Marvel carb help needed

Southtowns27 · Jul 8, 2015

Hoping someone has an idea for me here... Long story short, I got an old Lincoln SA200 "pipeliner" welding machine for free. It's driven by a Continental F163. It's got a Marvel Schebler TSX514 carb on it. The thing hadn't run for years so I pulled the carb to clean it out, it was full of rust and crap. I didn't put a rebuild kit in it at this time since I didn't know if the machine even ran or not and didn't want to start spending money. Anyway, put it all back together and got it running. It ran perfect at speed and idle, but when I would shut it down it would just pour gas out the carb..presumably a bad needle and seat. So, I bought a kit for it, new float, needle and seat, gaskets, etc. I cleaned the thing so it was spotless, put all the new parts in it, and now it won't idle unless I pull the choke about half way out. It's unresponsive to the idle mixture screw. Runs fine at speed though. I've tried raising the float level, taking it apart and blowing air through all the passages... I'm really kinda lost. Does anyone have any working knowledge of how the idle circuit in this thing works? Anything I'm obviously missing?

Switchflicker · Jul 8, 2015

My Marvel carb did the same thing on my 2N. Turns out there was an air leak between the carb and the manifold. Loose bolt on one side. Good luck

JMOR · Jul 8, 2015

(quoted from post at 09:51:04 07/08/15) Hoping someone has an idea for me here... Long story short, I got an old Lincoln SA200 "pipeliner" welding machine for free. It's driven by a Continental F163. It's got a Marvel Schebler TSX514 carb on it. The thing hadn't run for years so I pulled the carb to clean it out, it was full of rust and crap. I didn't put a rebuild kit in it at this time since I didn't know if the machine even ran or not and didn't want to start spending money. Anyway, put it all back together and got it running. It ran perfect at speed and idle, but when I would shut it down it would just pour gas out the carb..presumably a bad needle and seat. So, I bought a kit for it, new float, needle and seat, gaskets, etc. I cleaned the thing so it was spotless, put all the new parts in it, and now it won't idle unless I pull the choke about half way out. It's unresponsive to the idle mixture screw. Runs fine at speed though. I've tried raising the float level, taking it apart and blowing air through all the passages... I'm really kinda lost. Does anyone have any working knowledge of how the idle circuit in this thing works? Anything I'm obviously missing?

on't know the 514, so it may be very different from the 33 & 241 on old "N" tractors, but maybe this will be of some help.....then maybe not?

On the 33 & 241, the Idle adj screw works backward from the Power adj screw, in that closing it down shuts off idle air (richer) and backing it out allows more idle air into the idle fuel stream (leaner).

Southtowns27 · Jul 8, 2015

That pic is actually pretty close. And now that you mention it, the thing does want to try to run better with the idle screw turned all the way in. But, the picture shows fuel passing by the idle screw, not air. So I guess I'm still a bit lost... I'm fairly certain that I don't have any vacuum leaks since I already tried spraying carb cleaner around all the gaskets while it was running.

Edit: I just found another diagram that shows exactly how the idle mixture screw works..I understand that now. It's so simple...there's just got to be a piece of junk stuck in a passage someplace..

Determined · Jul 8, 2015

Given that it ran good before and you are quite sure everything is clean, I would check for a vacuum leak.
You said that it runs decent with the choke partially on.
This typically indicates:

- Vacuum leak
- Plugged passage
- Incorrect float setting
-Throttle shaft/bushings worn

A tell tale of a restricted fuel filter is little to no governor response at full load.

Have you checked the valves, a tight valve will rob you of intake vacuum.

Southtowns27 · Jul 8, 2015

Well, I got it. A chunk of rust got into the idle passage in the lower body of the carb. No fuel could get up to the top where the adjustment screw is. I had to really stab away at it with my tip cleaners to get it dislodged.

W_B · Jul 8, 2015

My experience with both of my Ns is throttle shaft air leakage can have a big effect and get it clean, clean, clean. Be sure when you adjust the idle that you are really on slow idle, too fast and the idle mixture does nothing.

Geo-TH,In · Jul 8, 2015

The fuel for idle goes past main jet, the larger jet. The idle circuit adjustment is
backwards of the main jet. Turn main jet in to lean out. Turn idle jet in and it should
get richer. That's how it works on my Jubilee. Check to make sure if you Crank main jet
in all the way in, it will starve engine for fuel and die. A friend rebuilt his carb and
put washer on the main jet out of the kit and it prevented the main jet from going in
far enough, too rich of mix.

Marvel carb help needed

Southtowns27

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Switchflicker

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JMOR

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Southtowns27

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Determined

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Southtowns27

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W_B

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Geo-TH,In

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