Autolite 2100 "lean condition"?

Hi all,
I posted recently about my late model large log head having had its carb bolt pattern changed by a previous owner... I was able to resolve that and mount the Vintage Inlines Autolite/Holley 2v Adapter. Cool. I also purchased an Autolite 2100 1.02 (245 CFM) from Rockauto as the Carb.

Now, when I was researching which carb to use, I was considering a 2100 0.98 (190 CFM) from a 1962 Fairlane because it was closest to the original Autolite 1100. After reading about CFM and calculating a conservative value, I came to believe the Inline 200 is capable of around 250 CFM (maybe this is my mistake?)

Anyways- back to now, I have everything bolted up and the car fires up and idles smooth, drives nice cruising, but has a wicked stumble and some tailpipe backfiring just off idle. Everyone is telling me that means it's lean, so I've adjusted the accelerator pump to what I believe is it's max shot, but I can't change this off-idle "lean condition".

Photo of the pump setting:


Other details about the car:
-DUI Distributor and wires, new plugs. Pushing ~30 (or 32) degrees advance.
-New fuel pump/filters/hoses.
-Vacuum idle is 20, if I really juice the throttle is behaves nicely, doesn't appear to have any vacuum leaks.

What's the base timing? You might want to check the timing chain gears for excessive slop too. Good luck

Hi, you will get the most accelerator pump squirt if you put the rod on the diaphragm lever to the outer position. But I don't think that would help. Your problem could be when the pump squirt starts, and not the maximum amount of fuel.
The correct setup will have the accelerator pump linkage completely relaxed, and begin to squirt fuel as soon as you give it gas.
It is easy to see the pump squirt with the air cleaner removed and the engine off.
Good luck

bubba22349":19f2zk7s said:

What's the base timing? You might want to check the timing chain gears for excessive slop too. Good luck

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I'd have to check. Given what you know from my post, what would you aim to set it at?

It actually ran pretty OK before with the Autolite 1100- dare I say I went this route for "looks" and to hopefully improve some of the 1100's weak spots.

Initial Timing is 2 degrees BTDC

When I look down the carb bore and push the throttle with the engine off I see shots of gas immediately. With the engine running, they appear weaker/shorter.

Hi, these engines like more initial timing. Try 10 or 12*. As long as you don't get any pinging when you accelerate. Do you have the vacuum advance plugged into ported or full manifold vacuum? Ford used ported vacuum from the factory. Good luck

Bumped the initial timing up to 12 degrees. No help.

Good on the 12 degrees base timing! Well at only 2 degrees base timing with the Autolite 1100 you giving away a lot. Have you checked the wet fuel level in your new carb yet? How much fuel pressure do you have at the carb? Also these HEI distrbitors are notorious for having the wrong timing curve.

bubba22349":2aif16ma said:

Good on the 12 degrees base timing! Well at only 2 degrees base timing with the Autolite 1100 you giving away a lot. Have you checked the wet fuel level in your new carb yet? How much fuel pressure do you have at the carb? Also these HEI distrbitors are notorious for having the wrong timing curve.

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Good point, the fuel pressure could be low. When you say "check the wet fuel level" do you mean the level in the float bowl?

Yes with an Autolite or Motorcraft carb you can take the carb top off to check this with the carb still bolted to the engine.

bubba22349":76ecyjz2 said:

Yes with an Autolite or Motorcraft carb you can take the carb top off to check this with the carb still bolted to the engine.

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Ive adjusted a dry float, what am I looking for with a "wet level". I pulled the top of the carb, it looks normal(?), the bowl is full and the float needle doesn't appear to have any more downward play.

Measure the fuel level down from the parting line of the carb bowl. This should eithe be 13/16 or 7/8 within + or - 1/32 of an inch depending on its orginal use try the lowest setting first. While the top is off also make sure the float can move without sticking on the Red accelerator Diafram sticking into the fuel bowl sometime people will forget to clip this off off during a rebuild or not cut them off enough so the float can move easily, should be about 1/8 inch past the little nob coming through the hole. Edited

bubba22349":q7kc1j29 said:

Measure the fuel level down from the parting line of the carb bowl.

Click to expand...

Thanks Bubba. I'll have to check tomorrow, Ive run out of time today. If I may, where is this going? Whats on your mind?

Yes ok the wet fuel level is always the most accurate way to measure the float level setting. Also Recheck my upper post I edited it with some additional info. After you have checked this and fuel pump pressure at carb inlet you can rule out that it's caused by a carb issue and at that point you will need to focus on ignition causes. Best of luck

You need to check the A/F ratio with a wideband tester. That way you can see what your cruising ratio is & when accelerating. Then check ratio at WOT.
Otherwise you are just guessing.

bubba22349":3j2lqast said:

Yes ok the wet fuel level is always the most accurate way to measure the float level setting. Also Recheck my upper post I edited it with some additional info. After you have checked this and fuel pump pressure at carb inlet you can rule out that it's caused by a carb issue and at that point you will need to focus on ignition causes. Best of luck

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Ok, I'll try this tomorrow.

Another question: Re-reading the "handbook" they call out the 1.08 2100 as the "best choice mostly stock 200" - At 287 CFM, I assumed that world be too much carb and that the 0.98 and it's 190 CFM would be more appropriate for a stock 200.

Thoughts?

The 0.98 Autolite is small for a stock 200 even the orginal stock 1V carb was also quite small. Remember that these engines were orginally designed and built for economy rather than performance.

With a mickey mouse rebuild carb. you have no idea what was done during the rebuild.
Make sure you are using spiral wound spark wires.
Gap your spark plugs to .045"- .048".

bubba22349":e1206b1g said:

Measure the fuel level down from the parting line of the carb bowl. This should eithe be 13/16 or 7/8 within + or - 1/32 of an inch depending on its orginal use try the lowest setting first. While the top is off also make sure the float can move without sticking on the Red accelerator Diafram sticking into the fuel bowl sometime people will forget to clip this off off during a rebuild or not cut them off enough so the float can move easily, should be about 1/8 inch past the little nob coming through the hole. Edited

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Bubba, another question for you.

Im running the stock Mechanical Fuel Pump, which is rated at "6 PSI System Pressure" and "30 GPH". I'm waiting on a Fuel Pressure Guage to confirm my actually system pressure, but it was running fine with the Autolite 1100.

Is there any reason this pump would be causing issues for the 2100? When I look at pumps from those 2v engine configurations they list "5.5 Max Pressure" and "40 GPH".

spacecadet":20o1jyg2 said:

Hi all,
I posted recently about my late model large log head having.....
Photo of the pump setting.

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Just from the pic (& it bearly shows this aspect) I'm wondering if ur throttle cabe binds @ the VC?
Have the throttle blipped frm inside the cab w/hood open. C if it comes dwn onto VC during that process?
Nah...just an illusion?