Hi all,
Just a quick question to the engine guru's amongst us on using feeler gauges to adjust the valve lash/clearance on the rockers (we're talking solid cam here)....
Basically, I want to know how fussy you get with your technique and how to get the clearances absolutely 'spot-on'. Let's say we're setting the valve lash to 0.020". Using a 0.020" feeler gauge - should it feel semi 'loose' and easy to move when sliding back and forth, 'medium', or totally rock hard??? ie. say you set it firmly at 0.020", but then grab a 0.021" feeler gauge and it still squeezes in if you try real hard. Is that alright, or should the 0.020" be set harder so that nothing else can get through.
In the past I've always had a hydraulic cam, so setting valve lash was never required. Now that I'm getting into the routine though with my solid, I want to know the exact, most precise way to set the lash every time. Guess what I'm doing this Saturday! Then back onto the dyno real soon.....
Feedback would be greatly appreciated. Thanks!
Brett.
"Feeling" the clearance (Adjusting roller rockers)
Started by
LXCHEV
, Jun 06 2006 10:34 PM
9 replies to this topic
#1
LXCHEV
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Posted 06 June 2006 - 10:34 PM
#2
TerrA LX
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Posted 06 June 2006 - 10:36 PM
I here the dyno is the best place to set the lash.
#3
makka
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Posted 06 June 2006 - 10:47 PM
it should be firm Brett, not too tight
#4
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Posted 06 June 2006 - 11:09 PM
Yeah, good question Brett, I'll be doing mine soon so something I would appreciate knowing too!!
#5
_Lostit_
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Posted 07 June 2006 - 08:47 AM
Firm , i set mine to.
And you really want to check em after the motor is warm , yeap its a bitch when everything is hot LOL.
People say you got to check em regularly but thats full of crap, ive done probadly 2-3000km and no problems and it still spins to 7krpm without hestiation. But i do have a hacit every oil change i check the rockers.. which is every 5000kms.
Just make sure the rockers are unloaded and really some cams have different settings for intake and exhaust but i guess that will confuse you even more, and there is a pattern to it .Oh yeah if your battery is on the weak side might be better to pull the plugs out so your battery doesnt run out .
Denis
And you really want to check em after the motor is warm , yeap its a bitch when everything is hot LOL.
People say you got to check em regularly but thats full of crap, ive done probadly 2-3000km and no problems and it still spins to 7krpm without hestiation. But i do have a hacit every oil change i check the rockers.. which is every 5000kms.
Just make sure the rockers are unloaded and really some cams have different settings for intake and exhaust but i guess that will confuse you even more, and there is a pattern to it .Oh yeah if your battery is on the weak side might be better to pull the plugs out so your battery doesnt run out .
Denis
#6
Dr Terry
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Posted 07 June 2006 - 08:54 AM
Hi Brett.
Adjusting tappet clearances is an art that takes practice, but I only just noticed in your post that you are adjusting them with roller rockers.
The main thing with rollers is to pull the feeler gauge in & out 'sideways'. By that I meah parallel to the roller tip's axis, not making the roller tip rotate. If you make the roller tip rotate, you will have very little feel.
Dr Terry.
Adjusting tappet clearances is an art that takes practice, but I only just noticed in your post that you are adjusting them with roller rockers.
The main thing with rollers is to pull the feeler gauge in & out 'sideways'. By that I meah parallel to the roller tip's axis, not making the roller tip rotate. If you make the roller tip rotate, you will have very little feel.
Dr Terry.
#7
LXCHEV
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Posted 07 June 2006 - 04:51 PM
Thanks guys, exactly what I wanted to know Dr Terry! Will use the 'sideways' technique now that I know for sure.
Denis - yeah my cam has 2 different profiles, so I have to set the intakes and exhausts to different specs. I have a good procedure for adjusting them all in turn (ensuring each valve is fully shut ie. on the back of the cam lobe), so the pattern is not a worry, as long as I don't get interrupted! I will definitely be doing it hot, and last time I just turned the engine over by hand with a long arm bar (to save both my starter and my battery!).
Many thanks for all the feedback guys, very much appreciated.
Liam, looks like we both have the answers we wanted! I'll race ya!!!!!!!
Denis - yeah my cam has 2 different profiles, so I have to set the intakes and exhausts to different specs. I have a good procedure for adjusting them all in turn (ensuring each valve is fully shut ie. on the back of the cam lobe), so the pattern is not a worry, as long as I don't get interrupted! I will definitely be doing it hot, and last time I just turned the engine over by hand with a long arm bar (to save both my starter and my battery!).
Many thanks for all the feedback guys, very much appreciated.
Liam, looks like we both have the answers we wanted! I'll race ya!!!!!!!
#8
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Posted 07 June 2006 - 06:59 PM
Race, no one told me this was a race!! I'll just let you win then you have to come around and "show" me how to do it 
#9
LXCHEV
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Posted 07 June 2006 - 11:19 PM
Hahaha good call! But I will be out test driving! 
#10
_LX406_
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Posted 08 June 2006 - 10:09 AM
Hey brett. I have dont the rocker lash settings about 1000 times in the 400 chev. I used to do it before every race meeting in the torana, but lately in the HG I do it every now and then it usually doesn't need much adjusting. The guy at Crow cams told me the springs will be ok if you drive it a fair bit. No need to back em off between meetings.
I have the firing order written in texta on the garage wall. But you split the firing order in 2. 1st 4 on top, 2nd 4 underneath. eg:
(forgive me if this is the wrong order, example only)
1278
4563
When no 4 cyl rockers are rocking, that means no 1 cyl is on the back of the cam and can be adjusted. etc 2 & 5 7&6 8&3
Hope this is clear
I have the firing order written in texta on the garage wall. But you split the firing order in 2. 1st 4 on top, 2nd 4 underneath. eg:
(forgive me if this is the wrong order, example only)
1278
4563
When no 4 cyl rockers are rocking, that means no 1 cyl is on the back of the cam and can be adjusted. etc 2 & 5 7&6 8&3
Hope this is clear
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