13T - Fouled plugs

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Darin Hull
Posts: 241
Joined: Fri Apr 17, 2020 2:15 pm
First Name: Darin
Last Name: Hull
* REQUIRED* Type and Year of Model Ts owned: 1913 Model T
Location: Cartersville, GA
MTFCA Number: 29699
MTFCI Number: 25147
Board Member Since: 2010
Contact:

13T - Fouled plugs

Post by Darin Hull » Sat Nov 28, 2020 3:11 pm

I had a fan pulley go bad. Took off the radiator, replaced the fan pulley, and knocked out a few other little projects/maintenance. I was redoing the timing so I took off the #1 spark plug... I was surprised to see it appeared fouled. Took off the #2 plus since I’ve heard the front spark plug can be the most fouled. #2 seemed fouled, also.

So, mixture. I’ve set my Holley carb per the instructions on the MTFCA encyclopedia site:

http://www.mtfca.com/encyclo/holley.pdf

I have to run rich to get the car to initially start and then can dial it down quickly. 13T runs about one and a half turns open. Car runs smooth... seems to have the power I need.

Reading previous forums on fouled plugs I ran across this one:

http://www.mtfca.com/discus/messages/29 ... 1191186168

It mentions motorcraft plugs and gap as potential issues. I have motorcraft plugs gapped at .030.

I’ll attach a pic of two of my plugs... would you consider this fouled? Or would this be acceptable?

Darin
Attachments
1EAA9749-A8B4-465F-81A1-D0C0A729DB84.jpeg
EA1C066D-DF38-4E38-B64F-0033CFF648DD.jpeg
EA300B9C-6F2A-453C-A374-B1C17361B54C.jpeg
Last edited by Darin Hull on Sat Nov 28, 2020 5:31 pm, edited 3 times in total.


Jerry VanOoteghem
Posts: 2952
Joined: Sun Jan 06, 2019 4:06 pm
First Name: Jerry
Last Name: Van
Location: S.E. Michigan
MTFCA Number: 24868

Re: 13T - Fouled plugs

Post by Jerry VanOoteghem » Sat Nov 28, 2020 3:57 pm

If the car runs well and does everything you ask of it, then I would not consider that plug to be fouled. :)

You could try leaning it out a bit more perhaps. I usually lean it out till I notice the power going down a bit, with slower acceleration, then I richen it up from there till performance comes back.


Norman Kling
Posts: 4072
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: 13T - Fouled plugs

Post by Norman Kling » Sat Nov 28, 2020 4:04 pm

Your plug looks about right for one which has been used. The contacts are clean . If it were fouled it would be all carboned up including the gap. Does the engine run smoothly?
There are two things which can foul a plug. One is an excessively rich fuel mixture which produces black carbon. If the spark jumps down through the carbon to the ground instead of across the points at the top it would be fouled. The other reason for fouling is excessive oil leaking through the rings. That leaves a black oily carbon around the end of the plug. Even the inside of the cylinder head and top of the piston will have carbon on it after the engine has been run for a while. If you have access to a spark plug cleaner, you can clean the plugs and they will run fine.
Norm


Topic author
Darin Hull
Posts: 241
Joined: Fri Apr 17, 2020 2:15 pm
First Name: Darin
Last Name: Hull
* REQUIRED* Type and Year of Model Ts owned: 1913 Model T
Location: Cartersville, GA
MTFCA Number: 29699
MTFCI Number: 25147
Board Member Since: 2010
Contact:

Re: 13T - Fouled plugs

Post by Darin Hull » Sat Nov 28, 2020 5:14 pm

I took out each plug and noticed the common result of the plugs looking progressively better the farther back ya go. I cleaned the plugs with a soft brush I usually use to clean carbon off my firearms. I found almost all the material appeared to be like a soot. Came off very easily with brushing. There were some small areas of a harder deposit which I was able to mostly get rid of with a fingernail. Rechecked gaps and put them all back in.

Jerry - Thank you for the “sniff test” way of looking a the issue. The 13T has been running just fine, acceleration and idling all seem well.

Norman - Yes, it seems to run smooth. Once again, I have nothing to compare it to because I’ve only been around this T... but I’d guess it runs just fine.

Thank you,
Darin

User avatar

TWrenn
Posts: 3389
Joined: Sun Jan 06, 2019 10:53 am
First Name: Tim
Last Name: Wrenn
* REQUIRED* Type and Year of Model Ts owned: '13 Touring, '26 "Overlap" Fordor
Location: Ohio
MTFCA Number: 30701
MTFCI Number: 24033
Board Member Since: 2019

Re: 13T - Fouled plugs

Post by TWrenn » Sat Nov 28, 2020 7:48 pm

I agree it really doesn't look all that bad, the important parts seem clean. Here's my #1 plug off my '13 when I too was doing some routine maintenance two weeks ago.
Attachments
20201111_105206.jpg

User avatar

Bill Robinson
Posts: 302
Joined: Sun Jan 06, 2019 2:24 pm
First Name: Bill
Last Name: Robinson
* REQUIRED* Type and Year of Model Ts owned: '21 Depot Hack, '25 Touring Car, '26 Roadster Pickup, '27 Tudor, & another '27 Tudor
Location: Salty Bottom, ALABAMA AL
MTFCA Number: 22487
MTFCI Number: 17887
Board Member Since: 1999
Contact:

Re: 13T - Fouled plugs

Post by Bill Robinson » Sat Nov 28, 2020 8:13 pm

Myself, I wouldn't call those plugs "fouled". "Sooted", maybe, but not "fouled". #'s 1 & 2 tend to collect soot more than 3 & 4 because they are at the front of the engine and tend to get the coolest water coming from the radiator, therefore don't burn the fuel as efficiently. I think what you are seeing is perfectly normal unless the sooting occurred in an hour or less.


