MTFCA Forum

Has anyone else noticed the #1 cylinder of their engine running rich? I regularly check my spark plugs because they're a good read on how the engine has been running. #2, #3 and #4 plugs looked great; no oil or carbon, burn mark about 1/2 way down the ground strap, etc. But #1 plug had carbon build-up (not oil). It wasn't fouled but definitely not as clean as the other three.

All new plugs (Motorcraft) gapped to .032". New coils (rebuilt by Ron Patterson). Swapping plugs/coils, the problem doesn't follow (#1 still rich). I don't think it's an intake leak; the front intake port feeds both #1 and #2 cylinders (#2 plug is fine). Verified all valves are lashed to .010" intake and .012" exhaust (new, oversized 350 Chevy valves, hardened valve seats and adjustable lifters). All the wiring is new; coil box rebuilt with composite material and new contacts (didn't think either was the cause but trying to be thorough). Exhaust manifold is new and the machine shop checked the side of the head for flatness.

Engine runs and idles great; no misses or stumbling. I regularly get free starts.

Searching the forum I found one opinion that #1 cylinder tends to run slightly cooler, because it's right behind the water neck. Thus incomplete combustion and the resulting carbon build-up. I suppose another possibility is the machine shop didn't get one of the valves on #1 seated properly/completely.

Any ideas? Is it just another "Model T" thing, like leaking oil? It's not causing a problem, I'm just trying to figure out the cause.

Does this engine have any type of auxiliary oiler?

Also: According to Ford, Model Ts perform best with the oil level halfway between the upper and lower oil check cocks on the oil pan.

Check oil after the car has sat for half an hour or more and with the car sitting level.

To me, your post comes at a good time.,.. The last time I put new plugs in was 10 years ago and I've been running it ever since with no problems except for the past 2 months or so where I have felt it was running minus a cylinder or two till the engine warmed up. I've also been running with out the hot air pipe. Took those plugs out this afternoon and found... Number 1 plug and number 4 plug are dry and black, 2 & 3 plugs are grey. Before I put a new set in, do you think I should also put the hot air pipe back on?..

I'd try the hot air pipe. Winter is approaching, and it won't do any harm, and it just might help.
An engine that is over oiling for any reason might be expected to have more deposit on #1 and # 4 plug.

Deposits could also result from the amount of* use on the plugs.

Reducing the gap just a little might improve their function enough to get them to run a little cleaner, though replacement or cleaning and filing is due at high mileage* anyway.

To address your concerns about a valve not properly seated, check the compression on each cylinder.

Art Mirtes

Engine runs and idles great; no misses or stumbling. I regularly get free starts.

There's your real test. Leave the plugs alone

Gapped at 0.025", been in use 10 yrs. , possibility of too much oil, and no hot air pipe...... Before I put new plugs in, I will change the oil - 10W30 Mobil 1, shy of 4qts. , and install hot air in intake pipe.

10,000 miles used to be the suggested service life of spark plugs. Years in service don't matter.
The severity of service and the requirements of the engine* do matter.
* Working pressures and the condition of the ignition system will also affect how much plug wear, deposit accumulation, and gap error an engine will tolerate.

Re:

"...except for the past 2 months or so where I have felt it was running minus a cylinder or two till the engine warmed up"


That sounds like something a heat pipe would improve.

Barry P.
All Model T's do that , You can read that in :
The Model T owner the best of : Murray Fahnstock
Pag. 303 - 305

Toon

The last time I saw this situation, the motor had a slight intermittent miss. I tested with a champion plug tester under pressure. The plug skipped a spark occasionally. Closing the gap .003 more to .024 caused consistent firing under pressure test.

The topic of this thread keeps reappearing, so there apparently are some problems to be addressed. I have controlled carbon on #1 by adjustment of the needle valve. In summer warm air the car can run just a tad richer without carbon build-up, helps keep the engine cooler (trick learned from long-time Model T guy in Virginia). In winter I run just a bit leaner, helps with the carbon on #1 and with much cooler weather to car runs cool anyway. We are talking here about maybe an eighth of a turn on the carb control knob from one extreme to the other. I have tried to avoid the manifold heat pipe as some dynamometer tests reported on several years ago here indicated a 10% loss of power with the heat pipe installed.

Also: According to Ford, Model Ts perform best with the oil level halfway between the upper and lower oil check cocks on the oil pan.

Given the quote above I copied/pasted from a previous post...just begets one question: HOW are you supposed to know it's halfway between the two!!! Unless you use those otherwise worthless site-glass things you can't!! And they almost always end up leaking, ask me how I know!!

Guys, thermo siphon works, but results in un-even cooling. The front of the engine will always be cooler than the back. I've installed a 160 degree thermostat and now the engine is constant temp front to back and no carbon build up on the plugs.

