Autolite 1100/1101 Float Bowl Relations

[1966Mustang]

Hello,

So, I've been playing around with my float and jets, trying to get this thing to run and idle right. It's had it's gremlins, but they're on the run.

I went through my shop manual, checking everything as far as specs and settings and all that. I've determined that the shop manual is a good starting point (or not). I say this because the relationships in the fuel bowl have to be different with aftermarket rebuild kits and jets. Unless you've got a stock of NOS 1960's parts, whatever is now in your carb is close but not exact.

Sure, I acknowledge I might be misguided here. But, I'm tuning it in the right direction. Please let me know if I'm on the wrong track!!

There's multiple things going on with my car too. Carb was switched from a Holley 1940 back to a 1101. Distributor was changed to a DUI. Engine was rebuilt from the ground up. Different Cam, valves, etc etc.

Here's the main question I'm trying to figure out because it's a pain to pull the top off the carb when it's hot. So, tomorrow before I start it up, please have an answer for this

The Question is...

When the engine is at operating temp, I'm having a hell of a time getting it to idle smoothly. It idles smooth when warming up on choke.

What RPM should this thing be running around when cold?

I've checked for possible vacuum leaks.

I haven't been able to get it to idle near 600-700 to set my initial advance.

I'm suspecting float level setting. I started at the manual's recommended 1.09. That sucked too much fuel at idle I think. I set the float higher. This was better, but I only went up a 32nd or so. I was able to get it to idle down a bit, but still not smooth. When I look down the carb hole I can see fuel rain dropping in, but not as much with the 1.09 setting. I am using a 66 jet. I have 62 and 64 jets to try also.

And - I did the 1/16 drill bit setting of the fast idle and carb plate and throttle plate. What appeared to be happening to it was that it looked like the fast idle cam would never ever come into contact with the adjusting screw. Does someone have pictures of this arrangement - Mostly interested in the relation of the fast idle choke cam and it's screw. The steps for that cam to me appear to be worn - I don't know what good ones are supposed to look like.

The links below are a carb worksheet with an illustration of what I'm trying to figure out...
The 1.094 setting was on the flood side of the equation... I haven't found the 'Happy' setting yet.

http://www.xtuple.org/ppc/carbworksheet.pdf

 

[bubba22349]

Good idea on dropping fuel level to get it to idle better. Is the carb an Auto or Manuel choke? RPM with choke set right is around the 1200 range if it is an Auto Choke the cover needs to be set on the index mark plus 1 or 2 lines lean, so the Fast Idle Cam is set on the step or notch (with a > mark). You also should set your initial advance before you can try to tune the carb correctly. Good luck

 

[1966Mustang]

Thanks for the nod of approval!

This has been the definition of shot-gun troubleshooting. The carb and DUI should have been done when one or the other was working... quite a PITA when you have all these new variables.

It is an auto choke. I'm assuming index mark +2 means +2 in the Lean direction, which would be to the passenger's side right? Index mark is the mark on the cover that stands out (the 'thicker' molded line.)

I've been attempting to set the initial advance (and getting the carb right at the same time...). This is set to 14 degrees on this car. I did set this with the vacuum removed and plugged and the idle set as low as I could get in a moment of carb behavior (800-900 RPM). My thought on setting the initial advance is that it doesn't matter what low RPM you're getting exactly as long as the weights in the dizzy aren't flying out. If the weights aren't flying out, then it should be pretty much a static setting (granted I don't know what RPM the weights on this DUI start to fly out, suppose that might be on the documentation someplace. The weights have a red dot if that means anything). If you could lock the weights in, wouldn't it be a constant? I bet I could tape them closed to find out...

Theoretically - if the dizzy weights aren't moving then wherever that timing mark is - it isn't changing no matter the RPM - in idle, in full throttle, whatever... I didn't do this, but I'm just trying to wrap my head around what the procedures are really trying to tell me the reasons for doing it this way are.

All my other monkeying will be done when this thing is hot and open choke and with a timing light attached to watch the RPM's and the advancing.

