MTFCA Forum

I’m driving my T more these days and what I continue
to encounter when I pull the plugs after a long
tour: no’s 3 and 4, clean. No. 2, fouled. No. 1
really fouled.
I am running a Stipe cam and a Prus high compression
head. I have tested the intake manifold for any signs
of a vacuum leak. No signs of a leak. Engine runs
strong.
Any ideas guys. Thanks.

Are you using the hot air pipe on the carburetor... Plug gap?...

Do you have any kind of auxiliary oiler on your car? Compression even?

Too often, people fret over the appearance of plugs. Don't worry about your plugs as long as the engine performs well. No. 1 most often looks sooty. No big deal.

Thanks. I’ll breathe a little easier now.

Fouled with what? Fuel, oil, soot? A little information would help. 3 deposits 3 different causes.

Craig B ;
All Model T's have the same problem.
You can read that in:
The model T FordOwner The best of Murray Fahnestock
page "304-305
Toon

My No1 is also usually sooty. Does that mean I shouldnt pay much attention to it?

CraigBothwell wrote: ↑

Thu Jul 11, 2024 7:24 pm

I’m driving my T more these days and what I continue
to encounter when I pull the plugs after a long
tour: no’s 3 and 4, clean. No. 2, fouled. No. 1
really fouled.
I am running a Stipe cam and a Prus high compression
head. I have tested the intake manifold for any signs
of a vacuum leak. No signs of a leak. Engine runs
strong.
Any ideas guys. Thanks.

Generally that is because it runs the coolest, what with being right next to the fan. You can try tweaking your carb adjustment just a bit to lean it down some and after cleaning your plug, run it around 20-30 miles and check it again. For all the complaints people give/gave TruFire anyway, on my former '20 I was able to tweak it to where #1 plug was as clean as the others. Oddly, on my other cars with stock ignition, I have them almost as clean but not as good as that one was. And like they say, no two T's gonna behave the same anyway. Just my thoughts and experiences.

Soot, a dry black deposit, is usually caused by too much fuel.

Quelenrir wrote: ↑

Fri Jul 12, 2024 8:04 am

My No1 is also usually sooty. Does that mean I shouldnt pay much attention to it?

I wouldn't think of looking at spark plugs as long as the car runs well.

Charlie B in N.J. wrote: ↑

Fri Jul 12, 2024 8:57 am

Soot, a dry black deposit, is usually caused by too much fuel.

And by the fact that these are 100 year old, inefficient engines, with imperfect fuel delivery.

Over-oiling will cause #1 and #2 plug to accumulate deposits, even in a very tight engine with modern style rings. Adjusting the crankcase oil level or the auxiliary oiler, if present, will correct the problem, assuming the engine is in good condition and in good tune. Plugs should run fairly clean on a long tour in a tight T engine. My plugs stay clean all the time, but I don't idle the engine much or drive in stop and go traffic, and I usually drive well over ten miles whenever I start the car. I keep the oil level halfway between the upper and lower cocks, and have a Texas T auxiliary oiler with a restrictor to limit the oil delivery to a rate the rings can handle. The Texas T oiler is capable of over-oiling a T engine. I use 10W30 full synthetic oil and regular pump gasoline, ECCT tuned coils, and a New Day timer.

Quality modern motor oil and detergent gasoline go a long way toward limiting combustion chamber and crankcase deposits in early engines that are in good tune and overall good condition. "Carbon removal" was once a fairly regular maintenance procedure. It's rarely, if ever, necessary using modern gasoline and motor oil.

TXGOAT2 wrote: ↑

Thu Jul 11, 2024 8:25 pm

Do you have any kind of auxiliary oiler on your car? Compression even?

Hi volume external oiler & overfilled crankcase. #1 plug worst. #2 a bit dark. #3 & 4 pretty clean.
Runs like a molested monkey with a 280 super cam & Prus head. No power or speed loss complaints.
Heat pipe not on YET. Intake elbow ice cold. High humidity here near the coast.
Heat pipe recommended. A little top end loss with it on, but when it was on it still topped out @ 60.
Thats a satisfactory loss for this gentleman.

A limited reduction in the oiler flow and keeping the oil level at or below the top cock may be enough to keep all plugs clean. I limit my speed to about 45 MPH. Excess oil does no good, and may foul plugs and cause heavy deposits in intake ports and on intake valve stems and heads. Obviously, under-oiling is to be avoided. Excess oil flow to the front of the engine may aggravate any tendency to leak oil. Too much oil in crankcase can cut power due to drag on the crankshaft.

Sometimes we think a little soot or etc is bad business in a T. Maybe or maybe not but if it’s running good and no noticeable miss I wouldn’t worry about it. It is a Model T you know.

A T with stock rings will probably pass enough oil to keep plugs a little "dirty", especially if the oil level is too high and it is driven slowly.

John kuehn wrote: ↑

Fri Jul 12, 2024 1:22 pm

Sometimes we think a little soot or etc is bad business in a T. Maybe or maybe not but if it’s running good and no noticeable miss I wouldn’t worry about it. It is a Model T you know.

YES!!!

2 clean plugs and 2 fouled plugs and you guys say forget it. There’s something going on. Now if the owner doesn’t want to be bothered with it that’s OK but something’s going on and it’ll bite him in the butt sooner or later.

Is head gasket on right? There is a front and rear to them. Dan

Charlie B in N.J. wrote: ↑

Fri Jul 12, 2024 4:08 pm

2 clean plugs and 2 fouled plugs and you guys say forget it. There’s something going on. Now if the owner doesn’t want to be bothered with it that’s OK but something’s going on and it’ll bite him in the butt sooner or later.

The plugs are not fowled in the sense they don't fire, they are firing fine. 2 front are blacker more than the back 2.
There is no performance complaint. Runs very smooth.
The head gasket is on correctly. I cant see how that would pertain to darker plugs either way.

I use Bosch platinum plus self cleaning plugs . The never get fouled or sooty , and I have run the same set of plugs for years ????

Head gasket on backwards will cause two front cylinders to run cooler and back two to run hotter. Have seen it a few times.