Started running Rough

My 51 had been running good. After a short break I restarted it and it was running rough. Pulling the choke definitely smoothed it out. I'm leaning towards a fowled carb but wanted to ask for suggestions incase I'm over looking the
obvious. I did pull the plugs as it's been a while and they all look great and have strong spark, point gap is still at .025.
Second question, I have a spare carb that I was going to refresh and install. The sides of the float look caved in. Is this float usable?
Thanks all!!!

That is not the picture I was uploading. Thats not even a picture of mine.

Two tries and other people pictures are being uploaded.

Any suggestions why pulling the choke smooths out the engine would be appreciated.

Pulling out the choke gives you a richer mixture. So, you could have either a fuel or spark problem.

A carb out of adjustment will also cause this problem; set the main jet at 1-1/2 turns out & leave it alone.

A dirty carb can cause the problem as well; start by cleaning the fuel screens. (see tips 45 & 56)

Dirty/old gas, or water in the gas can cause this problem.

Restricted fuel flow can cause this problem; remove the bolt at the bottom of the carb & check for flow. The flow should fill a pint jar in under 2 minutes.

On my 1950 frontmount, needing choke to run is the first sign that the points need adjusting/replacing.

A vacuum leak can do the same thing. Get a hand propane torch and carefully spray it (unlit of course) around the intake manifold at the carb to manifold interface & the manifold to block gasket of the tractor while it is running. Or, you can use carb cleaner or WD40. If it speeds up, you found the leak. Sometimes (rarely) manifolds crack or get rust holes.

Lastly, when all else fails, you could have an air leak around the carb metering section. The likely suspects are leaky throttle shaft seals and/or a worn throttle shaft. Or, just a real dirty carb w/ clogged passages.

Bottom line: Probably 98% of "needs choke to run" problems are fuel related, but do not rule out ignition problems, contrary to what others may tell you. I’ve had that very same problem before w/ a rebuilt carb, fresh fuel & good flow & a tight manifold.......and it was a spark problem. But, that was unusual. Just check the likely fuel problems first.

Hi Bruce,

Thanks for great reply and I apologize for delay response, it was a wet week here and I was unable to give the tractor a decent workout. I went through the ignition and was satisfied there were no issues there. I did as you suggested and found no intake/vacuum leaks. Fuel flow out of the bowl drain was in excess of 1/2 a pint a minute. I disassemble the carb, it had been 15 years since last rebuild but looked spotless inside. I used cleaned and compressed air on all the jets and ports, reassemble and installed, it's running better than it has in quite some time. Float adjustment did look good upon disassembly but the appearance of the float bothered me and I swapped it with one from my spare. I'm going to attempt to attach a pic again, any thoughts on why the sides are collapsed? I don't have much hands on with the 8N carbs, does it look like the venturi is upside down in this picture? I know I correctly reinstalled it.