I'm new so please be gentle. I have a '23 touring with an aluminum high compression head. In inspecting my spark plugs I noticed the number one is sooty and the other 3 look perfect. I have replaced that one plug with a matching Champion plug and have been running it for the last month. This morning I pulled the plugs and #1 is sooty again, the others appear fine. Suggestions?

Soot could be from it being rich (Fuel or a colder running cylinder for whatever reason) or a bit of oil. A compression test would give some information.

I have seen from past posts on the forum that #1 runs cooler than the other cylinders, hence the propensity to foul.

There's no harm in running a hotter plug in the #1 cylinder only. Do a Google search for "plug chart MTFCA" and see if you can find a plug chart that shows what plug is one or two steps hotter than the one you are currently using.

"Looks Sooty" does not mean you have a problem. Is the #1 plug fouling before the others - or - is the engine running fine and you are worried when there is not actually any problem?

My #1 plug is always a little more sooty than the rest. I have heard this is normal as the #1 cylinder gets more cooling due to the cool air from the radiator air stream.

Jason,

This is true, especially if you let the engine idle a lot. If you shut the engine off as soon as you are done driving then all the plugs will look the pretty much the same. Long periods of letting the T engine idle are not good. Just don't do that.

At stop signs or lights or in a parade, keep the engine at a fast idle.

Royce,
You hopefully have accurately described the problem. The engine runs like a top and being a newbie I assumed the plugs should all look alike.

Back when I used a conventional model T carburetor I ran a remote line from a lever on the steering column to the needle valve adjustment on the top of the carb. Made it very easy to lean out the mixture as the engine warmed up while driving. It was so easy to start out rich and dial it down.

The no-name updraft I now have on my speedster is great but the needle adjustments are not as easy to set up that way, so the safest setting for the valves is a richer mix .. causing some carbon .. out the exhaust and on the plugs. So I clean the plugs more often. Need one of those glass spark plug cleaning tubes. :-)

By the way, welcome to the Forum John.

Regards,
Garnet

John, you didn't ask about this, but it's for folks who are new to Model T's.

http://dauntlessgeezer.com/DG80.html

And another: http://dauntlessgeezer.com/DG79.html

There are other pages you may find useful at the same address.

Thanks Steve for your input. I have "surfed" Dauntless Geezer and learned bunches. I also have these manuals on a disk. I suppose I could spend a little more time studying them.

You didn't say whether or not you are running a water pump. With a water pump you will have coolant flowing through the engine and radiator much faster than without one. The most direct route between the water input and output is past #1. The original system depends on thermosyphon. With thermosyphon the coolant raises as it heats up and settles as the radiator cools it. The engine will run at much more even temperature if it uses thermosyphon.

If your spark plug is dry sooty, you are running a bit rich. If it is oily sooty, you are burning oil.
Norm

Thank you Norman. No I'm not running a water pump. The "sootiness" is dry so I guess I'm running rich. I'm going to address that issue next. Thank you so much for your help.

The reason number 1 and number 2 cylinders tend to run rich in a Model T is due the way the carburetor and stock intake manifold are designed.
The gasoline enters the air stream at the bottom of the air channel in the carburetor. The gasoline does not fully atomize with the air, and the rich mixture flows up the lower curved surface of the manifold and into the front cylinders while the leaner mixture flows into the rear cylinders.

The fan and cooling water do not make any perceptible difference. The can not change the mixture once it enters the cylinder of a running engine.

What brand and number plug ??? Champion X, AC, modern ???? makes a difference.... heat range.

Are you running the hot air pipe? (aka Stove) If not you could try putting one on, might help.

Hi John,

Welcome to the forum. I haven't read all the posts above so forgive me if this has been mentioned already.

What you describe is very common and basically a "normal" tendency for Model T's. Lot's of people ask about it and wonder if it's a problem. It's only a problem if it creates a misfire. If it gets that bad try leaning out your mixture a bit. Otherwise, it's something you can just ignore.

Is your head gasket on backwards? That will cause this. Dan

Thanks everybody. I adjusted the fuel mixture and found the engine ran better with 1/4 turn to the right or more lean. I have run the car for a couple of weeks and looked at the plugs today. Presto!! Nice and clean! While driving I have notices some minor "popping" which from what I've learned my be a sign it's too lean. I have now adjusted to the left 1/8 turn and I'll see what happens. Your advice is priceless.

Sounds like you're zeroing in on the optimum setting, well done!