BUDA engine, Michigan Motor Car, Stromberg B No. 4 Carb

Searching the net I see that Mark-IA has a 1912 Michigan automobile with a Buda engine & Stromberg B No. 4 carb. (posted here on Feb.19, 2018) I'd like to speak / correspond with Mark-IA about both his and my 1912 Michigan. Mine is in process of getting restored. It's been in my wife's family since new. We got the motor going TODAY- Aug. 1, 2018, but it wants to race and will not idle down. I suspect timing & carb issues. Any help from forum members is appreciated. You can see my efforts at: www.michiganmotorcar.com

Buda engines were used in a whole list of early fleet cars and trucks. Some tractors as well. They are very robust motors for automobiles. Thanks for your assistance. I hope to hear from Mark-IA -- thanks, Craig Correll in Carlsbad CA.

Anybody know Mark-IA? I'd sure like to talk with him. Thanks

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I am not a Buda engine specialist, nor am I an expert on the Stromberg B 4 carb.

Here is a link to an online reference for a B 3 carb. I hope they are similar enough that this can get you started.

http://forums.aaca.org/topic/255886-stromberg-b-3-carb-info-needed/

Now, as far as race condition, the engine speed will always, always, always be determined by the volume of air, and fuel being introduced. I'm sure you know this. Look for areas where air may be getting in that is not part of the metered means through the venturi of the carb. #1. Throttle shaft loose in the bore. It is always downstream from the venturi, and causes many vacuum leaks, which are compensated for by making the fuel mixture richer. #2. Intake manifold flange, and gaskets. I'm sure you are using new gaskets, but make sure the flanges are clean and flat. A warped flange will let in a lot of air. #3 Cracked intake manifold. Hard to see, not common but possible.

Read all your plugs. If they look light brown, then the mixture is close, but you are compensating with added fuel for a vacuum leak. ALL the air for the engine must come through the venturi. It is the only way to properly meter the mixture. I would get it started again, then back off the low RPM and the main fuel jets (A and B nuts in the diagram) so that the engine is running as lean as possible. Then, once it is running very lean, use a can or carb cleaner spray on the various parts of the carb and intake to identify vacuum leaks. When you spray on a leak, the rpm will go up quickly as added fuel reaches the engine.

There is also something called a "Gunson ColorTune" that can be very helpful in old engines for setting the right mixture. Can be bought on Amazon or Ebay. Gives a very clear visual indication of correct mixture settings. I use it on old Ferraris to tune each of 12 carb bores, for each cylinder. (and I charge a lot of money too!). Lucky, you have only one carb to adjust.

Thanks Doc!
The interesting part of these early Stromberg carbs is that they are so doggone basic. There is one jet up thru the center of the carb and the air/fuel mix is regulated by opening and closing the "auxiliary air valve". It is essentially a way to introduce MORE AIR at the right time. There is no way to regulate the amount of fuel delivered. That is simply a function of the volume of air going thru the venturi / amount of vacuum pulled. Your suggestions - links were helpful and I'll keep trying to get this thing to idle down. Thanks again.

(quoted from post at 16:27:41 08/06/18) Thanks Doc!
The interesting part of these early Stromberg carbs is that they are so doggone basic. There is one jet up thru the center of the carb and the air/fuel mix is regulated by opening and closing the "auxiliary air valve". It is essentially a way to introduce MORE AIR at the right time. There is no way to regulate the amount of fuel delivered. That is simply a function of the volume of air going thru the venturi / amount of vacuum pulled. Your suggestions - links were helpful and I'll keep trying to get this thing to idle down. Thanks again.

Click to expand...

That's interesting. Rather than a throttle set screw, they would use an aux air bypass. This is common on new FI setups where the valve is a solenoid run by the fuel inj controller. The bypass should be tested as fully closed. I can now see how the casting has the bypass around the throttle plate. Air must be getting through there and feeding the engine.

I would still suggest doing the vac leak tests, but also figure out how to close that bypass valve.

According to that link, it says there are two adjustments for fuel mixture. There must be fuel mixture adjustments. One for the idle circuit, and one for the main circuit. The link discusses how to adjust them.

Here is an exploded view of my Stromberg B No. 4 carburetor. Other than being BIG there isn't much to it.

Here it is re-assembled. I think I know that the trick is getting the low speed control dialed in. When I do, it should - should- idle down. I'm keeping my fingers crossed until then.