Clattery M110 After Valve Adjust

[mosu]

73 M110...

Went through and checked all valve clearances again while I had he valve cover off to check the breather. All in spec, plenty of oil. I did notice on a couple of intake lobes that the sides of the cams are a little worn-in, with an ever-so-slight depression into the side of the lobe, rather then the little belly they normally have. The tip seemed fine to the eyeball.

Also, a pair of valves seemed to have uneven clearance on the feeler gauge. I adjusted to the tightest part being in spec...

Checked chain tension by pushing down onto the guardrail and it went down with a squirting noise from the tensioner, so I'm assuming that's fine...

Does the cam wear to clattery valves even when adjusted?

[kraakevik]

The chain tensioner ratchets inboard by tiny serrated steps to keep the cam chain almost dead tight against the tensioning rail, the only sliding rail with any play whatsoever.

If the chain has more than 1-2mm of slack under heavy thumb pressure you need a new or rebuilt chain tensioner and probably a new chain--loose chain tension will ultimately result in slipped camshaft gears and bent valves--good luck


Tim Kraakevik
kraakevik@voyager.net
Four M110's

[mosu]

Hmm, sounds like a new one's in order to play it safe. I think the chain is adding to the noise, but it's not the sole source. I-3 and I-1 are showing the wear pattern that I described in my initial post and they are definitely noisy, and definitely in spec around the cam's butt.

[kraakevik]

Sometimes installing new rocker arms mutes the noise of worn camshaft lobes for a few thousand miles--getting the timing train shipshape is surely the first priority--and adjusting the valves warm instead of cold (see hood plate for specs) seems to provide better clearances for real-life operation


Tim Kraakevik
kraakevik@voyager.net
Four M110's

[mbbuff]

What also happens with the M110's is that the cam housing journals become egg shaped with lots of miles, causing clatter after valve adjustment. The cam rides right on the housing.....no bearings/bushings. Usually the rears are worse than the fronts. So, if it's coming from the rear cylinder or two, that may be the cause. Cam housings are not cheap either.