MTFCA Forum

My 26 t has started running poorly. I actually wrote about this previously but after much tinkering I have no solution and more issues. The car doesn't have a miss but it isn't running smoothly and it seems to be getting worse. I drove about 30 miles yesterday and by the time I got home it was worse than ever. Today the starter will barely turn over to boot. My ignition switch, i assume is somewhat faulty because it will rarely run on its magneto even though the mag is good and puts out about 14 volts at idle. I mention the mag because for a short while yesterday I was able to switch over to the magneto and until it cut out again the car ran perfectly. Today I crank started it on the battery and checked the mag again and still good voltage so I wired the mag straight to the coil box. The engine was already warmed up but I couldn't get a single hit out of it. The coils are all freshly rebuilt, new generator, restored kingston carb, very old, likely original wiring, old but good looking roller timer, plugs are old but clean. I also bypassed the stock ignition switch with a toggle to see what that did but no change. I should also mention that the headlights on makes it run worse.

What am I missing?

Sounds like a bad or badly discharged battery - poor running, runs worse with lights on, starter grinds slowly are all symptoms

your mag/switch issue is just that, another issue

Do a load test on the battery. Most auto parts stores will do the test for free. Either way its a rule out.

I see you claim the coils are fresh. New caps? Were they tested & set on an ECCT.
How are the coil box contacts? Lots of spring & no carbon on the contacts. Are the outer terminal connections clean & tight.
Some replacement wiring harnesses had crimp only terminals. The can/will lose connectivity over time. They should be soldered.
These could explain why its not running on mag/battery & why its not running on mag, unless the mag is intermittent.

You might watch it run in a dark garage, looking for arcing.

colonelpowers wrote: ↑

Wed Apr 12, 2023 1:21 pm

My 26 t has started running poorly. I actually wrote about this previously but after much tinkering I have no solution and more issues. The car doesn't have a miss but it isn't running smoothly and it seems to be getting worse. I drove about 30 miles yesterday and by the time I got home it was worse than ever. Today the starter will barely turn over to boot. My ignition switch, i assume is somewhat faulty because it will rarely run on its magneto even though the mag is good and puts out about 14 volts at idle. I mention the mag because for a short while yesterday I was able to switch over to the magneto and until it cut out again the car ran perfectly. Today I crank started it on the battery and checked the mag again and still good voltage so I wired the mag straight to the coil box. The engine was already warmed up but I couldn't get a single hit out of it. The coils are all freshly rebuilt, new generator, restored kingston carb, very old, likely original wiring, old but good looking roller timer, plugs are old but clean. I also bypassed the stock ignition switch with a toggle to see what that did but no change. I should also mention that the headlights on makes it run worse.

What am I missing?

One thing at a time.
The starter barely turning over the engine. As they have said battery charging issue issue. While you have a new generator is it a new or old cut-out and what type solenoid or diode? If you have a fully charged "good" battery and the lights on cause the issue, poor running on battery, then that would indicate a wiring issue.
My ignition switch, i assume is somewhat faulty because it will rarely run on its magneto...I wired the mag straight to the coil box....I also bypassed the stock ignition switch with a toggle to see what that did but no change. Not sure when you bypassed the ignition switch with respect to wiring the mag strait to the coil box. And what the wiring configuration was that made things worse when the headlights were on.
..
So focus on running on the battery and forget mentioning the mag & eliminate it completely from the circuit & tests.
Start with a fully charged battery.
Using the dash ignition switch
- It should start without issue. The ammeter should show a slight negative reading.
- turning on the lights should cause the ammeter to go more negative but there shouldn't be any change in engine performance because its a fully charged battery
If you have problems as a result of doing the above - wire up the toggle switch & repeat the two steps.
--No problem then the switch or wiring to it may be the issue
--Still a problem then you have a wiring issue somewhere

yes one thing at a time...

but include in the list...
...a clean timer insides, no evidence of roller bounce

...make sure that in all spark position, no wire end/flag at the timer is able to arc to the block

...you say mag is 12V at idle, but won't start on mag...yet will run on the mag fine for a while once started on batt. ( Everything needs to be almost perfect to start on mag without spinning the engine but if you don't even get a belch...coils may be just a tad off? Find someone with an HCCT or ECCT to double check?)

...do check the fuel line etc. Just because, T's don't have a lot of spare left in a fuel supply and the least little thing can cause them to get a bit squirrelly.

...are you running spark and throttle in the correct sequence as you drive? Some will run in all conditions with the spark in one position all the time, others the combination of leaness of fuel and spark timing gets a lot more critical.

...do the toggle switch thing as recommended,,,be careful...that will tell you whether original switch or not. NEVER let the battery wire and the magneto wire become common, the mag dies a hard death.

...maybe even report what your spark plugs are and gap set? I know of many cases where setting the 25's at 025 is the absolute wrong thing to do...they typically run better set to 030 (or a thin dime as some say). Are your plugs sooty or clean? (Every little thing robs a bit...and sometimes they combine in a perfect storm.

...I'd also suggest checking the filter in the sediment bulb...just saying. Firsthand experience where a century of dust makes a Brillo pad 'crepe' that compresses while running, sputter stalls, then the 'crepe' relaxes and you think you did something right as it starts again good...until about 10 minutes later and it sputters again....

One thing I failed to mention and you may not know if this is your first attempt at hand cranking on MAG:

if your timer is CORRECTLY adjusted for safe battery hand cranking with the lever fully retarded, then unless you advance the timer lever 3-4 notches prior to cranking, you will most likely NEVER get the car started on MAG, as the timing for the MAG coil is way too far off for a spark to occur under sufficient compression to start. Some folks will "windmill" the engine and possibly catch the next "node" where a spark will occur and get the engine started, but that requires a lot of luck and immense effort.