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1969 BMW 2002 Manual Choke Help

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I have a 1969 2002 with a manual choke. We found it in a barn in Everett WA and it has been siting there for fifteen years. We rebuilt the subframes, brakes, replaced all the bushings and now are working on getting it tuned. It has the single barrel Solex carb (36 I think?). I have new gas, filters, plugs are new and gapped to spec, timing is on the mark, but it runs rough. I set the idle about 800, changed out the brake vacume booster hose and verified the other vacume lines are tight. I work on marine diesels and have never worked with a manual choke before; could you tell me when the choke is pushed all the way in or out, the butterfly should be fully closed or all the way open--is that right? Any other items I should do to the carb/fuel system to get a clean idle? Thank you for your help.

Richard

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when you pull the choke knob out on the dash the choke should be closed, as it decreases the airflow and thus richens the mixture. you might want to remove the carb and check for looseness of the throttle butterfly as the throttle shaft can wear the bore of the carb body and leak air into the system and that will affect your idle.

those are good, underappreciated carburetors in my opinion. very torquey on a stock engine. i like them. great for in town driving.

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pushed in...all the way open. Clean idle jet for smooth idle

I second this...on occasion my 1600 pukes out, and I pop the idle jet out and clean it with solvent and it fixes it everytime.

Don't give up!

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Having owned a few 2002's and a 1969 4 door 2000 with the single barrel Solex, periodic cleaning of the idle jet as Jerry and eastsidebimmer mentioned is key but I'd go an extra step since the car was basically sitting for 15 years, a general good cleaning or even a minor rebuild might be a good idea or at least if cleaning of the idle jet really smooths it out, have a rebuild kit on hand, this way you'll have a spare accelerator pump diaphragm among the rebuild kit; most 2002 parts suppliers still carry the 1 barrel solex rebuild kit. I bought one from Carl Nelson at La Jolla Independent a few years ago.

Tim

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As others mentioned, idle jet should be cleaned as the oriphice will clog with minor debris in fuel. All fuel filters snd fuel pump should be thoroughly checked because when they deteriorate all the debris ends up in the carb. These carbs are very sensitive to debris / dirt. After running low on fuel or working on the carb, these idle jets will often clog. The car becomes just about undriveable. The Fuel / Air mixture needle should be turned / calibrated to the right position. As the engine warms up, this needle mixture set screw should be reset as the correct setting can only be determined at normal operating temperature. Before this needle is set, you should remove it and inspect the seat in the throttle body where it sits. When you look into the seat, it should be smooth. The needle must never be turned in so it touches or damages the seat. That is why a spring is provided behind the needle. The carb should be thoroughly examined. If the plunger / piston in the lid of the carb has punctured through the lid, the carb can not be set. These carbs are simple to set. They are just about set and forget, although maintenance is required from time to time. Refer to a manual which covers these carbs. All 02 manuals ususally have an exploded view of this carb and explain the setting / tunning procedures.

Your ignition timing must be checked and set correctly (Points / Dwell & Distributor). If it is off, you'll never get a good idle. I always set my using the static method, and it works like a chram. This method is explained in the manuals. You don't need a timing light.

Slavs

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Guest Anonymous

Vacum leaks, check carb shaft as mentioned before, then carb mount to manifold, then intake to head, I start by plugging all vacum ports then connecting to see if component has issues, Carb spray is my poison of choice but have heard soapy water will work also, I kinda like the smell of burning fumes first thing in the morn. Also check your valve adjustment, too tight and it will rumble like a bad gut.

Dave Miller

DBMW2002

a few o2s and 3s

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that came equipped from the factory with trash in the idle circuit--folks who recommended cleaning the idle jet are spot on...it took me almost a year of periodic cleaning to finally get all the factory spec trash out of my fuel system...

One more thing to check--the vacuum advance diaphragm on the dizzy. The engine will run very well with the vacuum advance not functioning, but won't idle worth a damn...disconnect the hose at the carb end and suck on it--you should feel resistance, and if you pull the dizzy cap off, you'll see the point plate move slightly. If it doesn't or you feel no resistance, your vacuum advance is shot and is causing a vacuum leak, thus upsetting the idle. Also check for other vacuum leaks with the appropriate tools--a spray can of carb cleaner or an unlit propane torch. With the engine running, the idle will increase when either are brought near a vacuum leak.

BTW, if your '69 has a VIN lower than 1665200, it has some early parts in the clutch, clutch pedal assembly and elsewhere that are different from the later cars...and even more unique stuff if the VIN is below 1664761...

cheers

mike

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Thanks Mike, that's exactly the problem, the PO put a rubber tube with an unsealed screw in the end on the bottom of the carb and was sucking air. Fixed it and it roared to life, but now the fuel filter is clogged with rust particles. I'll have to find a place in the Seattle area that refinishes gas tanks. Appreciate the help.

Richard

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Chamonix72 should swing in here and mention where he had his tank redone. They did a beautiful job!

Also if you end up needing another carb, I think I have 2 of em... Yours free.

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