Intermittent sticking valve

Mark's 37 said:
Today I added MMO to the gas tank, 5 ounces, then changed the oil with 5-20 Mobil 1 with about a quart of MMO. Fired it up and let it warm up then poured about 3 ounces of MMO slowly down the carb. Still an irregular fluttering but not as pronounced. I tried to upload a video of the vacuum gauge with the engine idling but couldn't get it to load on this page. I am cautious about putting too much MMO into the carb because of worry about fouling the plugs. I drove it about 4 miles afterward. I will put a few more miles and see what happens. The symptoms changed somewhat as it is more fluttering with a small cylinder drop intermittently. Not right.
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Plugs can be cleaned. It usually takes some time and may need to be repeated a few times. I don't put any in the oil, sometimes in the gas tank.


But it could be something else too. MMO is fairly cheap to buy and try. Assume the valve adjustment job went well.


From the video you have some valve flutter (sticking, I guess technically valve flutter is something different...but ya fluttering valves). Keep driving it. Engines need to be run and under load not just in the garage. Do it again then drive the piss out of it for 10-20 miles.


If you feel something else is majorly wrong... don't drive it hard.


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GOSFAST said:
Hi Mark, can't help locating the "offender", but I can give you this: when we come across anyone in the beginning or the middle of a fresh build we tell them to install bronze-lined guides. I can all but guarantee you'll NEVER experience any "hung" valves anymore!

Thanks, Gary in N.Y.

P.S. Whether or not this is your issue the lined guides are really a must-have in the build regardless! We're literally still doing hundreds every year and have been for a very long time now, stainless valves and the bronze guides, never look back!
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Where can one buy these guides and seals?
 
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