MTFCA Forum

Sadly, with my magneto no longer operational, I'm now resigned to driving my T on battery only going forward. Other than making sure I have a good battery with sufficient charge, what other things do I need be aware of driving this way? Thank you in advance for your help.

John, just make sure you switch to the battery position on the switch!

Allan from down under.

...and you can drive on battery in reverse, too




sorry...couldn't help it

You can drive just fine on battery. Many cars did for many years. If your normal top speed is under 40, you can still reach it but it will be a bit slower and may not seem to have the same power. You may have to pay a little more attention to adjusting the spark lever, but it will run fine.

I have run my truck on battery for years. I have a separate 12v battery (the lights, starter, horn etc still run on 6 v) wired to the 'MAG' position and keep the 6V still on the 'BAT', that way I can be sure of always having spark!

The 12V is 'total discharge' - meaning it is not hooked up to a Generator, however, even on the longest runs over several days I have never had an issue with the 12 V going flat.

I keep the 12V topped up with a battery tender and have never had a problem yet, but do give it a boost on the charger now and again.

The 12V gives a better spark than 6V battery (the magneto kicks out 38V so there is no issue running 12V through the coils). Switching from 'BAT' to 'MAG' (6V to 12V) makes a noticeable change in performance.

All the best,

Adrian

As Mark says, the spark lever may need more adjusting.
Eventually the engine or the transmission will decide it's time for a tear-down. That will be an opportunity to fix the mag.

Thank you for all your assurances. Happy driving!!

You didn't say what year T you have and if it's equipped with a generator. If it has an operational generator (or alternator for that matter) all you need to do is put the switch n the "BATT" position. If it does not have a generator, be sure you keep the battery your using charged. When I first got my TT running after many years of sleep and not having everything working properly yet I used a 6 volt dry cell battery. It's surprising how long those things last, but be sure to keep a spare handy.

I can't drive ON my battery - it is too small.

Sorry I couldn't help myself!

Along with less engine performance from hot spark with the vibrator coils running full time on such 6v or 12v DC current, coil points will carbon arc and wear faster.

Those trembler coils and points were made for magneto AC juice

Of course what Dan said above is true. Running on DC will cause the points to wear faster than AC as the metal begins to transfer in one direction whereas (as anyone whose played with more modern systems will know) you get a pit on one point contact and a raised section on the other. Since you have no mag the point is moot. No pun intended. Drive/enjoy.

IF I HAD THIS PROBLEM I WOULD INVEST IN A DISTRIBUTOR, BOSCH MADE A GOOD ONE, AND YOU CAN RE SELL IT WHEN ITS NOT NEEDED. ALSO THERE'S A SHIM YOU CAN PUT IN THE REAR MAIN TO TAKE UP THE MOVEMENT ,

Dan made a good point. "Quick fix" is swap polarity on the old battery now and again, and keep those points clean.
Given usual T mileage, that has not been an issue for me (yet)

John, You have the perfect time to get an ETimer and then your car will run better than what you were experiencing before your mag quit. I'm surprised no one else has offered that fix for you.
Richard offered the conversion to a distributor which was a common solution for a inop mag but the ETimer maintains the original T equipment and out performs the Dist system.
Do yourself a favor and check out Mike Kossors E Timer and you'll never regret it or want to give it up.

After about 41,000km of driving over the last 17 years with only 6V, I'm still waiting for the points to wear out. And, top speed is around 75km/h on the freeway. It's all how it's set up.
However, coils I've restored for those who use them on 12V do have a shorter point life. You can tell the 12V users by all the black marks around the points.