I adjusted my intake valve clearances a while back to specs - they were off by about .001-.002". Now, though, I'm getting a very slight tapping when warm, not really enough to concern me, but want to know if I should be concerned if the clearances are open too much by at most .001". I plan to recheck in the future, but should I make this a priority?

Just checked the archives and found a post claiming that since the engine was designed to use leaded gas, the valve clearances are very important (answered my question I guess!). Spurs a second question of whether any clearance modifications should be made if I'm using unleaded? Any other changes?

[This message has been edited by wjbell (edited 05-31-2000).]

WJ
I check the valve clearance on my 71 250C every two oil changes (6000 miles). I use the "go-nogo" method. Example, .003 fits, .004 will not fit. Since the gaps are "designed" to allow for thermal expansion to maintain the proper clearance, I don't believe any clearance mods are necessary. Perhaps some of the MB techs have a better handle on this one. I, too, get a light tapping when warm. My engine has 130K and the chain/tensioners are good so I have never felt there to be a problem for me.

BTW: I also run a bottle of Redline Total Fuel System stuff every two oil changes also.
Don't know for sure why I really do that - I think it just feels good (or something).

Anyhow, based on my experience (and my 250C is a "daily driver" - except in foul weather) I don't think you have a problem. However, as I stated earlier, perhaps some of the MB techs with all of the "good knowledge" have a better handle on this.

Enjoy the car

Dan


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Dan Taylor/ Tulsa, OK MBCA '71 250C/'81 300TD-T

[This message has been edited by DANTRCAV (edited 06-01-2000).]

.001 is a good percentage of the lash.

The guy who worked on my 250C's (great cars!) believes that you should just barely be able to pull the guage through. He also rotated the engine until the appropriate lobe was in the middle of the closed position to adjust. He did them one at a time.

Have fun!


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Chuck Taylor
Falls Church VA
'86 300E 5 speed
'95 C220 (wife's car)
'98 Porsche Boxster
Past: '79 280E, '82 300D (18 yrs), '77 240D,
4 250C's