All Small Six warm engine stops running with choke fully open

This relates to all small sixes

shreqshack

Well-known member
I need some help troubleshooting. The engine (200 6 cyl) runs best (doesn't stall out) with the choke open about 50% with the engine at full operating temperature. However, the engine is super sensitive; it doesn't run well unless I set manual choke "just right." If I try to open it up a little bit more the engine stalls out; wont stay running. I have a 1965 mustang (autolite 1100 with aftermarket manual choke) and the original load-o-matic distributor. The "auto choke" on the carb has been disabled in favor of the manual choke lever (installed by prior owner). I rebuilt the carburetor about 4 months ago.

What should I be looking for? Where do I start? I bought a vacuum gauge to help resolve this.
 
Personally, I would start with making sure the engine's tune was as close to the car's engine sticker as I could get it. my car is a bit newer, but there is a sticker on the underside of the hood that gives FoMoCo's recommendations for the engine. once I verified those, I would check the filters (air filter/fuel filter). if timing, idle speed, spark plug gap, and the filters are all good, then I would dig a bit deeper by checking vac lines. my car uses the Motocraft 1946, so I am not overly familiar with the autolite 1100. but I am assuming this started after your rebuild; did you make sure the fuel float was bent into place properly? did the check-ball's weight get put back into place? was the idle mixture screw able to fully seat before you started backing it back out? all questions I would start looking at after verifying the stuff that doesn't make me tear the carb down again.
 
Thanks so much ... I will start with what you suggested. The car was not running prior to the rebuild of the carburetor. It had sat for 20 years. The car is running now but obviously needs some adjustments. I was careful when I did the rebuild but doesn’t mean that I got it all assembled perfectly.
I will go back through it and reinspect
 
if it wasn't running before the rebuild, verify your fuel pump is working, and there isn't anything plugging or restricting the fuel hoses/lines. a weak fuel pump sometimes doesn't deliver enough to the bowl, and the choke could hide it. does the engine flood out, or lean out with the choke fully off? (butterfly open)
 
just added this to the RBS Q: do a full ignition tune 1st. Many carb issues (appearence) R actually ign ones. Do that to rule it out, all ways, 1st. Restoring a car is same, altho here it may not fix ur's. Something is saying "I need a richer mixture." from the engine. Vac leak is a suspect...
 
just added this to the RBS Q: do a full ignition tune 1st. Many carb issues (appearence) R actually ign ones. Do that to rule it out, all ways, 1st. Restoring a car is same, altho here it may not fix ur's. Something is saying "I need a richer mixture." from the engine. Vac leak is a suspect...
Chad...thanks for your help. Quick question for you....When you say "full ignition tune" are you suggesting that I inspect everything that that involves a basic tune up? I would check the points, rotor, distributor cap, plugs wires, engine timing, idle speed and carb adjustments?
 
Do U havea hanyes or Chilton's? It's standard proceedure,
uncle bubs posted upa great ck list, C if I can find it:

Here are the Stock 1962 144 or 170 Tune up specs
Distribitor rotates CW firing order is 153624
Autolite BF-82 plugs gaped at .034.
Basic Points setting gapping them at .025 but for the very best performance your looking for a Dwell setting of 37 Degrees.
Base timing is set to 4 Degrees BTDC for a Standard ( Stick) trans and 12 Degrees BTDC for a Automatic trans.
Idle RPM is 550 to 600 RPM for a Standard Trans and 500 to 525 RPM with an Auto Trans in Drive, parking brake set,
Fuel pressure is 4.5 PSI

To get most accurate tune up with a orginal point ignition always use of a tach / dwell meter, and also a timing light. This is the procedure I have used for decades to quickly do a precision tune up.

A good tune up follows this order of work.
1. Set the plug gap to .034
2. Set the points basic setting to .025 after its running set the Dwell Angel to factory spec of 37 degrees.
3. Now you need to set the timing to the 6 degrees (with stick Trans) or 12 degrees (Auto Trans) base timing vacuum line disconnected and plugged. You can also try more base timing to as much as 16 degrees but if there is any hint of pinging when you try driving it up a slight grade then back it off until it stops. Reinstall the vaccum line to the Distribitor after setting the base timing.
4. With engine warmed up good, the intake and exhaust valve lash is set to .016 hot on those engines with solid lifters 1960 to 1962 and also were still used in some later years of Econolines and Ranchero's)
5. With the engine fully warmed up good and also check that the choke blade is fully open too. Set the Idle mixture to its Lean Best Idle. ie set to highest idle RPM then turn the mixture screw in 1/4 turn to lean it. See Addistional Notes below.
6. Set the curb idle speed to 550 to 600 RPM if standard Trans. Set idle RPM's to 500 to 525 RPM with an Auto trans in drive parking brake set, wheels chocked with block of wood, or you can have someone set in it and hold the brakes.
7. Repeat 5. & 6. To see if it improves anymore. When properly tuned these engines (when warmed up) will restart without even touching the gas pedal.

Addistional Notes
You might also test your coils output with the volt / ohm meter to see that it's within spec. Or you can do it by watching the spark color (a Bright Blue) and the lenght it can jump to cap terminal (from 1/2 inch or more).

While doing the tune up settings to the carb mixture and curb idle setting the engine needs everything installed and hooked up just as it will be operated! This includes having the Air Cleaner with a clean air filter installed and the PCV hooked up if your engine has one. If you want to use a Vacuum gauge then hook that up to the Intake Log below the Carb you would be looking for about a steady 17 inches of vacuum at idle RPM. Good luck in your tuning. A good upgrade for these engines is a Pertronix Ignitor and its matching coil, the engine still looks stock but gives you a hotter spark.
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yup, right offa da maestro's key bd
I'd just swap the last line to say: Use the DSII components ifa post '64 block & able to drop SCV/LOM carb/dizzy ('68+)
 
I need some help troubleshooting. The engine (200 6 cyl) runs best (doesn't stall out) with the choke open about 50% with the engine at full operating temperature. However, the engine is super sensitive; it doesn't run well unless I set manual choke "just right." If I try to open it up a little bit more the engine stalls out; wont stay running. I have a 1965 mustang (autolite 1100 with aftermarket manual choke) and the original load-o-matic distributor. The "auto choke" on the carb has been disabled in favor of the manual choke lever (installed by prior owner). I rebuilt the carburetor about 4 months ago.

What should I be looking for? Where do I start? I bought a vacuum gauge to help resolve this.
After checking out the basic tune up items above how dose it run? If you still need to add closeing the choke part way to keep it runing then start looking for Vacuum leaks carb base gaskets there are more than one one some engines, all the vacuum lines, a very comman place on an old well used carb is the throdle shaft on the linkage side can get worn and get excessive amount of slop due to the linkage pulling and pushing with the pressure of the return spring acting on the throdle shaft to. There are busing kits made that can repair / fix this extra clearance between the throdle shaft and Carb's base bringing it back into factory specs again. Good luck
 
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