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Old 06-10-2021, 10:55 PM   #1
ETAModel
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Default Longest trip yet...MPG suck!

Got the 30 Fordor going, took it to gas station first thing and filled her up with premium 100% gasoline. Then turned on speedbot and went for a LONG (for me) drive. My longest yet, 48 miles. Mostly county roads, some city but not much.

At the end of drive took her back to gas station and topped her off, to see how she did. She used 4.4 gallons, so roughly 10.5 MPG without using my calculator.

In my opinion...THAT SUCKS!

I had the throttle turned about 2/3 of a turn out. Seems I read somewhere that when your on the highway you can almost close the throttle jet and it will still run fine.

To prove it to myself I hit the local US Hwy and closed the fuel off, then cracked it open. She didn't hesitate or stall or nothing, ran like it had all day. BUT, when I got back in town and hit some stop signs she DEFINATELY needed more fuel going in, as she sputtered and almost stalled. I turned her back to 2/3 open and it ran fine in town.

The plugs look ancient, I need to pull them and at least clean them, and order some replacements.

Remember Guys, I have about a dozen drives under my belt, probably 200-250 miles total thus far, today excluded. So I am still a Newbie to the Great Model A.

Should I leave the throttle at 2/3 turn while she warm up and in town, and then close it down on the road?? I'm not worried about the Cost, I'm concerned about running out of gas! The Gas Gauge doesn't work, its on the list of repairs. But still, this is TEXAS, there's times you can drive a hour or more (in a modern car) any direction without seeing a gas station.

Thanks for your help thus far.
ET
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Old 06-10-2021, 11:45 PM   #2
TerryH
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Default Re: Longest trip yet...MPG suck!

The Fordor is a heavy Model A, and with mine, driving in town all the time, with lots of stop and go driving, I only get about 15-16 mpg. On the open road, and cruising 55 mph, with overdrive, I get 20-22 mpg. 10 mpg sounds quite low, even around town. Once warmed up, you should not have to adjust the GAV (not throttle). All Models are a little different, but many seem to like 1/4 turn open after warming up. I would do all the basics first: Check your points and gap, check the timing, pull spark plugs, maybe replace, clean and gap those. Another place to check would be your carburetor….make sure your jets are properly size. And at speed, your spark advance should be at least 3/4 down.
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Old 06-10-2021, 11:53 PM   #3
ETAModel
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Default Re: Longest trip yet...MPG suck!

Thanks for the reply...I'll bite, what does GAV stand for? My old First Shirt told us if you don't know what an acronym means, then it doesn't apply to you. I think in this case he was wrong.
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Old 06-11-2021, 03:04 AM   #4
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Default Re: Longest trip yet...MPG suck!

Tuned B engine in my '30 Fordor running 18's and 3.54 gears and I get low 20's out of mine. And I don't hang around...

Couldn't afford to go anywhere at 10mpg!
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Old 06-11-2021, 05:25 AM   #5
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Default Re: Longest trip yet...MPG suck!

I agree- 10 mpg does suck, but It sounds like it will be tough to get much more then 15 mpg out of your car.
so many variables and the biggest being the weight , as mentioned and the other question is, what condition is your engine in?


is it tired?
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Old 06-11-2021, 07:10 AM   #6
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Default Re: Longest trip yet...MPG suck!

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Quote:
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thanks for the reply...i'll bite, what does gav stand for?
gas adjustment valve=gav:d
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Old 06-11-2021, 07:11 AM   #7
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Default Re: Longest trip yet...MPG suck!

GAV is the Gas Adjusting Valve, the knob under the fuel tank in front of the passenger. It adjusts the carburetor.
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Old 06-11-2021, 07:15 AM   #8
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Default Re: Longest trip yet...MPG suck!

GAV: Gas Adjustment Valve.

