MTFCA Forum

I run on a 12 volt battery because of a weak magneto. My car runs good but can be hard to start. Right now I have Motorcraft plugs set at .032. Would a smaller gap make the car easier to start?

When I purchased my first T, a '13, I found that I absolutely could not start the car using the Motorcraft plugs in it, nor new Motorcraft plugs purchased for it. I installed new Champion X plugs and it started and ran. I then put in restored original X plugs and it started easily and ran a little better. Those plugs have been in the car for over 12 years now.

The previous owner had to tow the car every time he wanted to start it and I assumed I had a fair amount of engine work to do when I bought it. As it turns out, not a single bolt or nut has been taken off of the car with the exception of replacing the bands and eventually rebuilding the carb.

Full disclosure: this is a tired engine which runs fine but is still, a very old engine. Many have run Motorcrafts successfully, but I suspect that their compression is much better than this engine. In mine, they simply will not light it off.

I have no experience with the Motorcraft plugs, I alway have Champions X in the cars.
For the hard starting I think you should open the spray needle a 1/4 of a turn to start it.

Just my opinion.
Andre
Belgium

I know your question is about plugs but my car's starting idiosyncracies may be illustrative.

Depending on the starting procedure I use, my car either completely resists starting, or starts so quickly that people comment on how well it starts.

The only way it wants to start is for me to leave the key in the off position, then turn the engine over two or three times with the choke pulled out. Then the key goes to battery, ignition retarded, throttle more than halfway open and hit the starter. It jumps to life...typically doesn't even make a full revolution.

Then I immediately give it some more timing and back off the throttle to an idle and off we go.

Fail to do it that way and you'd think something was wrong with it.

Some modern plugs may have a resistor built in to suppress RF interference, or they may have a gap or carbon insert in the center electrode to act as a heat dam to allow the plug to run in the proper heat range for a modern engine. Stock T ignition systems run at far lower voltages, especially under starting conditions, than systems designed since WWII, not to mention systems designed in the early 1970s and later. While Model Ts have much lower compression than typical modern engines, they don't have the same level of fuel mixture control and oil control as late model engines do, and they are far more likely to deposit soot and carbon on the spark plug due to low combustion pressure, large combustion chamber area, low rpm operation, and low combustion temperature and velocity as compared to modern engines. These factors combined with the low system voltage make for conditions rather different than those found in a modern auto engine. I would expect to get the best results when using a stock system on a stock engine by using plugs originally designed for the Model T and setting and maintaining them as directed by Ford. FWIW, my car has silvery-plated Champion A-25 plugs in it, and it starts easily on the 6 volt battery and runs well on battery, and better on MAG.

I am running a 12 volt system, no mag. I tried modern Motocraft plugs w/adapters, always getting a lot of soot. Installed Champion #25 plugs w/ .025 gap, runs & starts well,with very good color on plugs. I think the heat range is closer to original specs. Hopefully this helps you.

I run both my t's off a 12v battery and have no issues starting with the standard plug gap. Not even sure what plugs are in the cars, one has a Anderson timer and the other a I-timer. With the I-timer I can slowly crank the car over and it will fire right up.

Standard plug gap for my Champion X's with the ignition system running from 6V. Easy starting and good top speed.
I'd say there's something else causing difficult starting.

OP: "Right now I have Motorcraft plugs set at .032. Would a smaller gap make the car easier to start?" I would expect that a smaller gap, such as .025, would improve starting, assuming you have a stock system in good condition. A 12 volt automotive battery in a good state of charge should provide plenty of power to operate the ignition system. In the Model T era, cleaning spark plugs was routine maintenence.