My T isn't ready for the road yet but I hope to get it finished mid summer. I don't know if this is a problem but the # 1 plug is burning richer than 2,3,and 4 which is a powder brown . anyone else have the same results ? I have only run this engine in my garage. it has been up to temperature and seems to be very smooth . it will start on battery or mag , the compression is 47 Lbs. hot and I should kick myself but I drilled a hole in the underside of the intake for a vacuum gauge. the gauge shows the engine to be in good working order. I switched the coils and plugs around and the front plug always gets charcoal colored . thanks, Ken
I don't know of any reason why one cylinder should run richer than another. But, it is quite often that #1 will run colder than the others because the coolant takes a shortcut from the intake on the side of the block to the front of the engine outlet to the radiator. Unless you continually foul the spark plug, it is not a problem.
Ken -- The #1 cylinder runs cooler than the others because of the coolant flow, as Norm said, and also because the fan blows right on it. What type of spark plugs are you using? If you are using modern plugs, you might consider using a hotter heat range plug in that cylinder.
Thanks Norman and Mike.
I have modern champion X plugs now. are there hotter X plugs available ?
make the spark plug gap smaller on that cylinder it should make it run hotter
I'll give it a try, my plug gap now is 0.28 thanks, Ken
I believe the reason the number 1 and 2 cylinders run richer is due to the way the stock intake manifold and carburetor are designed.
With that design the fuel enters into the carburetor air inlet passage at the bottom of the carburetor venturi as air is drawn through it. Most of the fuel is mixed with the air to form the fuel-air mixture as it is drawn through the intake manifold. However some of the unmixed fuel is drawn along the bottom of the carburetor passage and up the forward side of the intake into the front two cylinders. This makes the fuel air mixture richer for the front two cylinders.
I became knowledgeable about this when I polished the intake passage of an aluminum intake manifold to get more power. By adjusting the carburetor the engine would idle on either the front two or the rear two cylinders, but no way could I get it to idle on all four. I then installed a stock cast iron manifold with a rough air passage, which helped produce a more thorough fuel-air mixture and the car ran fine on all four.
I concluded that the polished aluminum passage allowed much more of the unmixed fuel to be drawn along the front edge of the manifold and into the front cylinders.
Art, since it was a high volume alu manifold you had a problem running at idle, I'd suggest it was a leak in one of the two intake ports. Often the oversize intakes are too much oversize on the outside so they need to be ground off a little to seat properly. See this earlier thread:
Ken: I agree with the others about the tendency of the coolant to take a shortcut, making #1 run cooler. One thing that is easy to try is to pull the fan belt and try running without the fan when yu're driving the car, not just standing still. If you're not doing parades, it's likely to work just fine. Should there be a overheating problem, then it's easy (ok, be careful so you don't get a burn) to put the belt back on
Ken ; The book ; " The model T Ford Owner of Murray Fahnestock " on page 303 to 305 tell you the whole story about your problem with #1 .
Head Gasket??? Dan
Well, I'll have to check my book because I'm having the same problem. I was about to swap out the coil but I'll see what Mr. Fahnestock has to say!!
At the risk of opening a can of worms, I think the 28 thou gap is too small. I'd suggest 35.
It was a stock aluminum intake.
Can you get an accessory up draft intake and carb to try on your engine. It would be interesting to see if it makes a difference.
I just don't see how a cylinder that is getting the same fuel air mixture as the others can change that fuel air mixture to be richer just because it is not quite as warm. To make it richer either air (oxygen) needs to be taken out or additional fuel added. Cooling the whole mixture would slightly reduce the volume of the mixture but the amount of fuel and oxygen in the mixture would remain the same.