that for every .004 over or under factory setttings you get 2% more or less duration. I understand that GM recommends one full turn, however I haven't a clue what that represents in terms of preload.
Usually 1/2 turn does the trick, however, I turned mine another 1/2 turn to quiet it down some.
I guess the optimum way to see what is the best preload would be to either on a dyno or the track.
You're probably safe between 1/4 and 1 full turn for normal operation, however, the deciding factor in
winning or losing a race might depend on getting the best preload.
I figured, wrongly no doubt, that since I am running an
RV cam with 4:10 rear end that my bottom end torque is covered. Since I am running shorties, I figure that going with a tighter preload will help me a bit on the top end. Dunno.
One thought is that for every .004 over or under factory setttings you get 2% more or less duration. I understand that GM recommends one full turn, however I haven't a clue what that represents in terms of preload.
Usually 1/2 turn does the trick, however, I turned mine another 1/2 turn to quiet it down some.
I guess the optimum way to see what is the best preload would be to either on a dyno or the track.
You're probably safe between 1/4 and 1 full turn for normal operation, however, the deciding factor in
winning or losing a race might depend on getting the best preload. I figured, wrongly no doubt, that since I am running an
RV cam with 4:10 rear end that my bottom end torque is covered. Since I am running shorties, I figure that going with a tighter preload will help me a bit on the top end. Dunno.
01-08-2008, 07:11 PM
#10
Guest
Join Date: Nov 2007
Posts: 0
Doing a runing adjustment is not nessicary.
It gets very messy once the oil starts flowing, plus you are breating all of that exhaust, not to mention hot underhood parts ect. I used to do running adjustments all the time, it's really just better/ more comfortable to adjust them with the engine off.
Adjusting valves is easy. This is my method.
1) Install pushrods and rocker arms
2) By hand install all of the locking nuts (do not install locks at this time, compleetly remove them and set them aside).
3) Turn the engine over untill some of the valves are in the open posion. Keep rotating the crank untill you observe maximum lift. You don't need a dial indicator here just close 'nuf.
4) You are now ready to adjust the adjasent rocker arm of the same cylinder.
Note: Step #3 insures that the lifter is on the base circle of the cam. If the lifter is any where on the lift part you will adjust the rockers wrong! This is because you are now tightening against the valve spring and lifter, this will make the rocker higher than it needs to be. You will notice that on the next engine rotation that particular rocker will not be adjusted right. Step #3 also assumes that the intake is on the engine and you can't see the lifters.
5) Loosen the adjusting nut untill the rocker just flopps arround.
6) Begin tightening the nut by hand while lifting up and down on the rocker arm on the push rod side. (forget that spin push rod garbage )
7) Continue tightening by hand untill the rocker arm has no vertical movement. This is zero lash.
8) At this point a decision needs to be made with regard to your preload setting. A stock hydraulic lifter takes between 1/4 and 1/2 turn, still other lifters require less like 1/16th tun, and some lifters either run at zero or with lash in which case you would need a feeler gauge. Consult the lifter manufactureure for this part.
9) Install the nut lock. Thread them in by hand.
10) Grab a box end wrench and hold back the nut while you tighten the lock. Use a medium length allen wrench and snug it down pretty tight. I typically use my thumb untill I get some wrench deflection.
11) Lastly take the box end wrench and tighten the nut another degree or two. This will ensure that the locks are set.
NOTE: When removing the nut (for any reason) don't break them loose at the lock. Instead, loosen the nut first then hold back the nut while you remove the lock. This will help preserve the threads on the locks and nuts.
Thats it! Then continue down the line roating and adjusting untill you run out of locks.
The oil pressure guage being maxed out at key on is a sign of a broken wire, check with a standard mechanical gauge to be sure. Another thing to remember is a fresh engine will make noise. It usually takes between 1-5 minutes for everything to quiet down. This is true if everything is adjusted properly. Be sure to check your pushrods for pluged oil holes.
Good luck.
__________________
this was copied from another thread.
