At higher speeds, the engine vacuum drops which causes the power
valveto open and allow more fuel to flow.
Watch a video about the power valve.
Do not remove the
power valve assembly when rebuilding, but it does need to be free to
easily move up and down. For sticky power valves spray liberally with
silicon spray lubricant and work it up and down until it is free. Worst
case is you will have to remove the clean out plug on the top of the
carburetor so that you can get at the cylinder for cleaning. You will
need a new clean out plug, or patch up the old plug with JB weld (don't
get any inside). A surge at high speeds (steady throttle) might
indicate a power valve
problem. Change the power valve timing to open sooner (at less throttle
opening) by adding additional calibrating shims, on power valve rod
(see illustration above). If less than 4 shims found on rod, add 4
shims; if more than 4 shims found on rod, add fewer number. Total
number of shims on rod must not exceed 8. These shims are not produced
and you only want to take the power valve apart as a last resort.
Autolite 1100 Main Jet
This is where the
Autolite 1100 main jet resides. Due to the difference in gasoline, the
jet size that was originally installed on the 1100 isn't that relevant
anymore. Be sure you are using the correct jet size, otherwise you
chance ruining your engine. Test your main jet
by running your vehicle for 20 minutes at a sustained speed. Pull a
spark plug and look at the color. Gray is perfect. White means you are
too lean and need to move up one size.
Black is too much fuel and you need to move down one size. Do this one
size at a time until you get a good gray colored plug. This test is
only valid when your engine and electrical system are good condition.
Autolite 1100 Main Jet Sizes - Note: These sizes
do not take into
account today's gasoline blends. It takes more fuel to run the same
mile so error to the bigger sizes. For elevations 5,000 ft and above
reduce the size by .02. Use the procedure above to determine if you
have the correct size in your situation.
Accelerator pump gauge: 3/16"
Initial Idle Mixture Adjustment: 7-8 1/2 turns
Float Setting: 1" gasket surface to float crown
Dashpot: 3 1/2 turns in from screw just touching
MANUAL CHOKE DRILL SIZES
223, 262 Engine
1966 Rough Idle & Poor Fuel
This condition may be caused by the fuel bowl vent valve being out of
adjustment. Check and adjust the vent valve each time the carburetor
idle speed adjustment is made.
These are no longer available, but you can make your own. Use a 3/16"
aluminum rod, cut 9/16" long. File the end a bit as pictured. Weight
will end up being about 1 gram.
video about On The Bench Adjustments
Watch a video about rebuilding the Autolite 1100 carburetor. Part 1 -
I seem to have a problem with my carb that I rebuilt recently. It is a
C8PF-D on my 1963,170 cu in Falcon with auto trans. Its a manual choke
and has the spark control system and a diaphram on each side. We
adjusted the mixture screw till it ran nice and took it for a small
drive. Upon returning it would not idle hardly and was running very
rough. We adjusted the mixture screw again and it started runnning
properly agian. The next drive we took it ran great, but when we
arrived home the same rough running and no idle was present agian. It
acually died on us instead of idling. My question is if the mixture
screw is backing itself off due to vibrations etc.? Could the screw or
spring be worn out or could it be the carb hole and threads worn out? I
hope you have run across this before and can point me in the right
direction. I thought about loctite to hold it, or maybe a new
spring and screw.
1st off don't use anything on the threads. That would probably ruin the
carburetor. It does seem the screws are moving from vibration. I would
replace the idle mixture screw and spring.
Watch a video about the Autolite 1100 Flooding Troubleshooting