Both my T and Curt Carrick's foul plugs regularly. We both have a Z head, and new Berg's radiators. THe engines are never really getting hot, we are figuring they are fouling the plugs because then run too cold. WHat is recommended, and how / where is it installed? under the outlet?
I'm not so sure a thermostat will correct the problem. Before you add one why not play around with the fuel mixture a little. Sounds to me like you may be running a little rich.
You may benefit from a thermostat. I speak to that in a bit, but first a few other points.
What plugs are you using? If your Z head is tapped for 14MM plugs a hotter plug may help.
Simply removing the fan belt may help.
When I replaced the radiator on my coupe (stock head)I used a flat tube rad from Brassworks. The engine then always ran cool and just wasn't happy. I wondered if I would have been better off with a round tube rad as I feel that the flat tube may cool TOO well. Anyway, I did install a thermostat (bought from Lang's) and that brought an improvement. Now the motometer will indicate at the bottom of the Normal Operating circle.
Good luck with your project. Bill
Both of our cars have flat tube radiators, neither one is running a fan, and we have adjusted carburetors frequently. Kind of run out of options. This morning, and it is only 60 today, I ran the car to a local coffee cruse car show. Far enough it should come up to operating temperature. the Monometer registered maybe an eighth of an inch and no more both ways. The car was not real interested in starting cold, I;m sure when I pull the plugs they will be black. A hotter plug is an easy option, as I do have 14mm plugs.
I agree on the hotter plug IF everything else is operating as it should be. Meaning in this case the timing and carb are properly adjusted and operating without issues. So I also assume that turning the mixture screw in and leaning the carb makes it run worse.
So if everything is in the sweet spot, step up a heat range in the plugs and see if it clears up a little. If you still need more, try the next range up, but only do one at a time.
Also depending on the plug, you can mess around with projected and non projected tip plugs if there are no clearance issues with the pistons.
If the car is running under 160 deg. then it's running too cool. That can lead to the carbon and lots of waste products getting into the oil. I would start with the 160 thermostat which by the catalog is used for engines without a water pump, see if that helps. Then try a different set of plugs. The nice thing about a thermostat is it's self regulating, a piece of card board would work but you would have to stop and get out to adjust it when the engine gets warm or running too cold.
I'm with Henry on this as the fuel mixture adjustment is there for a reason!! Bud in Wheeler,Mi.
The plugs are proably not extending far enough into the combustion chamber. Auto lite 3924 plugs have a long reach and are hot enough to not foul. A thermostat would not affect the problem, and you do not need one. Your temp gauge does little of. value on a thermo siphon cooling system.
Thank you for the responses, and I can appreciate all of the opinions expressed. I put hotter plugs in the car, and a 160 thermostat. I just got back from a test drive, probably a good 12 miles or so. Far enough it should come up to a good operating temperature. In the past the Monometer registered maybe an quarter of an inch and no more.
HOLY GUACAMOLE what a difference in how the car ran. More power, and more response in high gear. The Monometer never hit the range it was in in before. Once fully warmed up it stayed at normal, just below the circle, and as the thermostat cycled it would bump up into the circle a little bit, and than drop down just below normal
This time I think the thermostat was the answer
Well I am pleased to read that you have brought improved performance to your car. They call it Normal Operating Temperature for a reason. The Model T needs to run hot, probably around 185-190 degrees. I realize that such a temperature is not that much below boiling, but if run too cool the engine is just not happy.
What works well for your car may not be best for mine or for the other guy's car. Sure, there are some general guide lines that apply to all Model Ts, but sometimes things like plug heat range, plug gap, carb mixture, and other details need to be tailored to an individual engine. "Different strokes for different folks" Your milage may vary.
