Can't get rid of cough sa 200

[RyeGuy]

Hey guys I have a 57 200 that has a cough I can't get rid of. Bought it a couple years ago did a tune up and some work on it ( rebuilt carb, new plugs and wires, new points, coil, condenser, cap etc)when I got it and was running good but a miss during idle. So a month ago I went in checked valve lash which was all pretty close. Rebuilt carb again, put in inline fuel filter, new manifold gasket, new plugs, new points. And now the miss/cough is worse, idle fine for 10sec or so then misses and goes back to smooth idle etc etc. Have went thru everything 5 times. Cleaned gas tank etc.
Things I'm not 100% sure on: I Set points to .015 at high cam. You set it when it's at high cam right?
Took off mag, and cam and governer marks line up. But dimple in drive gear (metal one) was not exactly straight up. Had to turn motor over a lil to get it so I could line up it with the C on fiber gear. (Is that normal)? Have tried different notches on fiber gear thinking maybe timing was off, No luck.
Starts fine and idles up fine, miss is more obvious at idle then high idle. Have turned air screw with no improvement. Marvel carb and morse mag.
Could timing be off a little still. Or mag maybe? Or carbon build up on top of valves maybe?
Not sure what to do next any thoughts or ideas would be great thanks! Sorry long post. Will try and post video.

[Adam Arc]

Just a thing f162 will do. You may never find it. Unless you rebuild the motor and document every spec to see whats out. If my 54 shorty ran like your 57, I would run it just to listen to it.

sent while goofing off at work

[dubl_t]

You know more than I do regarding the mag, but did you ever do a compression test or a vacuum test?

*I don't know offhand if there's a vacuum port on these engines, but I would think it could be done somehow.

[RyeGuy]

Yes compression was good. 120 if I remember correctly. And it has good vacuum until it "coughs". I ordered all new jets for carb and will try that today. Thanks for the replys

[Sparkie1957]

My 1966 has the same cough at times. Only at idle and running smooth and she will hiccup and the rain cap will clink then back to smooth running

[92dlxman]

i have the same little issue on my 163. low idle has an occasional "plut" every 5-10seconds. no real stumble it just sounds like one cylinder didn't do its job. mmmmmmmmmplutmmmmmmmmmmmplutmmmmm. high-idle is smooth as silk.

sounds silly but you may be able to isolate the miss to one wire with a light. . . .or just run it in the dark and look for a spark.

it sounds ignition related to me but a fuel issue is more likely I guess. I cant decide so I just leave it alone

[12V71]

My 1966 has the same cough at times. Only at idle and running smooth and she will hiccup and the rain cap will clink then back to smooth running

I think that's just the nature of the beast. Every 163 I have owned did that same thing. I think the Marvel carb was designed mostly for running at steady governed rpm rather than having periods of idling. Sometimes bumping the idle speed up helps.

[RyeGuy]

Yes if I bump the idle up a bit it seems to help a little. Another question, when adjusting air screw the only change I get is when its about all the way in. Once I back it off from almost seated and it cleans out I have no change in motor till its all the way out. Is that normal or maybe a part of the problem? Also I'm running rubber fuel line instead of copper. Is that ok?

[Pipeliner]

I'd be willing to bet every other machine you come across does this at idle. I have rebuilt the carburetor, new plugs, wires cleaned everything fuel related. Still does it. I really think it is a valve issue but not serious enough to spend anymore time looking.

[RyeGuy]

Valves? As in carbon build up? Should I pull head and see how they look?

[12V71]

I'd be willing to bet every other machine you come across does this at idle. I have rebuilt the carburetor, new plugs, wires cleaned everything fuel related. Still does it. I really think it is a valve issue but not serious enough to spend anymore time looking.

I don't think its a valve issue myself. I kind of suspect it has to do with the updraft carb. Maybe a small slug of condensed fuel at semi regular intervals? Throttle plate icing? As long as it runs good at welding speed, I never got too worried about that 10 second raincap "ting".

[Pipeliner]

Valves? As in carbon build up? Should I pull head and see how they look?

I'm sure there's a bit of carbon in there, but not likely the issue.

I don't think its a valve issue myself. I kind of suspect it has to do with the updraft carb. Maybe a small slug of condensed fuel at semi regular intervals? Throttle plate icing? As long as it runs good at welding speed, I never got too worried about that 10 second raincap "ting".

I'm with you on this. After chasing it to the point of frustration I have written it off and I only get worried if it isn't popping! It would be interesting for someone with a Zenith to chime in about this. Maybe CEP will see this - I think he runs Zenith on all his SA's.

