Well, maybe. One thing you should know is what sort of push rods you have. If alloy (whatever that means; others here can be more specific)you may have just set the gap too big. The alloy push rods expand at same rate as the case/valve combo, so need no big gap to save the valves. They say (zero) gap, but always good to have a little, say 0.001 in. If you have "ordinary" push rods (steel??) then proper "lash" is in order. The exact dimensions to use escape me at the moment, but a call to the engine builder should reveal all. If there is no reliable data, I do not know how one would determine which type of push rods you have. Perhaps the use of a magnet would reveal. Would have to rely on Dr. Clock, Wolfgang, Gordon (of Five Cent Racing fame), Pip, or other sharp air-cooled guy to 'splain about that... If you have the alloys and set 0.012 gap, I'd say no wonder you have some noise. That the noise is all from one cylinder/valve would be troublesome, I'll grant you that. If an exhaust valve is burned, a quick compression check would reveal that. I toasted an exhaust valve on my old S90 Coupe many years ago, and it makes a very distinctive noise. Do not assume the worst, and do the easy troubleshooting first. Seems to me if compression on 1 out of four is bad from exhaust valve leaking, then power should be down noticeably -- how about that? Engine still have spunk?? All else fails, then might be time to drop the engine and look at the heads. Aside from being real careful about the order in which you remove and replace head bolts (and mind the torque settings), that job is not too hard. If you need to have the valve replaced, chances are the seat might be in trouble too -- a proper AIR COOLED shop will be able to help you w/ that: diagnosis and fix too. Worst case, you'd need a new head as well as a new valve. Tiffs, or Cory's favorite place in Annapolis should know the particulars about that. Were you running the engine w/ valve covers off?? That would be messy . . .
OK East Coast brain trust, chime in and tell us where we've gone wrong here.
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