It gets very messy once the oil starts flowing, plus you are breating all of that exhaust, not to mention hot underhood parts ect. I used to do running adjustments all the time, it's really just better/ more comfortable to adjust them with the engine off.
Adjusting valves is easy. This is my method.
1) Install pushrods and rocker arms
2) By hand install all of the locking nuts (do not install locks at this time, compleetly remove them and set them aside).
3) Turn the engine over untill some of the valves are in the open posion. Keep rotating the crank untill you observe maximum lift. You don't need a dial indicator here just close 'nuf.
4) You are now ready to adjust the adjasent rocker arm of the same cylinder.
Note: Step #3 insures that the lifter is on the base circle of the cam. If the lifter is any where on the lift part you will adjust the rockers wrong! This is because you are now tightening against the valve spring and lifter, this will make the rocker higher than it needs to be. You will notice that on the next engine rotation that particular rocker will not be adjusted right. Step #3 also assumes that the intake is on the engine and you can't see the lifters.
5) Loosen the adjusting nut untill the rocker just flopps arround.
6) Begin tightening the nut by hand while lifting up and down on the rocker arm on the push rod side. (forget that spin push rod garbage )
7) Continue tightening by hand untill the rocker arm has no vertical movement. This is zero lash.
8) At this point a decision needs to be made with regard to your preload setting. A stock hydraulic lifter takes between 1/4 and 1/2 turn, still other lifters require less like 1/16th tun, and some lifters either run at zero or with lash in which case you would need a feeler gauge. Consult the lifter manufactureure for this part.
9) Install the nut lock. Thread them in by hand.
10) Grab a box end wrench and hold back the nut while you tighten the lock. Use a medium length allen wrench and snug it down pretty tight. I typically use my thumb untill I get some wrench deflection.
11) Lastly take the box end wrench and tighten the nut another degree or two. This will ensure that the locks are set.
NOTE: When removing the nut (for any reason) don't break them loose at the lock. Instead, loosen the nut first then hold back the nut while you remove the lock. This will help preserve the threads on the locks and nuts.
Thats it! Then continue down the line roating and adjusting untill you run out of locks.
The oil pressure guage being maxed out at key on is a sign of a broken wire, check with a standard mechanical gauge to be sure. Another thing to remember is a fresh engine will make noise. It usually takes between 1-5 minutes for everything to quiet down. This is true if everything is adjusted properly. Be sure to check your pushrods for pluged oil holes.
Good luck.
__________________
this was copied from another thread.
it is really not that messy on a lt1 motor, I ushally put a piece of cardboard between the head and springs and no oil gets on the headers. also if your good at it adjusting while running can be very fast and done withing 10 min....I really believe it is the best way to adjust valves..
01-08-2008, 08:07 PM
#11
Registered User
Join Date: Dec 1969
Location: Little Rock, AR
Posts: 27,714
it is really not that messy on a lt1 motor, I ushally put a piece of cardboard between the head and springs and no oil gets on the headers. also if your good at it adjusting while running can be very fast and done withing 10 min....I really believe it is the best way to adjust valves..
There is no need to quibble over what is best. It is a personal preference and all methods are accurate. Over the years, I've used them all.
04-10-2008, 09:02 AM
#14
Registered User
Join Date: Jan 2004
Location: Downey, CA
Posts: 1,406
Just a note that the factory recommended preload is 1 turn with the 3/8-24 stud which is 0.042"
and with a 7/16-20 stud one turn is 0.050". If you want to match the factory spec with 7/16
studs you need to set the preload a tad past 3/4 turn.
and with a 7/16-20 stud one turn is 0.050". If you want to match the factory spec with 7/16
studs you need to set the preload a tad past 3/4 turn.
04-10-2008, 11:24 AM
#15
Registered User
Join Date: Jun 2003
Location: Saginaw, Michigan
Posts: 3,620
Is there a link to this? I set my 7/16" studs to 3/8 turn based on some information that I looked up years ago based on GM preload specs, but can't find it now. It's rans great, and quiet.
Dan