Distributor /Carb /Timing ?

alotawatts · Post by **alotawatts** » Mon Mar 02, 2009 8:12 pm

I'm posting this because I'm curious. He's a local club member. Car is a 70 2800CS Shark I think - Ideas ?

On my 'new' coupe - There seems to be a question regarding the ignition distributor... There is a pronounced hesitation just off idle that causes some drivability problems (and just makes it plain hard to drive smooth regardless).

The car has the stock 2.8L M30 engine with the original Bosch distributor.
The car has only 100k on the clock but 39 years is 39 years....

New distributors are available (for a price of course - if you know what dusty shelf they are on) - but knowing I have issues with my unit in the first place would be good to know about if that is even an issue (bad dist or need to rework or...???)

Mike W. · Post by **Mike W.** » Wed Mar 04, 2009 9:35 pm

It's the carbs, not the distributor or timing. Having put over 100K on Bavs, I got to know them well. I found I could either eliminate the flat spot but very shortly end up with a very iffy idle, or have a decent idle and a flat spot. Later carbs may (or may not) be better, but I had a pair of 69 and 71 carbs and they were just terrible for drivability. Not bad on either economy or power, but horrible drivability. I eventually put L-jet off a 530i on it and what a difference. It was just 100% a better car, parking lots were no longer hit or miss with your foot ready at any time to stab the clutch, cold starts were no longer a problem, just a much better car. I did however lose some low end power and a MPG or two. But a small price to pay.

Back on the distributor, it works best with both the advance and retard sides hooked up, I forget the vacuum routing now, it seems like it was odd, but it was better with both working.

alotawatts · Post by **alotawatts** » Wed Mar 04, 2009 11:42 pm

Thanks Mike !

lip277 · Post by **lip277** » Thu Mar 05, 2009 10:29 am

Hi-
I was the one that asked the original question on the local Seattle CCA BBS.

The PO of my car had the carbs gone through by an experienced and local (to him - Portland, OR) mechanic some time ago.

They (the Zenith's) were reinstalled and have run fine in all other respects since then. There has not been a whole lot of formal diagnosis of anything since then to address this isuse. I only bought the car last October and have put more miles on it since then (even living in Seattle) than the PO did in probably three years...

The perplexing thing to me is that just about no matter how slowly I push the throttle, the hesitation is there... I would expect if it was the carbs - the hesitation would not be that way...
But this is my first car with Zenith's.

My 2002 had the OE Solex then Weber 32/36 and now 38/38 so that is a different animal. My Mustang... hehe... no comment.....

In talking with the PO and a couple of other folks here (including a mechanic friend who has TONS of expererience on MBZ's with these carbs as well) - They seem to focus on the distributor... So... That is where I am coming from.

It starts up just fine...
The only other 'issue' I am having is the car does not always want to idle at the lower engine speed once it comes off choke. When that happens, I can blip the throttle usually to get it down from ~1400 to ~800 RPM. Might be the linkage hanging up or something simple.

Again -
I'm just getting into this car and have only had time to perform my 'starting' maintenance on it... Oil change, plugs, cap/rotor (has Pertronix already), adj valves and the like.

VERY nice car to drive even with these two small issues as I note above.

Just wanted to introduce myself here and round out the story...
Even though it's not an E12, I'll be around.

Thanks - - -