How Do These Spark Plugs Look?

[BLB27]

Today, my son and I drove my 1927 coupe 20 miles and used 1.75 gallons (11.3 mpg). It was 40 F. There were no steep hills. I have 150 miles on the coupe.


How do the sparks plugs look and what do you think of the mpg?

[jiminbartow]

They look great…and normal. Mileage is fine. Your engine is not broken in yet. As it loosens up, it will get even better.

Keep a journal of how many miles you drive and how many gallons are used. Calculate the miles per gallon based on an average speed of 30 to 35 mph. The more you drive, the more you will see your mileage improve as the engine loosens up. You should invest in a Stewart Warner 490A speedometer (for 1926-‘27 passenger T’s) to determine miles per hour and miles driven. I have one in my 1926 coupe. Any other kind of speedometer will be too big to fit the dash with the cowl tank behind it. If you don’t want to do that, on each drive, get a friend to follow you and keep track of those things for you. It is also a good idea to have a chase vehicle to protect your rear from modern speeding cars coming from the rear, with flashing lights. Also, in case you run into mechanical problems. Jim Patrick

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[Michael Peternell]

Nothing wrong there.

[TXGOAT2]

The plugs look great. it certainly isn't running rich. Mileage is poor. A new engine will loosen up with use. I'd look for any evidence of dragging brakes, miss-aligned wheels, etc. When sitting on level, hard ground, the car should be easy to push when the lever is straight up. Tire pressure is important. Balloon tires need around 28 to 30 PSI on a coupe. Clincher tires need 55-60 PSI. The engine needs to run at around 180F to 200 F. Proper use of the spark lever is necessary for good mileage and power. In winter, I'd run a 5W20 synthetic oil in that car.

[TWrenn]

We can only make the assumption that the 150 miles on it is on a "fresh engine"...which he doesn't say. Maybe he just GOT the coupe and put the 150 miles on it? I'd like to know what a '27 coupe weighs, is it all steel? Lord knows I was shocked at the weight of my '26 Fordor "Stanley" when I had him weighed, he came in at a respectable 2240 lbs. He gets 18 mpg. on a good day and that'll be all the better he does. 99% flat land. Only real hills he encounters is an overpass, occasionally a "real hill" but at that only once or twice of a tour. As others say, check for "things dragging".

[Norman Kling]

I have not measured the gas mileage on any of my T's. They are all open cars. I know that if I fill up the tank in the morning, I can drive all day on one tank of gas unless I am in the mountains, and then I need to keep it above half tank so it doesn't starve going uphill. I rarely check the spark plugs. I can also tell the difference in hill climbing with more passengers. I have a hill I can climb in high, easily by myself but with 4 in the car, I need to use Ruckstell.
Norm

[TRDxB2]

These plugs like perfect. But its best to keep a record of previous events..
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1st its a new rebuilt engine
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Post by BLB27 » Mon Dec 11, 2023 9:00 pm
My 12-04-23 post is getting long so I am starting a new post to provide an update.
I recently drove the coupe 20 more miles. I don't have a speedometer so I verified the miles by driving my F150 the distance. As mentioned in the original post,. I had previously checked the mpg after a 12 mile run and found it was 7mpg.
After that check, I removed the spark plugs and found what is shown in the attached photos. Surprised to see the difference between plugs 1,2 and 3,4.

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On the 20 mile run, I adjusted the carburetor to a leaner setting by turning it down until the engine started to hesitate and then backed it of a little. I carefully checked the gas used using Lang's dip stick and found I had used just over 1 gallon so that's about 18mpg. Before making the 20 mile run, I cleaned the plugs and after the run they were still clean and all the same condition.
I plan on making another 20 mile check. I now have about 60 miles on the coupe.
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So on this latest run you reported "Today, my son and I drove my 1927 coupe 20 miles and used 1.75 gallons (11.3 mpg). It was 40 F. There were no steep hills. I have 150 miles on the coupe.your plugs look great but your down to 11.7 mpg.
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In looking at Lang's Dip stick the Cowl graduations are not evenly spaced so it would be a source of error in your calculations.
It all depends on how you determined gallons used.