I have this lousy gasoline in here My Mercury has original carburetor. Its getting Lean spot when you just start to press accelerator. I clean to whole thing. Adjust float level bit higher, on hi end of factory tolerance. Would it help to enlarge Idle pickup tubes little bit, or is there other ways to Make this work?
Make sure measurement of fuel height in the bowl is correct. Float height is only the means to get close. Adjust float up or down as required to achieve correct fuel height. Let the engine idle for a few minutes with car on level ground. Shut the engine off, remove the air horn, and measure the fuel height. Not the float height, the fuel height, this is a common misconception. Make sure ignition timing is correct, as there is very little air movement through the venturi at idle, or just off idle, where most driving is done around town. This affects the engine manifold vacuum. A stock engine should have a high, steady vacuum. Also the 2100 series has the overtravel lever - with four (4) possible adjustment holes to choose from. The uppermost slot is for temperatures below 40° F., the second from the top is for temperatures between 40° F. and 90° F., the size of the carburetor accelerator "pump shot" is reduced in warmer weather. The "idle mixture" screws should be leaned out as far as possible consistent with a smooth idle. Most people have them set way too rich. A "lean bog" is sometimes difficult to distinguish between a "rich stumble", and the spark plugs will soon start to load up and foul. Though they are "idle mixture" screws their are in circuit till about 35 miles per hour. Make sure the power valve (economizer) is the correct value for your local altitude and specific engine vacuum, and that it is not leaking. The gasoline will soon degrade rubber compounds.
I did measure Fuel level.i dont have 63 shop manual, so i use closest i have, 1960 Ford car shop manual.and i choose closest engine, 352 2v. I do have adjust ignition timing.i have sun distributor bench and i have verified that distributor is working as it should Be. I dont think its Power valve or main jet issue. Lean condition comes when you cruise about 1-5 mph and feathering gas pedal.also i can open butterflies when it idles on park and can hear/ feel when its getting Lean and then gets stoich when main circuit comes on. Hope you understand.
I.was.trying to Post a short video, but its keep telling that file is too big. Anyway, when it idles on park/ stationary an you start to open butterflies, there comes spot where motor allmost dies, it goes so lean.open flaps bit More or less and everythings is fine.
OK, sounds good. There aren't very many adjustments to be made on the 2100, but, every single one is important. If you dig around the internet, should find a few Autolite 2100 manuals in .PDF, these are great, be sure to study these, and general carburetor theory. One thing that can cause trouble with the 2100, if it has seen long use, the throttle shaft rod will cause excessive wear clearance "slop" in the air horn body introducing an air leak. It is also common for the carburetor flange surfaces to become warped, due to overtightening.
But it does sound like a power valve issue that is not opening at the right time. The kit power valve is just a standard. You may have to go either side of the one in the carb to stop is from hesitating
Thank you for advices. I do have Rochester, holley and Carter manuals and i have studied and understand theory of how carburetor should Works. I do admit, i have leaks in exhaust system, and on My experience, it do affects as leaning Fuel curve. I did check trotthle shaft wear, and there is no noticeable wobble. I do notice The booster assembly looks little warped and i gently bend it Back to level and put new gaskets on there, nyt that dont change nothing. I have good Idle, adjusted it bit on The rich side. Good stady main circuit/ cruise condition and good strong Power circuit. All i have trouble is this transition circuit/ low speed cruising.
Well, there is press In brass Jets on booster assembly, that measure Idle/ transition circuit Fuel/Air emulsion. I did dril those bit larger.they where about 1,2 millimeter, and i dril them 1,5 mm. Now The Lean spot is allmost gone.i better Make some drive test to Make sure, i go to right way. I can allways solder them shut and dril again on smaller hole.
I have the same problem pontmerc ! Very curious if drilling out that brass jet in the booster cured your problem ? Can you explain more where it is located ? I have a fat idle, very lean «barely off the throttle» and trying to find out how i can make the transition cirquit a little richer.
Does the accelerator pump have a good steady stream of fuel when you open the throttle? If not look to a faulty pump cavity check valve.
If this is only when you are tipping the throttle in slowly, (not flooring it) look at the main circuit. Specifically when the throttle blades are opening and you are transitioning from idle circuit to main circuit. 2100/2150 are not "fussy" like a Holley.
When you adjust idle the idea is to get it to idle with the least amount of throttle opening. Ajust the mixture screws to get the highest idle speed. Then adjust the speed screw to get the rpm where you want it and repeat until you get it to idle with the least amount of throttle opening. It should not be idleing on the transition slots. Some times on a modified engine it may require a small hole drilled in the throttle plates engines with low vacuum.
Before you start on a lot of messing with the carburetor, replace this piece: It's called an accelerator pump diaphragm. Search for "accelerator pump diaphragm Ford 2100". Note there are a few different styles, even for the 2100. This diaphragm becomes less flexible over time so does not squirt a sufficient amount of fuel when the throttle is opened. It should cost about $10, of course shipping to Finland may be more.
Pontmerc, Did this problem just show up one day or did you buy the car or carburetor with this problem? If you can gently pull out the tubes from the booster, maybe you can use a piece of glass and sandpaper to lightly sand the booster assembly flat.
Problem was there when i first got it running condition.i did drill those transition orifices bigger and flat spot disappeared. Since then, i sold car and next owner dont complaint how it function. I do recommend first check accelerator pump and spark quality before Make any drilling.
The Jalopy Journal
