All Small Six Autolite 1100 part throttle acceleration/cruise miss

[Rheacox]

I'm trying to diagnose a problem with my '63 Falcon with the 144 and autolite 1100, full engine rebuild 1,000 miles ago. It has a miss/stumble at part throttle either light acceleration or cruise, 1st, 2nd or 3rd around 2500rpm+. It idles nice and if I put my foot to the floor it smooths right out and pulls as well as a 144 can pull. It's a slightly intermittent problem, happens maybe 80% of the time.

I just put a carb kit in it and cleaned it out due to rust in the old tank. The miss was there before and it's still there after the cleaning. I also changed the main jet while I was in there from a 55 to a 53 which is what the manual says is correct, doesn't seem to have made much difference, if anything it's worse but again it does pull well at WOT. The bowl gasket is also weeping for some reason, I set the float at 1" and the needle is holding pressure (get a good spray loosening the line to the carb). Something is off with this carb and I'm just not finding it. I changed the filter in the pump and the prefilter I installed yesterday too.

It does still have the stock LOM distributor and I rebuilt that earlier this year. I checked the dwell and it's within spec and the plugs look on the dark side of tan, not bad. I'm doubting it's a spark issue but it's still possible.

 

[chad]

some are there and never perfect, of course we shoot for perfection but become satisfied w/the results. Here we have a great many things done (see quote in my sig below) but recommend a start at the beginning as solution for that...a full ignition 'tune' from start to finish to rule that out. Here's a 'stickie' from our resources here, most likely Mr bubba's handy-wrk:

Here are the Stock 1962 144 or 170 Tune up specs
Distributor rotates CW firing order is 153624
Automate 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 original 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 it driving it up a slight grade then back it off until it stops. Reinstall the vacuum line to the Distributor after setting the base timing.
4. With engine warmed up good, the intake and exhaust valve lash is set to .016 hot.
5. With warmed up good and 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 Additional 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.

Additional 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 length 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 engine still looks stock but gives you a hotter spark.
- -
done here? go onto the 'carb' tune up, again - start to finish. Then? - A speck in the needle'n seat, clogged fuel filter, etc, etc...

 

[B RON CO]

Hi, I would set the ignition timing to @ 12* BTDC, and I would check the vacuum advance with a timing light to make sure the advance is working. If you don't have a timing light with an adjustable scale you can open the throttle and the timing mark should disappear under the water pump. Good luck

 

[Rheacox]

Just finished a thorough tune up, got out the timing light, vacuum gauge, and sears auto analyzer. Timing is set to 12*, idle is at 600, and the vac gauge reads a pretty steady 17inHg at idle. I also reset the float height, I was using the factory manual spec of 1" but thats for the plastic float, reset it to 1-3/32" with the brass float.

It idles nice, no stumble when when I stab the gas and once it's warm it starts if I so much as look at the key. Still have to road test it but it definitely won't be any worse than it was.

 

[Rheacox]

Hi, I would set the ignition timing to @ 12* BTDC, and I would check the vacuum advance with a timing light to make sure the advance is working. If you don't have a timing light with an adjustable scale you can open the throttle and the timing mark should disappear under the water pump. Good luck

It's definitely working, no idea what the advance goes up to but it is buried under the water pump when the revs come up.

 

[wsa111]

Still, you should run an A/F test with a wideband tester just to make sure you A/F ratio is in the 14.3-14.9 area especially after a main jet change.

 

[chad]

idle screw'n choke?

 

[Rheacox]

Just took it out to run some errands, ran like a dog. Very little power. I had the dwell at the upper end of the spec, dropped it to 35* and gave it another ~4* of timing up to 16*. Performance is back to where it was, but the stumble/miss is still there. It is also there under WOT but it's hard to notice.

Something is still off in the carb. I'm thinking it might be time for a new one, I've been in it a few times now, it's got 75k miles on it and sat for 40ish years untouched. It's also still weeping at the gasket so I'm guessing the halves are warped. Heard mixed reviews about the Chinese eBay 1100's but for the price I might give one a shot.

 

[chad]

some have an issue @ where the butterfly's rod (brass?) wears away the alu housing of the carb (in the 100K mi range?). There's a rebush kit on net but I'd try the spray test B4 carb removal. Don't compair to a modern mpfi car. These havea lill something in most cases, will not B exactly like ur honda/toyota.

 

[Rheacox]

some have an issue @ where the butterfly's rod (brass?) wears away the alu housing of the carb (in the 100K mi range?). There's a rebush kit on net but I'd try the spray test B4 carb removal. Don't compair to a modern mpfi car. These havea lill something in most cases, will not B exactly like ur honda/toyota.

I understand that but this stumble/miss ain't normal. It should be at least as smooth as my Model A (maybe it needs an updraft )

Not much play in the throttle shaft but there is some, I'll try the spray test.

 

[chad]

Just 1 more thing 1st. U did post #2 above? Now for:

1. Set the Plug gap to .044 or .045

2. Set your timing to 10 to 12 degrees BTDC, or your custom setting.

3. With the engine now warmed up to operating temp and check that the choke is fully open. Set idle mixture to lean best idle. This done by first setting it to the highest Idle RPM using a Tach / Dwell meter and then you turn the mixture screw in 1/4 turn (leaner). These above settings (and also next below) should be done with the Air Cleaner installed just as the car is operated or driven on the street.

4. Last set the Curb idle to 500 to 575 RPM for manual trans, 550 to 600 RPM for auto trans in drive with parking brake set, this will usually be 50 to 100 RPM higher when trans is in Neutral or Park.

