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Old 09-13-2020, 05:26 PM   #10
5Tractorguy
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Join Date: May 2015
Location: Central Massachusetts
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Re: 350 has bad misfire/shudder over 2000RPM

Quote:
Originally Posted by geezer#99 View Post
If the clip on the needle is on wrong or not used it can cause flooding like that.

Info in here on that.

http://www.crankshaftcoalition.com/w...4MV_carburetor
Thanks Geezer! There's a ton of good info on that page...


Quote:
Originally Posted by Corts60 View Post
Vacuum advance is working but does mechanical advance move freely? When your foot is into it, no vacuum will be there to advance so it will be relying on the weights. Because you say it is only over 2K RPM under load, this makes me think it is not advancing. But check your fuel system first like everyone else stated.
The mechanical does move well, though I should check it again. The guts were swapped in from another 350 distributor because the original weights and shaft were very badly worn (see pic). Assembled nice with the good used parts and moved as it should. Worth another look though just to be sure.


-So, fuel pump is good.
-Turns out the carburetor wasn't bolted down tightly, never re-checked after I installed and ran it.
-No vacuum leaks around the manifold or carb base (after tightened)
-Set the carb idle screws by the book with a tach and it sounds much smoother at idle and starts better

After that, it still misfired when shifting up, even going down hill. So I pulled a plug wire and hooked up one of those inline spark testers. When running it jumped the 3/16 gap, but the spark was orange at best. Leaning towards weak spark now... Never replaced the coil when I rebuilt the distributor, did everything but... dang! Going to pick one up tomorrow.



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