My car has a dipstick accessory that works well. To check the baseline oil level, I put the car on a level surface and took out the top cock on the pan and used a bent wire to check the oil level. I marked the dipstick when the level was halfway between. Model T oil pans don't all have exactly the same capacity. Unless you are in very hilly country, or driving in a race, it's best to run the level just above the lower cock. Don't use thick oil. Auxiliary oilers are a good thing to have, but some of them can over-oil the engine. In that case, the oiler can be adjusted to lower the rate. That can make the difference between an engine that oils the # 1 plug and smokes, and one that does not smoke at all and shows even color on all 4 plugs.

Model T engines need to run at 180 F to about 200 F at the water outlet. In colder areas, the engine might run cooler than that. Blocking the lower 1/3 of the radiator with cardboard will usually cure that, but it's best to have a temperature gauge if you do that. A thermostat can be used, but they are usually used with a water pump. A thermostat should have a 1/8 or 3/16" bypass hole drilled in it when used on a T, with or without a water pump. That will allow any bubbles to escape, prevent hot spots, and assure that hot water actually reaches the thermostat sensor as it should. A 180 F thermostat ought to work well in cold country.

They run warmer in cold weather without a water pump. The fluid will circulate with the hot water rising and drawing in the cold. So as the engine warms up it will circulate faster. With a water pump, the coolant will circulate as soon as the pump starts turning which happens right when the engine starts. I found this out when I took one of the first tours in my first T. We went up into the mountains where there was snow on the ground and stopped for a break. Everyone was standing in front of their radiators to keep warm. I found that my radiator was cold because of the water pump. So even if you use a pump in hot weather, take it off and use a straight hose on the inlet to the engine. That way you won't need a thermostat.
Norm

I'm lost on the #1 cyl. running cooler because it's nearest the water outlet? Isn't the water passing #1 cyl. heated by the other 3 cyl.'s?
A compression test is a good start but have you tried swapping plugs & coils around to make sure it's not one of them?
Craig.

If the car runs great, with no apparent issues, then fretting over sparkplug carbon is just way overthinking things.
It's an inefficient, low compression engine, with unequal fuel distribution and cooling. It's gonna make carbon.

Tim, this is how Steve Jelf checks oil level. He only opens the petcocks to check the level then closes them.

BE_ZERO_BE wrote: ↑

Wed Nov 29, 2023 3:55 pm

Number one cylinder is right behind the fan so it runs cooler than the rest.

Some previous discussions about this.

https://www.mtfca.com/discus/messages/2 ... 1171848291

https://www.mtfca.com/discus/messages/8 ... 1253843776

https://www.mtfca.com/discus/messages/5 ... 1426657192

Has anyone ever proved that with a temp sensor?

When Model T engines were running in dirt track racers, they had a blank of plate in front of #1 to keep the fan from cooling it.

That plate was about 4 X 6 inches an I had one at one time, but I could not find it now.

When I first got a Model T, I noticed one plug would often fail when touring.

You can easily notice an engine running on three cylinders and it didn't take me long to check # 1 and change that spark plug first.

Actually, an old race track driver from Maine gave me that block off plate and then gave me a hot air inlet pipe and told me I would never need it!

He was right!

This is where you live makes a big difference. It never occured to me living in Arizona that 110F air rising off 150F pavement then being pulled
threw a radiator with 200F water in it & blasted on the front of the engine block would make # 1 cylinder run too cool to achieve good
combustion. Isn't the intake manifold design & the odd firing order also a contributer to air/fuel mixture imbalance in the cylinders at
lower speeds? Has leaning the mixture been tried to prevent the sutting of # 1 cyl.?
Craig.

I don't think this is your problem, but I will mention it. A slight leak in the intake at port for 3 and 4. The fuel mixture is increased slightly to smooth it out causing the first two cylinders to run rich. I will repeat I don't think this is causing your problem, but something you could check.
A probable cause. The air through the fan hits front of intake manifold and front of head and block causing it to run cooler. The heat from all the exhaust ports accumulates at the rear of the exhaust manifold causing some heat transfer to the rear of the engine.
This is a Model T and if it runs smoothly, nothing to be concerned with unless it misfires.
Norm

With an updraft carb centrally located the number 1 and 4 would tend to be lean. This is even more exaggerated on a 6 cylinder engine. What you have is soot from a cold cylinder. Common on many Ts unless you run a 160 degree thermostat. I know guys will say Henry didn't use them, but he cut every expense on building these cars. I run one and my engine is constant temp front to rear. All 4 spark plugs stay clean. Use a hand held IR temp gauge and you will see the front of the engine is considerably cooler than the back. https://www.harborfreight.com/121-infra ... 63985.html

If the car runs fine and the color of the #1 plug is a concern, maybe you could find a plug for #1 that is one or two steps hotter than the other three.

I used to have a Nissan pickup with dual plugs per cylinder. Nissan specified a different heat range for the two plug positions.