Norman Kling
Posts: 4072
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: 13T - Fouled plugs

Post by Norman Kling » Sat Nov 28, 2020 8:52 pm

One other thing which could cause the plugs to soot up, would be engine running too cold. If you live in cold climate you might need to put something to cover part of the radiator when it is very cold. Another thing which could cause a T to run cold would be a water pump especially without a thermostat. And with the water pump the water would take the shortest route from the pump through the radiator and back to the pump. That route would be through the front of the engine. An interesting thing happened with my first Model T. When I bought it there was a water pump on it and one day we took a tour, in I Think, February. We went into the mountains where it is colder than down here in the foothills. We stopped for a break. I noticed many of the drivers standing in front of their radiators to keep warm. Mine was still cold!
Norm


Art Wilson
Posts: 32
Joined: Sun Jan 06, 2019 8:53 pm
First Name: Art
Last Name: Wilson
* REQUIRED* Type and Year of Model Ts owned: 1911 Touring
Location: San Diego

Re: 13T - Fouled plugs

Post by Art Wilson » Sat Nov 28, 2020 11:03 pm

The real reason stock Model T's run rich on the front two cylinders.

The problem is due to the design of the carburetor and the shape of the intake manifold.

The carburetor supplies fuel at the bottom of the venturi in the form of a puddle.

The bottom side of the intake manifold is gently curved from the carburetor up to the front intake port. The top side basically follows the same curvature up to where it curves back to the rear intake port.

This gas puddle from the carburetor is sucked into the bottom area of the intake manifold, and while getting partially atomized, flows up to the front intake port. The leaner part of the mixture goes to the rear intake port.

I discovered this over 40 years ago when I smoothed the inside of an aluminum intake manifold in an attempt to get more horsepower. I could not get the engine to idle on all four cylinders. By varying the mixture I could get it to run on the front two or the rear two cylinders, but not both the front and the rear at the same time.

I put the stock iron manifold back on the car and it runs fine. The front two cylinders still run a bit rich as do most Model T's with stock intake systems.


Moxie26
Posts: 1315
Joined: Sun Jan 06, 2019 8:20 pm
First Name: Robert
Last Name: Jablonski
* REQUIRED* Type and Year of Model Ts owned: 1926 Runabout
Location: New Jersey
MTFCA Number: 407
MTFCA Life Member: YES
Board Member Since: 1999

Re: 13T - Fouled plugs

Post by Moxie26 » Sun Nov 29, 2020 2:16 pm

Darren; it's your choice either get new plugs or clean the ones you have, and set the gap to 0.025" . Also be a little more attentive on your running fuel mixture after the engine warms up.


Topic author
Darin Hull
Posts: 241
Joined: Fri Apr 17, 2020 2:15 pm
First Name: Darin
Last Name: Hull
* REQUIRED* Type and Year of Model Ts owned: 1913 Model T
Location: Cartersville, GA
MTFCA Number: 29699
MTFCI Number: 25147
Board Member Since: 2010
Contact:

Re: 13T - Fouled plugs

Post by Darin Hull » Mon Nov 30, 2020 5:23 am

Robert,

Why do you suggest .025? Is that for motorcraft plugs or T plugs in general?

Darin


ThreePedalTapDancer
Posts: 1419
Joined: Sun Nov 24, 2019 2:29 pm
First Name: Ed
Last Name: Martin
* REQUIRED* Type and Year of Model Ts owned: 1914 Touring, 1909 Touring
Location: Idaho

Re: 13T - Fouled plugs

Post by ThreePedalTapDancer » Mon Nov 30, 2020 7:12 am

I suppose fouling was a common problem, hence the development of all kinds of accessory gizmos that aid atomization of the fuel. Most of these gadgets look like a steel gasket with a fine mesh of swirling design cut in the center.

http://www.mtfca.com/discus/messages/17 ... 1301424727
8CE6DDF8-A4E9-4CB4-9FE5-17464F3A0C2B.jpeg
D859257F-7FAC-4B33-A5E5-506B29F25906.jpeg
C00FAE1B-1527-4499-8550-2F9A475AE953.jpeg


Moxie26
Posts: 1315
Joined: Sun Jan 06, 2019 8:20 pm
First Name: Robert
Last Name: Jablonski
* REQUIRED* Type and Year of Model Ts owned: 1926 Runabout
Location: New Jersey
MTFCA Number: 407
MTFCA Life Member: YES
Board Member Since: 1999

Re: 13T - Fouled plugs

Post by Moxie26 » Sun Dec 06, 2020 3:02 pm

Darin : Gaping plugs at .025" puts less strain on the coils and engine will start and run better IMHO . Works for me on our '26's 6 volt battery/ignition supplied system. . Even years ago on our 1950 Buick, they specified a gap of .025" on the AC-46 plugs.... on a 6 volt system..... no problems there also.

Post Reply Previous topicNext topic