Being off by 2 hundreths of a mm is not a bad thing.

That big screw is indeed what you're looking for. If the mechanics that have checked out the car in the past and failed feel guilty, ask one of them to check the CO setting once you adjust the idle. You may need to adjust BOTH the screw and the little knob on the brain box. But touching that knob w/o also sniffing the tail pipe is useless, since you have absolutely no way to measure the effect.

Also, should you get the opportunity to sniff the pipe, you might find that the knob doesn't work. That's usually a broken wire that requires resoldering, rather than a whole new box.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Checked the valve adjustments first thing this morning. Using a .005" gauge I found a couple intakes I set too loose, using a .009" gauge I found one exhaust too loose. I decided to use a larger gauge as a go/no go, if the large slipped in, then I'd further adjust. All the rocker springs were in place.

Rather than seek out the purple wire, I got lazy and just used the key. Took all of 20 minutes to check and set the valves. Sure beat all that wrenching .

When the valves were all set I cranked the engine over, about the time it reached 30PSI on the oil gauge, the oil tubes began running. Nice steady streams over each cam lobe, but what a mess from the oil running off the head hehe.

Once everything was back together, I hooked up the tach. Engine was idling at 600 RPM once warm. Turning the screw 3/4 counter clockwise raised the idle to 750.

As for the timing, well it was off. I noticed a prior tech had highlighted a second timing mark. Book calls for 5 ATDC (that mark is highlighted white from the factory?) but there was also a paint mark at 10 BTDC. If the vacuum line is disconnected, the second mark comes into view under the light (but was still off).

Setting timing to 5 ATDC (with vacuum advance hooked up)produced a loping/missing idle. Disconnecting the line and setting to the second mark produced a smooth even idle, and after reattaching the vacuum line, the timing advanced to ~2 ATDC. Idle increased to about 825, turning the screw clockwise 1/8 brought it back down to 750.

I decided to leave everything as was and see how it shut down. It shut down nicely with no run-on. Let the car sit for 15 minutes and restarted. Fired right up, idle settled down to 750 and was smooth.

Ran into town, the glass smooth feel is back, runs great at highway speed and idles nice at the stop lights (no wiggle at the antenna). No run-on or hard restart after getting to operating temp. The last thing I checked was listening to each injector through a screw driver. Yesterday #6 sounded different from the rest, today, after resetting everything, #6 sounds the same as the other seven.

By jove I think I've got it .

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Can anyone tell me how to hook up a meter to measure both dwell and RPM. I just purchased a Sears Tach/Dwell/Voltmeter and a light meter unit. Getting the light meter to work was not a problem but I was not able to figure how to get Tach and dwell to work. To measure dwell, I hook up the green clip to the positive side of the coil and the black clip to a bracket on the engine and set the switch on the unit to dwell and turn the engine over. There was no movement to the dial, none at all. What did I do wrong? As far as connecting unit to measure the RPM, I couldn't quite figure out how? Any help from you Mike, CTH, JIM, or anyone one else is appreciated.

P.S. If my dwell meter hook up was fine why didn't needle move?

Did you hook up the power leads?

I probably have your units grandfather. Red and black to battery, green clip to positive side of the coil (this is all one lead on mine). You should also have a magnetic clamp that goes over/around the #1 plug wire, looks like the pick-up from a timing light. That one reads the RPM. I doubt they changed much in 20 years so it should be similar.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

There are two kinds of meters. The old analog ones with 3 leads and the newer digital ones with only 2.

- For the 3 lead models, red & black go to +12v (battery post) and ground respectively. The green one clips to same place your points connection goes (see below).

- For the 2 lead models, black still goes to ground, but now the red one is used in place of the green.

Now the fun part. Figure out where the lead from the points winds up.

For a conventional ignition (just a black coil, single balast and a condenser), the wire from the points goes back to one side of the coil. Use the lead there.

If you have the transistorized ignition system (a switching module, two balasts, a blue coil), that means the points connect back to the switching unit. Rather connect right to the unit, there is a small junction post where the wire ends and that junction post has a very convenient metal tip on it. Clip onto that.

One uses the same wiring pattern for both tach & dwell. For both, the number of cylinders in the engine are important, since the frequency chain of pulses from the points gets divided by that number.

For dwell, the meter shows you the percentage of time the average pulse is "up" vs "down". For RPM, the meter tells you the number of pulses per minute. These are just different "averages" of the pulse train, since there are way to many of them to see individually.

An ignition scope actually shows you the pulse train graphically, with each successive set of pulses superimposed on one another. This tool is an immense help in diagnosing problems, but they are not cheap.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

The Tach/RPM meter that I have is an analog one (dial indicator) with only two leads. one lead/clip has a black plastic cover at end of it and the other has a green cover at the clip. So what do I have? It don't match any of your description CTH. For your info, I have a conventional ignition(black coil, single balast and a condensor) and as far as I can tell I made the proper connection. Any ideas why dial on meter did not move? could I have a short in the condensor or just a bad meter?

Then follow the 2 wire rules. Black to ground, green to coil where the points connect.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/