Zeniths revisited

[Mark V]

I've started to look at the zeniths again. I have all the adjusting and setting info etc. but after reviewing everything I have here, I'm puzzled by one condition my car exhibits.

When I hit and realease the throttle, the idle doesn't come right back down. It decays most of the way down taking about 3-5 seconds, then the idle decays more slowly about 10 seconds back down to low idle. That is if the engine is very well warmed up, if not, (like less than 1/2 hour of running) the decay travels right past the low idle to stall.

Now the dashpot is there to keep the engine from stalling when the butterflys slam shut, but mine doesn't work so thats not it.

I've never had the kind of throttle response there you hit the throttle up and it comes right back down smoothly and to a firm low idle. How do I get that?...on this car.

Mark
'69 230/8

[Mark V]

I've learned a few things today.

The first is its best to check the accelerator pump stream with the engine off. Duh. Kids love the eyebrows though!

Second thing I learned was: If you know a vaccuum diaphram is not working, fix it or plug the line going to it cause its a leak. I didn't say any of these would be terribly insightful.

Third thing was: Good tools, especially diagnostic ones make a huge difference. I bought a digital dwell/tach/auto multimeter today and its awsome. I tossed the cheap needle gauge one I had though I may mount it on a plaque to serve as a reminder.

The Fourth: Its possible to figure these blasted things out using good advise, patience and persistance. Its now running much better, smoother, way more stable and it doesn't miss much.

The one thing I didn't figure out was what Arthur and Mike were talking about a few weeks back. The whole timing at 3500 and the retard setting at idle. I have the idle set about 30 degrees ATDC at 3500 rpm. At idle it I have 10 BTDC with and without the vacuum hose connected so I'm guessing it isn't working. I can disconnect as Arthur suggested (I have the 2.3l 6 cyl and a manual trans) but does that mean I have to re-time at idle to get 2 BTDC and let the timing at 3500 fall where it will? Higher idle speed makes sense as at 750-800 rpm I find I come dangerously close to stalling when I leave stop signs.

Are these diaphrams available still?
I'll play more tomorrow, mainly setting up the choke, I may pick up a vacuum pump to check the retard linkage properly. I've been up since 4 now, I have to stop or I'll probably take off my fingers.

TIA.
Mark

[gmask]

Third thing was: Good tools, especially diagnostic ones make a huge difference. I bought a digital dwell/tach/auto multimeter today and its awsome.

Who makes this meter and what did it cost? I've been shopping around...I'm also looking for a compression gauge.

[ctaylor738]

I was able to get a diaphragm for my 73 280 distributor from Mercedes. They had to order it, though and it took about a week.

[Mark V]

gmask,
The one I bought is an Equus 4340, Not a top brand but it seems to work well, I expect you could find it at a parts store near you.

Thanks Chuck I guess thats where I'll have to go if I need it.