Electronic Ignition -Adjusting the Carb, with a dwell/tach

[Pawned]

If this has been covered on this board, I did not find it.

I have a OLD Sun Dwell/Tach that I have been using to adjust carburetor. Connect to the - side of the coil and ground. It worked wonderful, that is until:
I put in an electronic ignition and when I try to set the idle the dwell/tach does not work.

Question: How do I hook up an "old fashion" tachometer to set the idle when I have converted to an electronic ignition?

I read something about connecting the tach to the gray wire from the control box

Thank you in advance for your help.

 

[TrailBeast]

It shouldn't matter much at all that you have electronic now.
Most tachs run off the coil negative anyway, so just hook it up like any other tach.

Don't make me come down there.

I have a cheapie tach that works fine with electronic ignition connected to the coil negative terminal that I won't be using in the car. (And it works with my HEI)
You are welcome to it if you can use it.

 

[Pawned]

It shouldn't matter much at all that you have electronic now.
Most tachs run off the coil negative anyway, so just hook it up like any other tach.

Don't make me come down there.

I have a cheapie tach that works fine with electronic ignition connected to the coil negative terminal that I won't be using in the car. (And it works with my HEI)
You are welcome to it if you can use it.

It is my understanding that the electronic igni coil produces a much hotter spark. It may be why the meter does not work now.
I was thinking about putting the old ignition back in so I can adjust the carb and then switch the parts back.
As I am sitting here thinking the hotter spark is not produced on the - side of the coil, It goes to the distributor cap.
Maybe my dwell/tack just bit the dust

 

[TrailBeast]

It is my understanding that the electronic igni coil produces a much hotter spark. It may be why the meter does not work now.
I was thinking about putting the old ignition back in so I can adjust the carb and then switch the parts back.
As I am sitting here thinking the hotter spark is not produced on the - side of the coil, It goes to the distributor cap.
Maybe my dwell/tack just bit the dust

:-D You are correct.
Tachs get thier signal from the intermittant ground signal off the coil and are not involved in the spark at all.

The meter probably bit the dust.

 

[67Dart273]

Well WHAT KIND of electronic ignition? CD (as MSD) will not trigger a tach, as it works completely different. Most "switched" ignitions, IE HEI, Pertronix and Mopar ECU should trigger a conventional tach

 

[TrailBeast]

Well WHAT KIND of electronic ignition? CD (as MSD) will not trigger a tach, as it works completely different. Most "switched" ignitions, IE HEI, Pertronix and Mopar ECU should trigger a conventional tach

Yep, and he did mention a grey wire that he read about.
I can't look it up right now, but maybe for his ignition that is the tach wire.

 

[Pawned]

Distributor, control box and ballast is Mancini. Coil is a MSD 8203?
Mancini racing is Mopar Performance

 

[67Dart273]

Well hell it should work. Any chance you accidently switched coil wires + / - ?

 

[Pawned]

I was about to start typing when I went back in the garage and rechecked the wires. They are correct.
So, riddle me this Batman, the two large old tach/dwells the needle does not get off zero.
But the little gray plastic piece of garbage, works perfectly.

Maybe they built the gray crap with technology to handle Electronic Ign.

 

[67Dart273]

I'd be checking the oldest one for a battery.

Some of those (Heathkit) hook to coil neg and coil POS, and not to ground

Here, this appears to be you old one

[ame="http://www.youtube.com/watch?v=Z0R9dIJlg-o"]Dwell Angle and Tachometer- by Accurate Instrument Company (circa 1967) - YouTube[/ame]

Destructions for one Sun / Actron model

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&ved=0CGQQFjAG&url=http%3A%2F%2Fwww.actron.com%2Fmedia%2Fusermanuals%2F7673-91%2520PW%2520CP7673_Inductive%2520Engine%2520Analyzer_MNL_Eng.pdf&ei=imoJU5vrGZKCogSYpIHgAQ&usg=AFQjCNHjyKHicd8g5kS-yGztUCkNF0NypA&sig2=gMB7Nqfyhrpi7WpWgfJzXw


There's some various here at Actron

http://www.actron.com/user_manuals_disc.php

 

[Pawned]

I'd be checking the oldest one for a battery. I HAVE The Sun lower left, I'll go look

I looked in the Sun, there is no battery. No battery in the other one. No battery in the gray plastic piece of junk

 

[BillGrissom]

My old Craftsman dwell/tach meter works fine with my Crane Cams XR700 electronic ignition. I wonder if it would work with multi-spark ignition like Pertronix Ignitor III.

 

[Pawned]

I just now got off the phone with Mancini Racing tech line.
The guy I talked to says this is the first he had ever heard of such a thing. He went to ask another person there and he said that the OLD tach/dwells will not work with the new electronic ignitions.
I ordered a newer Tach/dwell that should be here in a day or two. It was made in 2004.
He said that should work properly. The newer units have circuitry that accepts the electronic ignitions.
Hopefully, problem solved. I will let you all know when the new unit gets here, if it works.

 

[Pawned]

I just got my new tach/dwell, it says on the package for electronic and conventional ignitions. but due to a grave screw up the car does not have a fuel tank.
So I may just put the gas can under the car and stick the hose into that.
Patience is not one of my virtues

 

[TrailBeast]

I gotta ask, what was the grave screwup?

If you don't want to say it's ok.

 

[Pawned]

I was putting it up on jack stands, the jack was still pumped up as I was pulling it out from under the car. For whatever reason the jack stands slipped and the can came down, really fast. The jack was under the gas tank when it fell.

 

[TrailBeast]

I was putting it up on jack stands, the jack was still pumped up as I was pulling it out from under the car. For whatever reason the jack stands slipped and the can came down, really fast. The jack was under the gas tank when it fell.

Well that sucks.

 

[Pawned]

I just got my new tach/dwell, it says on the package for electronic and conventional ignitions.

The tach/dwell I got is a Actron CP7605 Dwell/tachometer and what a sorry piece of trash it is. I returned it to Amazon the next day. The resolution is non existent. I thought the tach was dead as it did not move when I started up the car. When I revved up the engine, then it started to move.
The space on the dial between 0 and 2k rmps is all of 3/8th of an inch. So much for setting the idle.
Looks like I will have to buy a digital read-out tachometer if I want to tune the carb.

 

[halifaxhops]

I was putting it up on jack stands, the jack was still pumped up as I was pulling it out from under the car. For whatever reason the jack stands slipped and the can came down, really fast. The jack was under the gas tank when it fell.

Was it on Graveyard Cars?
Feel your pain!

 

[Pawned]

Was it on Graveyard Cars?
Feel your pain!

No, I do not think so. Actually if it did not fall I would not have found the rust problem in the trunk.

 

[halifaxhops]

Funny how things show up!

 

[Pawned]

Well, it has now been well over a year and I addressed this problem once again.
I hooked up the large gray one and lo and behold it is reading RPMs once again.

curiousier and curiousier