Noob Carb questions

[AbnMike]

I've done a lot of reading on these Zenith carbs on my E3. This is my first BMW but I have had to deal with dual carbs on my old Yamaha RD350 (Not the same, I know - carb balancing there involves putting two WD-40 sticks in the throttle bodies and ensuring they move at the same time...)

So I read the thread in the E9 section about the carbmate and balancing.

I'm not sure mine are not balanced but here are a few questions that I have (I also have the two volume Blue service manuals):

1: Idle is at about 1100. Is that acceptable?

2: At 1/4 throttle there is a distinct stumble. When going from a stop past this 1/4 throttle it hesitates, then kicks in.

3: There seems to be a "rumbling" at around 3200 RPM. Maybe a pulsing.

4: I would want to start with a jet cleaning to ensure they're all clear, however it is not clear from the service manual that if I pull the cover to get to the jets that I'd need to replace a gasket. At this point I am not sure I want to do a full in-depth carb rebuild but I would like to clear the jets (or at least check them). Is it possible to do without a gasket set at the ready?

Thanks!

 

[Stevehose]

1100 is a little high, if you have a/c then 1000 is better, if you don't then 900 is the target. Check that your throttle butterflies/screws are not open too much at idle.

That stumble is usually the accelerator pump and associated jet nozzle assuming timing and ignition, possible vacuum leaks sorted.

The pulsing at 3200 rpm, if carb related, could be an out of balance symptom.

Timing and dwell set per spec?

 

[AbnMike]

1100 is a little high, if you have a/c then 1000 is better, if you don't then 900 is the target. Check that your throttle butterflies/screws are not open too much at idle.

That stumble is usually the accelerator pump and associated jet nozzle assuming timing and ignition, possible vacuum leaks sorted.

The pulsing at 3200 rpm, if carb related, could be an out of balance symptom.

Timing and dwell set per spec?

I need to check the timing. It's been updated to an electronic ignition so no worries on the dwell. I know I have an old timing light I used on a small block chevy, I'll throw it on there and see what the result is.

I think that the throttle butterflies are open a bit too much, but that's just memory as I recall looking at it.