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+--- Thread: Adjusting the valves with different valve lash. (/showthread.php?tid=76)
Adjusting the valves with different valve lash. - forkintheforest - 08-07-2008
What would happen if you added a little extra clearance when adjusting the valves? I'm talking about like Intake .25mm and Exhaust .45mm would it improve anything. I remember reading somewhere the more valve lash there is the louder the valve sound would be. And what would happen if you only increased the valve lash on the exhaust side of things. Would that create a better scavenging effect? Just wondering. Thanks
Re: Adjusting the valves with different valve lash. - winmutt - 08-07-2008
Decrease in performance as the time that the valves stayed open would be shorter.
Re: Adjusting the valves with different valve lash. - forkintheforest - 08-08-2008
Annnd, if you adjusted them tighter then spec it would be better performance? Or only in theory because, they would be slightly in the combustion chamber on the combustion stroke and it would burn the valves right? Something like that?
Re: Adjusting the valves with different valve lash. - winmutt - 08-08-2008
forkintheforest Annnd, if you adjusted them tighter then spec it would be better performance? Or only in theory because, they would be slightly in the combustion chamber on the combustion stroke and it would burn the valves right? Something like that?Nope to tight and you end up with open valves during combustion. Lower compression. Less HP.
Re: Adjusting the valves with different valve lash. - ForcedInduction - 08-09-2008
Winmutt got it right. The lash specs MB chose are for a reason. As the engine heats up the gap they set closes to almost nothing. Too loose and the valves are open for less time, too tight and the valves are held slightly open. Both result in reduced power, tight lash can cause accelerated cam wear.
Re: Adjusting the valves with different valve lash. - forkintheforest - 08-09-2008
Ok, cool. Just wondering you know. Mainly cause I thought about how if you buy aftermarket cams they have all these different ratings. and I thought "Hmm, I wonder if you can do basically the same thing just by adjusting the clearance a little differently. But, since you told me either way I'd be mucking it up I'll go ahead and leave them at the stock clearance. Btw, whats "excessive" cam wear?
Re: Adjusting the valves with different valve lash. - ForcedInduction - 08-10-2008
A shape that is not like an egg, has grooves, pits or discoloration (bluing from heat).
Here are some examples.
![[Image: Worncam1178.jpg]](http://members.cox.net/lnewcomb99/Pics/Worncam1178.jpg)
![[Image: worncamalertbadcam.jpg]](http://members.cox.net/lnewcomb99/Pics/worncamalertbadcam.jpg)
Re: Adjusting the valves with different valve lash. - winmutt - 08-10-2008
lolz wow is that second pic an om6XX?
Fork, most after market cams have longer lobes allowing for more gasses to pass through during the specified interval. Others also change the valve timing as well.
Re: Adjusting the valves with different valve lash. - ForcedInduction - 08-10-2008
winmutt Fork, most after market cams have longer lobes allowing for more gasses to pass through during the specified interval.
Mercedes did this with the OM617a in 1980 when they increased the lift which gave enough airflow for 13hp (110-123hp).