2800CS low RPM sputter

[M.Burroughs]

Hey guys,

I'll preface by saying I'm a youngster with little knowledge of carburetors. I come from the land of E28s and fuel injected M30s so I'm a bit stumped on where to start as far as resolving an issue that has come up.

I took the E9 from Newport to LA and back yesterday. The car handled the trip perfectly and had no issues. Pulling in to the parking lot back in Newport, the car kind of sputtered at low RPM. I figured maybe it was just the heat and parked it and came back today.

I just took the car around the block, and its got a low RPM hesitation/stutter, up until about 1500RPM. Above that it seems to drive pretty normally. No issues. It idles fine for the most part as well.

The issue is odd because I drive the car every day and have never had an issue, including much longer drives (I drove her 21 hours straight up the east coast last year.)

I figured I'd ask for some help in diagnosing the issue. I'll report back later today with a video/sound clip of the issue for more help.

 

[sreams]

Does you car have the origial carbs? Or does it have webers?

-Scott

 

[M.Burroughs]

It has two downdraft carbs. I am not sure if they are original or not.

 

[HB Chris]

Mine started running rough but seemed smoother above 3000 RPM. Thought it was the carbs. Turns out it was the points which were pitted and had closed up. The Pertronix solved that issue.

 

[61porsche]

M

your early photos show two large chrome air cleaners rather than the one piece air cleaner for the zenith carbs. My guess is that you have webers.

As Chris says, it's more likely ignition. So check the points condition ( no blue, pitting, burning, etc. regap, set the dwell, and retime. Before touching the carbs.

90% of all carb problems are usually ignition related. The other 10% is usually just one carb so finding out which one is important.

Take off the air cleaners, peer at them to see if there is any obvious flaw such as "dripping fuel" at idle. If so, one of the carbs floats aren't sealing properly by dirt or wear and causing the stumble by an abnormal high level of fuel.


There's more , but check those first. Hold on to your screwdriver, it's not needed yet.

 

[dj_efk]

Hi Mike, firstly can I start by congratulating you on your stance skills -I'm on Retro Rides and I think you know there's a strong fan base on there.

http://retrorides.proboards.com/index.cgi?board=general&action=display&thread=108423&page=1


My strong opinion is that you want to upgrade to electronic ignition to banish ignition woes and to give you better starting / throttle response and smoothness.