Another question - Should it be raining in any fuel at HOT idle? As I'm adjusting my float towards less fuel in the bowl I've noticed that it rain drops in less. This raining at hot is what got me to suspect that I have too much fuel/float level and possibly might have too much jet, which I'm thinking is like a straw - easier to suck up stuff with a big straw than a small one - more vacuum/pressure/area.

Thanks,

Perry

 

[bubba22349]

Your right it's very difficult to get all the settings right at the same time. If you can get the car to idle at 700 RPM in park or neutral (if it's a stick trans) should be close enough to Set the Base timing with the Vacuum line plugged. Don't worry about trying to stop the Distributor weights from moving. It may be better dial back timing to 12 or 10 Degrees BTDC if the Idle won't drop down enough, after you get carb right you can change it back.

Yes you will have fuel raining down the carb with it running both hot or cold this is called atomization because of the Ventura shape inside of the carb it causes a difference in the Speed / Pressure and this then pulls the fuel into the air stream. Getting the correct Air / Fuel Ratio or Mix is the tricky part and the Fuel Level in the Float Bowl is very important to the Idle Circuit of the Carb. A High Fuel Level will make the car run Richer a Low Fuel Level will make it Run Leaner.

 

[Frankenstang]

There's multiple things going on with my car too. Carb was switched from a Holley 1940 back to a 1101. Distributor was changed to a DUI. Engine was rebuilt from the ground up. Different Cam, valves, etc etc.

I'd suggest keeping the moving targets to a minimum. EG set the timing for an initial 10-12* with vac disconnected and leave it be (would not hurt to leave vac advance disabled as you're "re-calibrating" the carb. Set the choke to a straight up index +/- as you like and let it be.

In order to get the jetting and float level set, it will take some trial and error as you are well aware of now, and 'stock' configurations will only be a 'guide' on your modified setup. One note on float level settings though; to make any apples to apples comparison of your float setting to ‘stock’ you want to be sure to measure from the 'stock' measurement locations. IE the "gasket" lip of the fuel bowl lid (on the upper air horn...aka the upper carb body...see first frame of thumbnail diagram below) with the lid inverted. Your diagram (very cool btw) seems to be measuring the float height relative to the main jet stanchion base. This should give lower overall float height readings than if you were measuring from the gasket lip, as the base of the main jet stanchion sits below the gasket lip on the carb lid.

In general, yes you're definitely through the rabbit hole now and a "good tune" on your setup is all 'relative', and not as relatable to stock. As you cam the engine, change compression ratios, and thereby effect VE, you'll have to 'wing' a bit of the tuning...all stuff you seem to allude to or acknowledge in your first post.
But for a baseline/starting point from stock you might go with something like the '66 FSM shows for the C50F-Y 1bbl specs (or another suitable starting point given your carb model):
-That's a 1.2" venturi with a stock 69 jet (67 adjusted leaner for higher altitudes), and a 1.090" float setting...again for 'stock'.
-
With a non-stock cam you're going to have less vacuum directly affecting carb calibration (eg less vacuum can necessitate richer jetting and possibly 'only slightly' higher float settings to maintain proper a/f relationships given your mods/setup). So given your mods the 'stock' numbers become more of a jumping off point than a target as you suggest (ie with particular regards to rpm's for example, as to what provides a ‘good’ idle).

As always more info would be helpful...what engine do you have? what year head, block etc? what cam do you have? what size venturi on that 1bbl? what other mods were done to the engine (head shaved, etc)? All this will be helpful in ‘defining’ the particular tune for your setup…as they say, keep the info coming! Good luck

http://falconfaq.dyndns.org/display1.ph ... age=10-014
PS Fig 14 above has an okay pic of the fast idle screw and cam engagement. The steps and lobes on the fast idle cam are not necessarily ‘crisp’ sharp corners to begin with AFAIK and allow smoother transition to lower idle settings until the engine is warmed up. If you’re not ever engaging the fast idle cam (or for that matter never disengaging) you may want to walk back through your initial bench settings.

