Intermittent sticking valve

[Mark's 37]

Originally Posted by cajunfirehawk

IMHO I would imagine you would have to post the video to youtube or some hosting site like that and then just put the link in this thread? I think Ryan has file size restrictions on this forum? If you don't know how u can try to email me the file and Ill do it for you, I don't mind...Pm for email info.

Try this:

https://youtu.be/JXhnf2O3fwQ

[cajunfirehawk]

Originally Posted by Mark's 37

Try this:

https://youtu.be/JXhnf2O3fwQ

That works, you get a higher vacuum reading than I do, I get about 18 lbs but not sure how accurate my 20-30 yr old sears vacuum gauge is? And



FWIW, I think I have a slight valve sticking issue too, I tired to video my exhaust one day to reproduce it but you cant hear it when I move the phone under the car.
https://youtu.be/KgesiRUu0mw

[Tinker]

Originally Posted by Mark's 37

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.

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.


.

[meric42]

Originally Posted by GOSFAST

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!

Where can one buy these guides and seals?

[Phil Gillespie]

Originally Posted by meric42

Where can one buy these guides and seals?

Can be purchased from Gary on this site. Have them plus the inlet valve seals on my 81A engine.
Phil NZ