Good luck with your project. Bill
Amen to that Bill. My engine is a clone to Curt's engine. I mentioned Curt in my original post. on this thread Both are 26/27 style blocks, and are fresh rebuilds. The serial # on Curt's says his is a '31 engine, obviously a replacement along the way. Mine has no serial number. Both have aluminum pistons, high lift cams, Z heads, Texas T distributors, and no magneto's (we both had issues with our magneto's). Both have new Berg radiators. Curt finished his engine a year before I finished mine. Curt's engine fired on it's own before the battery gave out the first time. Mine had to be pulled by a truck to start, and would not start by itself for long time. It never pulled in high gear like Curt's did, especially after first start up, and is just beginning to catch up. Just running the engine at proper temperature slingshoted my car ahead. We will see what happens when he adds a thermostat.
Back home in PA drivers used to put cardboard or heavy paper in front of the radiator in the winter to hasten warmup and get a little more heat from the heater. If there was not enough antifreeze present the radiator would actually freeze up at highway speeds. Too much airflow! Why don't you guys try blocking off some of the radiator with a black sheet of something or other to see what improvement you get?
Mahlon read my posting.
Doug, what plugs did you have in the engine? And what did you replace them with?
The before plugs were NGK GR4's. The replacements are NGK B9ES's. I got them at O'Reilly's Auto Parts, only because they are the closest parts store to me. The original plugs were a cross reference to what was recommended to be used with this head. Keep in mind I have a Z head with 14mm plugs. The replacements he gave me are supposed to be the next hotter heat range.
Can someone explain to me what makes one plug "hotter" than another?
I am amazed at the difference in performance in this car. I really don't know how a Model T is supposed to behave. I have only driven maybe 5 different T's. My car is my first T, the first engine I had in the car was supposed to be a good engine, It was okay, if you don't mind a rod knock, and 30# compression, and no ability at all to handle a hill. If you don't know Omaha, it is a hilly city.
I have a fresh rebuild 26/27 block (no serial #) with a Z-head, aluminum pistons, Chaffin Traveler's cam, Texas T distributor. Before a thermostat, and hotter plugs, performance was mediocre, with a hesitation, and stumble moving to high gear. With the hotter plugs, and the thermostat, the car has really transformed. Today was a rainy drizzly day, not a day for a car with no top. I did finally have a dry spot to get the car out, and again like yesterday I am amazed at the difference. Probably drove another 10 miles tonight, and it pulls hills great, and no miss or hesitation going into high gear, easy to get the car up to upper 30's MPH, even on the hills. I am really starting to like this car, finally
And I caught my earlier error, it is a Motometer, not a Monometer. Grey hair you know
Your high temps were only in the low-mid 60's last week. My low temperature cutoff for driving is 55 degrees!
I don't have any experience with the Model T hotrod engines, but why they would run any "cooler" than a stock Ford?
Here is an earlier post on temps in March:
Ken in Texas
I use the hottest Bosch platinum plug I can find in my Z heads. Have never fouled a plug. They last for years. I had the same set in my Fordor for 12 years. I only replaced them because after all that time it just seemed like I should, but it still was running good. And yes, it too runs very cool.
How does your car run when it's 95 degrees and 95% humidity outside in Omaha?
When I lived in Omaha I'd run a coolant restrictor in one of my muscle cars without a thermostat to keep it at temp. It'd run too hot with a thermostat.
I'll try to answer your question. A hotter plug has internally a longer path for the heat to get from the center electrode to the metal body that screws into the head. The longer the path for the heat, the hotter it will be at the point where the heat is introduced. In the end the heat goes to water.
I will concede the carb was rich when the car finally has gotten up to an operating temperature. I have leaned it back quite a bit. It is now at the base setting + 1/8 more. I have not since had time to pull a plug to see how it is doing. It is not running as it did as they fouled. It really has made a difference letting the engine get hotter. The stumble and miss going into high gear is gone now. I will have to put the fan back on the car. Everything is fine until I get caught at the start of a longer stop light, it starts to push the upper limit of the heat range. All is well again when the car gets moving again.
I have never had the car running in the extreme hot part of summer. I have only driven the car in fall and spring so far. Most of last summer was lost to replacing the engine. If the thermostat proves too much then it is east to remove.