tacho problems

I have a tacho problem I hope someone can help with?
I run a Mallory Sprint Mag with 8mm pro wire leads and use a MSD tacho converter which is suppose to convert the signal from the mag so the Autometer tacho and shift light can read the signal.
The problem is the tacho seems to read the revs right at idle and low revs, and when the revs are brought up slowly but when the peddle is mached the tacho goes off the clock.
Any help would be much appreciated.
By the way I'm in Australia.

Brad.

 

Thanks for your reply Mike.
The Tacho worked fine on a normal distributor but with the mag it has never worked correctly.
I have the Tacho converter installed as per the instructions supplied. I have the signal wire connected to the positive side of the coil. I don’t have the MSD Inductive Pickup Cable.
Regards,
Brad

 

Hi Brad

Send my a scan of your instruction manuals - or exact part No - of the tach, converter & mag. Plus a sketch how you have wired all together.
To: krivan@dragracing.ch
With that info I hope to be able to help.

Dez

and ……let’s Dragracing

 

Brad671, switch to suppression wires and the problem will go away. If you can't switch for some reason, use a suppression wire on the coil to the mag at least. This will make it better, but not competely reliable.

I have been thru this on our car.

Rapid

 

Thanks Dez and Rapid,
I have a couple of things to look at now.
I have the converter wired in as pre the instructions for a Mallory Mag and I know the tacho works so I may have to get the suppression wires and see what happens.
Thanks again guys.
Brad.

 

almost all msd products will be adversly affected by solid core wire,use msd wires and the tack should work properly.solid core or poorly insulated wires discharge tons of rf.all that rf attacks things like signal converters and renders them useless.the switch to good wires worked for me.

 

brad... i've been there with the same set up you are talking about. and mine did exactly the same thing. hopped up mag III and tach converter to a autometer tach. i started by changing just the coil wire and didn't find much response. (everyone has a favorite brand but) i put taylor vertex thundervolt 50 wires on it (was running stainless mallory wires at first). after i switched... noticable pick in timing accuracy and smoothness of the motor and the tach is rock steady.

after you fix your problem i would suggest that if you go to a suppression wire (taylor's, msd's, whoever) look at them first if you have ANY variance in your ignition system as they are an expendable item (and the coil goes 8x as fast)

 

Talk to Mallory. DO NOT RUN A SUPPRESSION CORE WIRE WITH A POINTS TYPE MAG.

 

i HEARD the same thing googly is saying and mallory will tell you that it doesn't work or isn't a good idea... BUT if you want ANY kind of electronics to work i.e.; datalogger, tach, pacemaker, whatever... save yourself the headache and put suppression wires on it. have made a lot of passes with this set up both without a tach (solid wires) and WITH a tach (suppression wires)... not much time to look at the tach... but a shift lite is nice every now and then.

 

I will try the suppression wires and see what happens. Do you think I would notice any preformance drop?
I have tried to contact both MSD and Mallory about the problem and have had no reply.
I appreciate all the response I have had with this problem as no one in Australia seems to be able to point me in the right direction.
Thanks Again
Brad.

 

I am not disputing what Googly says. But, I have run all Mallory stuff until this year. We just bought a MSD 44. I have run the same Mallory Mags for the last 4 years with suppression wires. The mags always check good at the end of the year.

We ran a Mallory III, and Mallory IV. We always ran suppression wires. It was time to put new wires on the car, so we listened to the talk and switched to solid core wires. We then had all the troubles you are having.

Since the wires were the only thing we changed, I called my guy at Mallory. He said to run suppression core wire for the other electronics to work. We changed ours back and everything worked out fine again. I am sure it will solve your problems. I saw no et or mph gain with the solid core wires.

I hope this helps you out,

Rapid

 

I'm not saying it can't be done. But the first time you pull to the line and the motor won't fire because you killed the capacitor in the mag, you change the wires....Trust Me!
I was told that the extra resistance in the wire is very hard on the capacitors in the mag. The combination of the wires, .030 plug gap, and a fat load, we killed about a dozen capacitors in one year. I even started putting bullet connectors on the wire so that I could change the capacitor without re-setting the points.
We changed wires and solved the problem.

I would add some braided sheilding to the tack wires, and solve the problem.

 

Gap your plugs down to .018

 

We tried that too. The thing wouldn't run, sounded like a diesel truck. Opened the plugs back up and problem went away.

Oddball combination, I could go on... but why???

 

pretty simple really... if you want ANY KIND of electronics to consistently work on the car... run suppression wires.

if you want to run solid wires put a tach drive on it.

got a lot of laps on my car with suppression wires... no loss in power/et/mph with back to back laps with both kinds of wires... no mag problems. i checked many times because i was an 'old school skeptic' too

also on suppression wires. if the car ever acts up electronically/ignition wise CHANGE THE WIRES the are used up. they will most likely 'ohm' ok and look fine. the insulation on suppression wires deteriorates from the inside out


btw... if you run a datalogger with solid wires and you think your logger is 'bad' hit me up i'll take that p.o.s. off your hands for $100

 

Thanks to all those that replied to my problem.
I tried an old set of suppression leads I had and the Tacho seems to be working now.
SO thanks again it has saved me a lot of work and heartake.
But it poses a new question which leads are best.

Brad