Autolite 1100 Mixture Adjustment

[Route--66--]

HELP!
How do you actually adjust the mixture on the Autolite 1100 ?? .. in cars I had years ago (here in England) there was always a screw or something on the carb that you screwed in to weaken or out to richen the mixture.

Is the 1100 different to that??.. do I have to change the jet or something or is there some way of adjusting??

Please see pic of my plugs - there are 3 in the pic .. I think they were numbers 1,2 and 5.
am not sure if the engine is running really rich as the plugs are black or if I'm getting some oil past the rings .. but I don't notice any oil depletion at all and have never seen any blue smoke out the back at all ... so am confused?!
My mate following me said I put out a small puff of black smoke when I floored it a few months back which also makes me think it's running rich..

Sparkplugs pic: http://www.classiques.org.uk/mustang/plugs125.jpg (pic is 1.6mb so may take a few seconds to download full image) plugs are quite new (1200 miles maybe..)

CAN ANYONE HELP ?!?!

MANY thanks in advance!!
From 'no-idea about-Autolite-carbs-Limey' !!

 

[Route--66--]

Your plugs don't look real bad but it shows signs of being rich on those two.


Carb tuning

Yes for most all carbs, the idle mixture screw (slotted, knurled, spring under it) and turning it is (IN=LEANER) and (OUT = RICHER). Before you even try setting the carb always set the points (if you have them still) to proper dwell and timing to spec.’s. All those tune up parts i.e. points, cap, rotor, wires etc. need to be in good condition

During a carb rebuild the screw is turned in all the way (GENTLY!!), then back it out about 1.5 - 2 turns. That should run well enough to get it to start. Skip this part on running car that you are just tuning up. The "old timer" method can get you within 10% of what you could do with a gas meter and all that nice stuff. Next get it warmed up good.

Once warm; make sure the choke is fully open. If it’s an auto type and not open, than loosen the screws around the black cover and turn it LEAN until it is. This also means that the warm-up fast-idle setting will now have no effect. Choke adjustment will be put off till last

Find the idle-stop screw; set the idle to as low as it will run reasonably. Then tweak the idle mixture screw for the fastest idle speed. If the idle is now "too fast", back off the idle-stop screw to slow it down, and reset until you get it at the highest idle. (An alternative method is to use a vacuum gauge, and adjust idle mixture for highest vacuum.) As a sanity check, the idle mixture screw should be still around 1.5 - 2 turns. If it's crazy far in or out, there's a problem in the carb will need cleaning and rebuild etc.

Then, turn the mixture screw in (LEAN) a tiny bit until you hear the idle speed drop "a bit", 50 rpm or so. It's about the smallest noticeable speed drop. (Alternatively, until vacuum drops 1 - 2 In Hg). That's called "lean idle drop". It's good for emissions and leaner idle is better than richer here. Than reset the idle RPM to spec in drive with parking brake set for an auto trans. With a stock or near stock motor it ought to be very smooth.

Now you will need to wait for the motor to cool down, set the thermostat to 1 or 2 LEAN. Open the throttle all the way and let go. The choke should be partially or mostly closed (depending on temp were you are); the fast idle screw should be resting on the stepped cam. It can be hard to see. You can eyeball its operation by opening and closing the choke with your finger and see it step onto and off the cam. Start the car. Without touching the throttle, adjust the fast-idle screw to the "fast idle spec setting ". Once it warms up, opening the throttle should allow the (now hot) thermostat to pull off the choke (open) and also off the fast idle step. That's it you’re done.

 

[Route--66--]

Thanks yet again Bubba!

first re the ignition side - I have pertronix ignition, standard coil and newish spark plugs (about 1200 miles / 6 months old)

ahhh.. so are you saying that the idle mixture screw (on pass side with spring under) is the main mixture adjustment ?...

If so I have already adjusted that a while back .. turned it clockwise until engine started to stumble, then anticlockwise til same happened then set it in between the two.
So the result of that is what u see in the pics.
Went for a run today and set it slightly too lean (turned screw clockwise until engine juuust started to stumble) so maybe will see how that goes.

I wondered if the black slight wetness might have been the plugs starting to oil up although couldn't understand why as the engine runs well and doesn't burn any oil ..
although exhaust I notice does seem to be furred up all black inside . .. indicating too rich ..

The carb seems to work really well apart from that - engine revs instantly and well when I jab the accelerator, starts literally in under a second when cold and 2-3 seconds of cranking when hot.

so... not sure .. if I have set the carb pretty close to what it should be am wondering if there's some other issue .. ..? .. :

Thanks yet again! .. will pop in with the wife and buy you a drink and meal perhaps next time I'm on a usa roadtrip !!

Cheers!

 

[bubba22349]

You are probably very close on the mixture screw try turning it in (lean) until it just starts to stumble than back out too where it smoothes out again than stop your good to go. For this area SoCal warm most of the time I run a range colder plug (for mostly freeway driving) I like the Autolites or Motorcraft plugs seam to run better and last longer. I also use best quality points sets like NAPA and Cap and rotor with the brass posts, top quality plug wire sets too. Your float might be a tad higher than it should be. A good indication of a perfect tune is when its warmed up (and also in warm weather) you don’t need to touch the gas pedal on cranking it on a restart it will fire and run in very few cranks. Should be a bit faster when warm over a cold start.

 

[Route--66--]

Hi again
After weakening mixture I took it out for a run on Sunday ..about 40 miles or so ..
Took out plugs tonight for a nose and they look much better on the whole.
They are in the picture in the same cylinder order - i.e. number 1 on the far left, number 6 on the right:
http://www.classiques.org.uk/mustang/plugs12jan11.jpg

So.. somewhere in the middle of cold dark England this evening I was quite happy!
Looks like your thoughts that there wasn't any oil getting through was correct.

I've cleaned up the plugs and will see how they go..

Assume that numbers 1 and 6 look a lot weaker just due to inefficiencies of the intake manifold.

Had a look inside the bores at the top of the pistons while the plugs were out - they looked really quite black-furred up no doubt due to the over-rich mixture setting..

Interesting about your starting - will give that hot start method a try!

THANKS AGAIN!