5. Repeat 3 & 4 to see if there is any more improvement.

Remember that when you change the base ignition timing setting you will also need to retune the carb settings again.


To get an idea on the timing chains condition turn the engine in its normal rotation stoping when the crankshafts Dampener is on TDC Mark. Next make a chock mark on the Distributors rotor position now turn the engine backwards until the rotor just starts to move and stop and Mark it there and on the crankshaft Damper. The difference from TDC Mark to the second mark is a good indication of the amount of the timing chain stretch or slop.

 

[wsa111]

Just 1 more thing 1st. U did post #2 above? Now for:

1. Set the Plug gap to .044 or .045

2. Set your timing to 10 to 12 degrees BTDC, or your custom setting.

3. With the engine now warmed up to operating temp and check that the choke is fully open. Set idle mixture to lean best idle. This done by first setting it to the highest Idle RPM using a Tach / Dwell meter and then you turn the mixture screw in 1/4 turn (leaner). These above settings (and also next below) should be done with the Air Cleaner installed just as the car is operated or driven on the street.

4. Last set the Curb idle to 500 to 575 RPM for manual trans, 550 to 600 RPM for auto trans in drive with parking brake set, this will usually be 50 to 100 RPM higher when trans is in Neutral or Park.

5. Repeat 3 & 4 to see if there is any more improvement.

Remember that when you change the base ignition timing setting you will also need to retune the carb settings again.


To get an idea on the timing chains condition turn the engine in its normal rotation stoping when the crankshafts Dampener is on TDC Mark. Next make a chock mark on the Distributors rotor position now turn the engine backwards until the rotor just starts to move and stop and Mark it there and on the crankshaft Damper. The difference from TDC Mark to the second mark is a good indication of the amount of the timing chain stretch or slop.

Your plug gap with a stock ignition should be closer to .035"-.038"
Ohm all your plug wires including the coil wire. Should be no more than 400 ohms per foot. Richen your main jet & make sure your accerator pump linkage is set for maximum shot.

 

[Rheacox]

Did the spray test around the throttle shaft and it just about killed it at idle. Looks like I should probably bush it. Still doesn't explain the weeping gasket though.

Also, I switched back to the 55 main jet and it's considerably better... really thought I was doing the right thing going off the factory manual. The stumble is still there but it's very drive-able now. The 53 jet might be just fine if the throttle shaft leak weren't leaning out the mix though.

 

[Rheacox]

Plug wires checked good, and plug gaps were all at .035 as well.

 

[bubba22349]

Did the spray test around the throttle shaft and it just about killed it at idle. Looks like I should probably bush it. Still doesn't explain the weeping gasket though.

Also, I switched back to the 55 main jet and it's considerably better... really thought I was doing the right thing going off the factory manual. The stumble is still there but it's very drive-able now. The 53 jet might be just fine if the throttle shaft leak weren't leaning out the mix though.

Congrats on finding the problem, many don't seem to be able to find this very common cause of poor engine performance. The carb base hole being worn out on the throdle arm side is to be expected after all their years of service, and doing the bushing replacement is a good fix to restore the carb back to good health. For your weapping gasket over tightening of the top cover screws over the years causes this type distortion. I have had good luck in fixing many of them by setting the Carb's top cover on a nice flat surface and then very gently and slowly tapping the cover flange a little at a time with a punch (or some square bar stock) to get it back flat again some small C Clamps could also work but again be very gentil and go slow so as not crack the flange. Best of luck

 

[chad]

old DA discs sit on my lift (a known flat surface, discs adhear to the pad w/tacky stuff). B 4 they get too grungy (not leave a good result in the painting process) I remove/smack up there. The fine is good for a rub of the carb housing IF it's just off a lill which can B told by (again) putting ona flat surface & getting the face dwn there to see how much light shines thry frm a flash lght on the surface behind...

BTW: what did U spray - I use the cheepest in shop - brake clean & it races, the opposite...fella here used a cigar (watched the smoke direction).

 

[Rheacox]

I've got to check the surfaces to see how warped they are, didn't look like they were leaking when I got home from work. I think I have some old panes of glass I can check them on.

I sprayed some carb clean, the shaft must be sloppier than I thought. Acted almost like I sprayed it down the throat. Is there enough meat to drill out to 3/8"? I can use regular bushing stock from McMaster if so.

 

[chad]

just have the ID match the rod OD right?

Throttle Shaft Bushing Repair Kit Carburetor 3/8 Piloted Reamer 4 Bushings NEW | eBay

Designed for 3/8 throttle shaft repair. 3/8 id, 7/16 od; 1/2 in length. This tool is designed for use on Quadrajet and Holley Throttle Bodies. It is not designed to ream out existing brass or bronze bushings.

www.ebay.com

 

[chad]

that's just 1 co I stumbeled onto today while searchin 4 an example 4 ya...

 

[bubba22349]

I've got to check the surfaces to see how warped they are, didn't look like they were leaking when I got home from work. I think I have some old panes of glass I can check them on.

I sprayed some carb clean, the shaft must be sloppier than I thought. Acted almost like I sprayed it down the throat. Is there enough meat to drill out to 3/8"? I can use regular bushing stock from McMaster if so.

Yes X2, there is plenty of material to be able to ream out the throdle shaft hole for the over size bushing this was a common repair by the old time carb rebuilders. Site member FTF French Town Flyer did a great wirte up of the this process that he uses on his Autolite / Motorcraft 2V Carb's (Technique is the same for the 1V Carb's and many others) in the below link that link as has another link that goes into the details and has lots of pictures too. Best of luck

THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

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