 

[1966Mustang]

Ok, so I guess some updating is in order here. I did finally get it running smoothly. The Idle adjustment screw required being screwed out maybe 2.5-3 more past recommended. 69 Jet and set the idle to where it would maintain 700ish RPM in gear. Starts right up, doesn't die at stop lights. Doesn't buck driving down the road. It doesn't smell as bad as it did either.

A little more about the engine block:
C5 block
Cam: 260 comp cams.
Compression is 10.00
DUI at 24 degrees @ 3000 RPM
14 degrees initial advance
44 degrees total
I think i may have to send the DUI out for an adjustment?

I'm not sure what the expectation here should be and I know that everything has to work as a matched system (which I don't have yet...). The engine is much much better than it was before the rebuild, but not so much better that I wouldn't want a V8 shoved in there... (sorry sorry sorry!! Joking! I already had a 66 with a 351W/C6/9" then changed the engine to a 302/C6/9"... long story)

The exhaust is still the stock version single outlet 1.75" traverse design. The exhaust manifold is new, but again - it's the same dimensions as stock.

The head itself is a C5DE. I'm giving the engine builder a call to see if he's got the specs of what was done, as I don't seem to have it in my paperwork from him (I'll post what I can obtain from him). I do not recall what was done on the valve train/head other than all new stuff - Rocker arm shaft, adjustable rockers.

If I really get an itch then I'll jump on the big log or AI head bandwagon, but there is suspension stuff I want to take care of first.

The most important thing is that I'm able to enjoy driving the car and that I have a good bottom end and an engine I don't have to worry about. And I am enjoying it!

So far, what I've got:
65 Coupe
Rebuilt the original 200 block and C5DE Head
Autolite 1101
Stock style exhaust
7.25" rear end
CSRP granada brake/spindle swap
Redrilled rear axle for 5 lug w/drum
New stock style UCA/LCA
Front KYB's
Grab-a-trak 7/8" front swaybar
DUI from AZMike
3 Core radiator
AR TTD's with BFG Radial T/A 225/60R15
7" Hella headlights from reenmachine

What I want to do on some coming lucky weekend - in order to see how these correct some handling issues.
(Maybe) a Monte Carlo Bar Weber style (Does anyone sell one other than the A600W 01 from MU)
Scott Drake Export Brace
Rear sway bar

Then I'll dig in a little more over several weeks.
Shelby Drop
All four Koni Adj Shocks
Roller Spring Perches
Front Coil Springs
Rear Leaf Springs

Then, back to the engine dept... Of course, any and all discussion and comments are greatly appreciated! If anyone is in the Norfolk, VA area and would like to stop by for a beverage and hang in the garage sometime, drop me a PM!

Thanks,

Perry

 

[bubba22349]

Looks like you have some good plans for the handling part Glad there is some good progress did you check your that float was still good when you had it apart? They can get too be heavy, brass ones sometimes crack or have a pin hole and take on fuel. The Nitro type can also absorb fuel. After you run it and shut it off with the air cleaner off do you notice any fuel dripping down? You are right if you can find someone to do a curve on the
Distributor that will also help. You might look into upgrading the exhaust to a 2 to 2 1/4 pipe that should unlock a little more power too. take care

 

[1966Mustang]

Thanks. The brass float is all good - I had replaced it with one from allstate carbs in NY, (which is also where I got a selection of jets from... although i ended up using the original 69 size... anyone need 62,64,66 jets I have 2 of each?). No fuel dripping back when not running.

I agree that uncorking the exhaust will help, but wasn't sure about the recurving dizzy... I'll see if anyone local can do it.

Thanks again,
Perry

 

[bubba22349]

There is also One of the site members "FalconSedanDelivery" that dose distributor curves.

 

[chad]

There is also one of the site members: "FalconSedanDelivery" that does distributor curves.

here's a second to the quality of the work done there
;^ )