Digital handheld dwell meter and tach for MSD

[pope]

HELP!

I am really getting fed up with this. As I've said in some other thread I have a handheld digital tach



It was working fine until I installed an MSD 6AL, MSD high vibration coil and the MSD tach adapter (8910). Now its readings are all off. I'm assuming it's because of the multiple sparks that the MSD is firing.
I proceeded to buy an 'automotive analyser' (PDF) so I could also do dwell measurements. I thought that it would work since it gets its reading off of the points (reportedly).

****ING thing doesn't work. I put the black on ground. I put the red lead on my distributor terminal (points) and the reading is all over the place, so quickly that you can't read it. I put the red lead on the (-) terminal of the coil and the reading is like 60 rpms !

I tried with the dial on different number of cylinders too. No luck. It HAS to work somehow, this stuff isn't rocket science. Pleeeeeeeeease. I'm exasperated.

[rick-l]

Why do you care about dwell with an electronic ignition?

[Paulporsche]

Rick,

There was a recent thread on this. Even w/ CDI and points, a change in dwell equates to a change in timing. As the point gap decreases, and the dwell angle increases, the timing retards.

Also cars w/ lambda control can set their mixture using the meter.

Pope,

I don't know about MSD and digitals, but, can you get ahold of an old style analog dwell meter? They should be accurate enough and work w/ the MSD. I've had one from Sears for 35 years. You can center the needle and then go from there. As you might imagine, I have no idea about where to get one in Romania.

[rick-l]

Originally Posted by Paulporsche

There was a recent thread on this. Even w/ CDI and points, a change in dwell equates to a change in timing. As the point gap decreases, and the dwell angle increases, the timing retards.

Yes but if you set the gap (length) and then the timing a few degrees of dwell won't make a difference will it?

Originally Posted by Paulporsche

Also cars w/ lambda control can set their mixture using the meter.

Is that measuring the duty cycle of the regulator?

[Vintage911Racer]

Just buy a cheap Autometer tach and plug it into your MSD Box (assuming you have a terminal on the MSD for the green tack wire to plug into) and yuo will have a perfect reading and not have to run the tach adapter either.

[Paulporsche]

Rick,

You are right in that the dwell is not as critical as in non CDI cars. Probably there are many people out there who use a feeler gauge rather than a meter and get satisfactory results. You still set the dwell and then the timing as you said, so there is room to maneuver. It's more a question of "why not set it within design spec?" rather than something else. And then, as the dwell changes, either accurately reset to spec and/or adjust the timing to always keep performance optimal.

There is a port to which the meter can be attached to set what I think is called the "duty cycle" which should be around 58 degrees @ idle. I don't have one of these on my car so I've never done this. If you search psalt and dwell and mixture he has explained this in another thread.

[911pcars]

Since dwell is less important with CD ignition, I'd just set point gap with a feeler gauge, then inspect it periodically. What's more important here is the ignition timing. Trade in the dwell meter for a timing light, one with an advance knob to track distributor advance.

Sherwood

[pope]

Originally Posted by Vintage911Racer

Just buy a cheap Autometer tach and plug it into your MSD Box (assuming you have a terminal on the MSD for the green tack wire to plug into) and yuo will have a perfect reading and not have to run the tach adapter either.

Sorry but I'm not sure I understand. Why would I not need a tach adapter? My dashboard tach doesn't work without it.

And if a cheap Autometer tach would work, why doesn't this not-so-cheap 'analyser' not work? You must understand how uncomfortable I feel in ordering a cheap tach if this doesn't work.

[911pcars]

"****ING thing doesn't work. I put the black on ground. I put the red lead on my distributor terminal (points) and the reading is all over the place, so quickly that you can't read it. I put the red lead on the (-) terminal of the coil and the reading is like 60 rpms ! "

Your photo of the tachometer is a separate issue from your dissatisfaction with your engine analyzer. Since most vehicles now use electronic sensors in the ignition system, the older-style analyzers for inductive ignitions no longer applies. Such is the case with your Draper tach/dwell functions. They rely on the primary voltage signals on earlier inductive ign. systems.

Breaker point, inductive ignition systems have been superceded by electronics since the 60's-70's. Breaker point, CD systems are not the same.

From the pdf manual you included:
- TACH (RPM) MEASUREMENT:
- IMPORTANT: For detailed and concise information on the correct use of this tool always refer to the vehicle manufacturer’s service handbook.
1. Connect the red test lead to the ‘V/ ’ jack socket and the black test lead to the ‘com’ jack socket.
2. Set the selector switch to the desired TACH range.
3. Connect the red test probe to the breaker points or the ‘-’ terminal on the ignition coil.
4. Connect the black test probe to the ‘-’ terminal of the battery or ground. Refer to Fig.1 on page 7.

Use the Draper meter for its multimeter functions. Don't use the tach and dwell capabilities that don't apply to your vehicle.

Sherwood

[pope]

Thanks for your input once again Sherwood.

I think the only way I can get the tach part to work is to connect it to the 'tach output' of the MSD. Its reading there looks true. The dwell will probably never work as you said.

Anyone have any urls to a good timing light that would work for this setup?