Roller rocker preload - How much?
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From: Alabama
Roller rocker preload - How much?
Hi guys,
Just finished adjusting my valves (94 LT1 with LT4 hot cam with 1.6RR) and I set them to 0 lash plus 1 turn. I've been reading that people set them anywhere from 0 lash + 1/4 turn to 0 lash + the full turn.
What do you guys recommend?
Also if I have to change it can I just back them off a little or do I have to redo everything?
Thanks!
Just finished adjusting my valves (94 LT1 with LT4 hot cam with 1.6RR) and I set them to 0 lash plus 1 turn. I've been reading that people set them anywhere from 0 lash + 1/4 turn to 0 lash + the full turn.
What do you guys recommend?
Also if I have to change it can I just back them off a little or do I have to redo everything?
Thanks!
Melting Slicks
Joined: Sep 2010
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you are correct 1/4 - 1 turn
I do 3/4 turn from true 0 Lash
I would recommend. re-doing every rocker. if you change. to make them all even.
I have checked my poly lock vs set screw height after adjustment. with a dial caliper and reset to the adjustment reading. they all end up exact.
I do 3/4 turn from true 0 Lash
I would recommend. re-doing every rocker. if you change. to make them all even.
I have checked my poly lock vs set screw height after adjustment. with a dial caliper and reset to the adjustment reading. they all end up exact.
Last edited by THE 383 admiral; Mar 15, 2013 at 08:29 PM.
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From: Alabama
Thanks for the dial caliper idea I think I'll double check them with that tomorrow.
Also think i might drop down to 0 lash + 3/4 turn too just to be safe. I determined 0 lash by rolling the pushrod back and fourth until i felt slight resistance. I re did all of them 3 times. Never done valves before so the first two times was practice.
Also think i might drop down to 0 lash + 3/4 turn too just to be safe. I determined 0 lash by rolling the pushrod back and fourth until i felt slight resistance. I re did all of them 3 times. Never done valves before so the first two times was practice.
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I've typically done 1/4 turn with roller rockers and sometimes only 1/8 if using CompCams lifters. If you're just going to putter around the street, 3/4 will be fine but if you intend to really run it, I'd go 1/4 to account for the lifters pumping up a bit at continuous high rpm.
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From: Alabama
I've typically done 1/4 turn with roller rockers and sometimes only 1/8 if using CompCams lifters. If you're just going to putter around the street, 3/4 will be fine but if you intend to really run it, I'd go 1/4 to account for the lifters pumping up a bit at continuous high rpm.
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From: Alabama
The method I used was from: (http://shbox.com/1/4th_gen_tech2.html#adjust_valves)
"
Another cylinder by cylinder method that does not require looking at the balancer position, follows:
(A remote starter switch is quite helpful)
Turn the engine in the normal direction of rotation until the exhaust lifter for the cylinder you are adjusting starts to move up (valve begins to open).
On the intake rocker arm, adjust for zero lash and add your desired preload.
Turn the engine over again until the intake lifter on the same cylinder comes all the way up (valve open) and then goes almost all the way back down (valve almost closed) .
Now, adjust the rocker arm for the exhaust valve on that cylinder to zero lash and add your desired preload.
Continue the above procedure for each cylinder until all valves are adjusted to the same amount of preload. This procedure will work for any hydraulic lifter cam with adjustable rocker arms. Refer to this diagram posted above if you need visual reference. The reason I specify lifter movement in the above is because when you start off with completely loose rockers, there is no valve movement to watch. "
(A remote starter switch is quite helpful)
Turn the engine in the normal direction of rotation until the exhaust lifter for the cylinder you are adjusting starts to move up (valve begins to open).
On the intake rocker arm, adjust for zero lash and add your desired preload.
Turn the engine over again until the intake lifter on the same cylinder comes all the way up (valve open) and then goes almost all the way back down (valve almost closed) .
Now, adjust the rocker arm for the exhaust valve on that cylinder to zero lash and add your desired preload.
Continue the above procedure for each cylinder until all valves are adjusted to the same amount of preload. This procedure will work for any hydraulic lifter cam with adjustable rocker arms. Refer to this diagram posted above if you need visual reference. The reason I specify lifter movement in the above is because when you start off with completely loose rockers, there is no valve movement to watch. "
Le Mans Master
Joined: Mar 2004
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From: Dublin CA
You can't use the line up the timing mark on a 94 because there is none. You have to look at when the valves are opening.
Also, you indicated that you set the valves three times. A serious question at this point.....after you set them the first time with your full turn, did you go back and twist the rod again with you fingers until you felt resistance and then go another full turn?????????
If so then your valves are TOO tight and you have pushed the rod into the plunger on the hydraulic lifter. If you backed off the nut so there was lots of play in the rod and tried setting them again then you should be okay.
I am sending you a PM.
Also, you indicated that you set the valves three times. A serious question at this point.....after you set them the first time with your full turn, did you go back and twist the rod again with you fingers until you felt resistance and then go another full turn?????????
If so then your valves are TOO tight and you have pushed the rod into the plunger on the hydraulic lifter. If you backed off the nut so there was lots of play in the rod and tried setting them again then you should be okay.
I am sending you a PM.
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From: Slidell Louisiana
I've typically done 1/4 turn with roller rockers and sometimes only 1/8 if using CompCams lifters. If you're just going to putter around the street, 3/4 will be fine but if you intend to really run it, I'd go 1/4 to account for the lifters pumping up a bit at continuous high rpm.
On the vette I've been running 0 +1/4 turn set hot with engine running. But I can't afford for the lifters to pump up at speed. For the Impala I followed the old EO IC method with engine OFF and 3/4 turn, but that LT1 was entirely stock.MIke
Le Mans Master
Joined: Mar 2004
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From: Dublin CA
If you are not sure what the EO IC means ......Exhaust valve Open (look for relationship with the valve and the exhaust manifold if you are not sure) and Intake valve Closed.......adjust the intake.
Le Mans Master
Joined: May 2004
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From: Hellinois
Finalist 2020 C4 of the Year - Modified
Personally I prefer to move the rocker up & down as opposed to spinning the pushrod. I use the same procedure John A Marker explained, I've found it to be much more accurate. I feel there is too much chance to be able to spin the pushrod after 0 lash. I have also found 1/2 turn after 0 to be the best.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
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From: Dublin CA
Joe C.....are you out there
Since there are so many new members here I am copying a post from a few years back. Full credit goes to Forum member Joe C.. I have adjusted valves for 40 plus years and after using Joe's method, I have never questioned getting the adjustment right.
BTW, I tried something a little unconventional on adjusting hydraulic lifters. one thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. so I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. {place the feeler gauge between the top of the valve stem and the rocker arm.} When I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. at that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. if you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...
again, thanks for all your help - take care -
JoeC
BTW, I tried something a little unconventional on adjusting hydraulic lifters. one thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. so I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. {place the feeler gauge between the top of the valve stem and the rocker arm.} When I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. at that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. if you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...
again, thanks for all your help - take care -
JoeC
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From: Alabama
Just got done adjusting my valves. I used Joe C. 's Method posted by John Marker using the feeler gauges. Great way to get consistency. Also just to note I used the 3/4 turn and I have stock lifters. Now just have to wait to get my PCM back from the tuners then I can see how it runs. Thanks for the help guys!