[Sparkie1957]

Another issue I have is when the governor pulls my machine up to high speed it puffs black smoke. No smoke at idle or running at 1550 only on acceleration. No stumble, picks up fine and handles welding load. Is the power valve that comes out the bottom of the TSX adjustable like on old tractors? I think it is a tad rich.


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Steve
Lincoln IdealArc 250
Lincoln SA200 1966 Redface

[rexcormack]

The miss you described with all the work you've done is the texbook symptom of a valve sticking. Flatheads were more apt to do it because the guides didn't oil very well but even some overhead valve engines would do it. Every Farmall H and M I ever saw that had not been rebuilt did it.
The black smoke at throttle up is from the main jet adjustment being set too rich. Try turning it in an 1/8th of a turn and retrying your throttle up. If it gets to where it stumbles on throttle up you've gone to far!

[Sparkie1957]

Thanks Rex, will do. As for the valve sticking, will running Marvel Mystery Oil in it and some frequent oil changes help eliminate the issue?


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Steve
Lincoln IdealArc 250
Lincoln SA200 1966 Redface

[Sparkie1957]

I looked at my carb and it's only a plug in the bottom. I assume it's a fixed size jet. The old tractors had a T handle sticking out that you could adjust the power jet

[rexcormack]

The Marvel misery oil certainly won't hurt!
The overhead valve tractor engines were easy to pull the head and touch up the seats and guides, the flatheads not so much!
I have zero experience with the continental just all our old farm machinery when I was a kid so I
was hoping someone like DuaneB would chime in on the cough issue.
Someone may have gotten a little rough with cleaning the jets before you got it so replacing them may fix the black smoke on throttle up. If not and it is just a puff for a second or 2 I wouldn't worry about it.
But it would bother me too!

[RyeGuy]

Can one simply look in spark plug hole and check the valves? Or what's the proper way to check? Would that cause suck back thru muffler?

[Sparkie1957]

Thanks Rex, I agree it's not that bad, it just runs so sweet I want it perfect. I would rather it be a touch rich than lean. I suspect someone used a drill bit to clean that jet and oversized it a little now. I only did a quickie clean up on this carb when I got it from the farmer's barn so I might get a kit and try and locate a main jet for it


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Steve
Lincoln IdealArc 250
Lincoln SA200 1966 Redface

[weldermike]

Also check your air mixture screw, take it out and inspect it. Ive seen them scored in the past from over tightening back and forth while people were tuning them, and get a score mark around them from when fully seated and will never fully function right after that. My 66 redface purrs like a kitten, and who knows how many hrs are on it. Keep digging you'll get it, but check that mixture screw, so simple and always gets overlooked. I'm also thinking some lash in the magneto.

[Pipeliner]

I only did a quickie clean up on this carb when I got it from the farmer's barn so I might get a kit and try and locate a main jet for it.

If this gentleman doesn't have it for a Marvel Schebler, it probably no longer exists.

http://www.mcdonaldcarb.com/

[duaneb55]

Steve,

Many times a "quickie" clean up does very little if anything for a carb that's been sitting around with old gas in it for years. Get yourself a gallon can of chemical carburetor/parts cleaner that you soak the parts in from your local auto parts store. A 20-30 minute soak in a good chemical cleaner will break thru the shellac and other build up that may be plugging up one or more of the small passages in the carb body/cover. A plugged air bleed passage for example could be the cause of the black smoke upon initial rev up coming off low idle although a little may be considered normal.

On your idle mixture screw response, if the low idle speed is too high, it could be operating at the upper end of the idle circuit thus resulting in little change when adjusted. Also keep in mind on these carbs that the idle mixture screw is controlling idle air bleed so screwing the mixture in causes a richer mixture and out is leaner.

What Pipeliner said regarding McDonald Carburetor and Ignition. That's my "go to" for carb and mag parts.

[Sparkie1957]

Thanks Duane and Pipeliner,
My idle mixture screw is ok as it is responsive to adjustment and I was aware it adjusts backwards to normal carb screws, in for rich and out for lean. At some point I will pull the carb and give her a good soaking


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Steve
Lincoln IdealArc 250
Lincoln SA200 1966 Redface

[RyeGuy]

Thanks Fellas, I turned idle down a bit and was able to adjust air screw and got it to run a little bit smoother. Still not purrin like a kitten and I won't stop till it does. 125-135 compression on all cylinders. Next step I'll take mag in and have tested, and see if I can't find a carb to swap. Sparkie nice high jack lol hope you get yours running rite.
Could this new ethonal gas be giving these old machine troubles?

[Pipeliner]

Could this new ethonal gas be giving these old machine troubles?

I use e-free and it makes no difference.