Member
On my 79 320i converted to a weber 3236 I have a slight bog that for the life of me i cant find. It only happens at about 2500-3200 rpm and only while driving. Also its way more noticeable when the car is cold. The carb i got rebuilt about 3 months ago, pertronix ignition swap, new coil, new spark plug cables and plugs, dist cap, rotor, new fuel pump and filters (pre pump and glass filter before carb, Air filter all about 3 months ago. My fuel pressure gauge marks 3 psi. The timing was also double checked by my mechanic since i dont have a timing light handy. My glass fuel filter doesnt have any varnish or debris. About a month ago i had to take it to my carb guy to readjust the float because on stop signs it would want to die on me. My vacuum gauge shows 19 inches with the needle a little bouncy about 1/2 inch on the gauge.
I am really lost because everything is checking out ok. I hear my clutch bearing noisy when I am at a stop sign but i dont think the issue is drive line related.
Also ran it with advance disconnected and giving the carb a little more fuel and same thing. Ive noticed its while lightly accelerating from about 2k-3k, if I hit the gas hard like if im getting on the freeway it wont bog at all.
Last edited by e21Luis; 01-21-2018 at 07:13 PM.
Member
Might be carburetor related, and might be this thing -
Accelerator Pump Diaphragm Assembly, Weber 32/36 DGV
If your car bogs down exiting corners, your accelerator pump may not be pumping! When the throttle is opened all the way from idle, the accelerator pump should deliver a shot of fuel directly into the carburetor throat. If this shot is not visible (with the engine off), the diaphragm may have gotten stiff with age. A torn diaphragm will allow fuel to leak out of the carburetor. (Race gas may leave a tell-tale purple stain on the outside of the carb body.)
This diaphragm fits the Weber 32/36 DGV (including 5A), DGAV, and DGEV progressive carburetors as well as the DGAS/DGES synchronous carburetors.
Does not fit DFV / DFAV / DFEV series.
http://www.pegasusautoracing.com/pro...asp?RecId=4133
Member
The bouncy vac gauge could easily mean the engine needs a valve adjustment. Valves tend to tighten on the M10, especially on high mileage heads.Originally Posted by e21Luis
When the carb was 'rebuilt' - were all the passages checked for flow before assembly? An old trick is to blow smoke from a cigar into the vent(s)/passages and watch for good smoke flow out the smaller fuel/air ports.
Sometimes the small fuel ports in the venturi, next to the throttle plate will get overlooked, most if not all carbs have these ports in the same area. In this picture you can see four small fuel ports above the fuel mix screw, three of these ports act as the 'low speed fuel circuit'. If any of these ports get clogged/dirty - low speed 'stumbling/hesitation will usually occur. Sometimes just spray-can-carb-cleaner will help, but not always if they are clogged. I've used a strand of copper wire to unplug these ports, don't use force or break the wire strand in there...
I don't know what kind of carb this is, just showing the ports I described.
click to enlarge
carb-IdleCircuit.jpg
Last edited by epmedia; 01-21-2018 at 09:59 PM.
Tbd
Member
Well now that i checked the carb to see how my secondary was opening Im only seeing the primary injecting fuel. Ive tried moving the linkage a couple times and the secondary venturi dry. Could this be due to a failing accelerator pump?
Member
IF the carburetor was "rebuilt" without installing a new accelerator pump diaphragm that was a mistake. But there could be other problems as well like blocked passages as mentioned above. Sounds like you are narrowing your problem down.
Member
Does that carb even have a second accelerator pump? If not, I would not expect any fuel to squirt in the secondary.
E21 Addict
The 32/36 only has one accelerator pump, and it's in the primary. If your jets are not properly sized, you will bog down regardless of your pump squirting fuel, because honestly they really don't pump very much... I had a similar problem a while ago, turned out to be vacuum leaks.
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