I've rebuilt the webers on the bavaria and have them synchronized well enough to move the car about. The webers dont have a ported vacuum access on the carb body and neither do the manifolds. the rear manifold does have one ported vacuum access but front manifold has only the port for the brake booster hose. Does anyone have any information on synchronizing the weber 32 36 carbs and where to access ported vacuum for use with a synchronizaion tool whether its a tool such as the carbmate or a simple vacuum gage. Any information on how to synchronize appreciated
32 36 carb sychronization
- Thread starter bavagain
- Start date
The brake booster port and other manifold provides “manifold” vacuum not “ported” vacuum, meaning the signal is highest at idle with butterflies closed. This is what you want for synchronizing using a vacuum gauge like a Carbmate. Ported vacuum is zero at idle and increases when the butterflies open until it then drops off. Once the throttles open to a certain point, ported and manifold vacuum are equal. I’ve never seen a 32/36 without both ported (above the throttle plate) and manifold (below the throttle plate) take-offs. Some pics would be helpful because these need to be capped if not used for vacuum advance. The best way to synch these is with a Synchronmeter and matching dgav adapter as John mentioned.
Synchronization of 32/36’s on the M30 should be a very straightforward operation that you do not need vacuum ports to accomplish. Even a length of fuel hose used as a stethoscope down the primary choke to audibly hear and balance the air volume will suffice.
This all assumes a healthy engine, correct timing/dwell, healthy ignition components, Webers are correct assembled/functional, and jetted for your M30:
Remove the throttle linkage input from the body (ie to gas pedal) and likewise separate the carburetors from each other (ie disconnect ball link arm), use the idle speed (throttle opening) adjustment screw to close both primary throttle plates, wind them open equal amounts (maybe 1 turn?) from the point at which they act upon the linkage—be fastidious, you can even use a feeler gauge. Set your idle mixture screws evenly, whatever is recommended (1.5-2 turns out from closed?), start the engine. With as low as possible idle rpm, set idle mixture (highest rpm via mixture), once highest idle is achieved via mixture alone, set idle speed to correct rpm via equal adjustments of both carbs. To synchronize, listen to the air volume with engine running via a length of hose in your ear—stick it down the primary throat while running, hear the “hiss”, adjust so that both are the same dB level correct idle rpm. Reconnect the two carburetors such that the linkage does not influence either throttle plate, use the factory thumb wheel if still present. Reconnect the linkage from the chassis/gas pedal. All done.
Whole operation should take not more than a few minutes once up to temp.
This all assumes a healthy engine, correct timing/dwell, healthy ignition components, Webers are correct assembled/functional, and jetted for your M30:
Remove the throttle linkage input from the body (ie to gas pedal) and likewise separate the carburetors from each other (ie disconnect ball link arm), use the idle speed (throttle opening) adjustment screw to close both primary throttle plates, wind them open equal amounts (maybe 1 turn?) from the point at which they act upon the linkage—be fastidious, you can even use a feeler gauge. Set your idle mixture screws evenly, whatever is recommended (1.5-2 turns out from closed?), start the engine. With as low as possible idle rpm, set idle mixture (highest rpm via mixture), once highest idle is achieved via mixture alone, set idle speed to correct rpm via equal adjustments of both carbs. To synchronize, listen to the air volume with engine running via a length of hose in your ear—stick it down the primary throat while running, hear the “hiss”, adjust so that both are the same dB level correct idle rpm. Reconnect the two carburetors such that the linkage does not influence either throttle plate, use the factory thumb wheel if still present. Reconnect the linkage from the chassis/gas pedal. All done.
Whole operation should take not more than a few minutes once up to temp.
Excellent info here. I will add I found a mixture screw on my front 32/36 was gummed up and I could never get the carbs right. Took a few flesh burning moments reaching in and around the hot manifold and coolant hoses, to realize one screw just was not responding. Removed carb, cleaned and chased that thread of the mixture screw opening. and tuning was easy and accurate after that. Good luck
That's the best most straightforward description of how to tune these carbs i've read recently. I've been so busy lately I havnt had time to fine tune the carbs but i will certainly use the tube method as my first try at it. I will use the carbmate to verify because that's just in my dna but i suspect there will be no appreciable difference between the tube method and the carbmate.