Several things effect gas millage. The GAV should be turned in while cruising down the highway. The spark should be adjusted correctly and when cruising down the highway advanced a little. Make sure the points are adjusted correctly and the car is timed correctly. Also, just like in a modern car, how you drive can effect mileage. Keep the tires inflated to 35 psi. Overdrive helps and the gear ratio of the rearend will effect mileage. Years ago I changed out 4.11 gearing for 3.7 gearing to improve my coupe top end and mileage.
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Old 06-11-2021, 08:42 AM   #9
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Default Re: Longest trip yet...MPG suck!

Something that will probably help with you gas mileage is to stop using premium high octane fuel.
High octane fuel is designed to be harder to ignite. This is to reduce the tenancy for fuel to prematurely ignite in high compression engines. Model A's even with the higher compression heads are still a low compression engine. Put the lowest octane fuel you can into your car. It will give you more power and most likely better mileage.

In regards to the GAV as I understand it, it is not a good idea to close it all the way as it can cause the engine to run too lean and possibly cause engine damage.
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Old 06-11-2021, 09:44 AM   #10
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Default Re: Longest trip yet...MPG suck!

Possible dragging brake shoes on one or more wheels? See if all 4 turn freely when off the ground.
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Old 06-11-2021, 10:17 AM   #11
Marshall V. Daut
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Default Re: Longest trip yet...MPG suck!

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Old 06-11-2021, 10:22 AM   #12
Jeff/Illinois
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Default Re: Longest trip yet...MPG suck!

Wow 10MPG IS pretty bad on a Model A Ford.

Our '29 Tudor got 20 MPG all day long on at that time Sunoco regular 190. (1970's)

I realize a Fordor is a heavy car but you can get better than that.

Good luck, you will find the problem just take it one step at a time . The guys have some good tips on here for you.

Let us know how you come out.
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Old 06-11-2021, 10:26 AM   #13
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Default Re: Longest trip yet...MPG suck!

As a new owner of a Model A you should get a copy of the original owner’s manual. It explains everything you need to know for proper setup and driving. They’re available from all A suppliers.
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Old 06-11-2021, 10:49 AM   #14
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Default Re: Longest trip yet...MPG suck!

I have a 45B Deluxe Coupe and a 190A Victoria Coupe. Both have Model "B" engines with Model "A" Zenith carburetors, and no overdrive. Both have stock 3.78:1 differentials. The 45B has a 4.6:1 Compression Model "B" head, and the 190A has a 5.5:1 Model "A" type head.
The 45B Coupe gets 15 mpg and the 190A gets 18 mpg. I run both cars with the lowest cost 87 Octane with Ethanol gasoline I can find in Gulag New York.
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Old 06-11-2021, 11:17 AM   #15
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Default Re: Longest trip yet...MPG suck!

I tend to get mid to high teens in my Fordor with 3.78 gears and I live in hilly terrain and have a lead foot. Sounds like the carb is in need of some attention, GAV needing to be 2/3 of a turn out is suspect. Dragging brakes are a good suggestion too.
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Old 06-11-2021, 11:23 AM   #16
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Default Re: Longest trip yet...MPG suck!

As a newbie to the A I got worse fuel economy than I do now, mostly due to shifting habits and maybe not controlling the timing well enough. I noticed a big change when I retimed the engine as well.
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Old 06-11-2021, 11:35 AM   #17
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Default Re: Longest trip yet...MPG suck!

The GAV is the trim adjustment control for the high speed jet circuit in the carburetor. Adjust during cruise for best overall running down the road. The only other adjustments to it would be for higher or lower altitudes or temperatures. The idle circuit takes care of idling and it should be adjusted for best running at idle or best manifold vacuum if you have a MAP gauge.

Timing is very important. You want the spark to be able to reach the full measure of advancement as recommended by Ford Motor Co's publications but an operator of one of these cars has to know when to retard the spark not only for starting but also for pulling a load up a hill. Nothing is automatic on these old cars so it all has to be done by the operator to get best mileage.

The type of terrain can also make a difference. A car will get the best mileage in relatively flat land situations and at relatively slow speeds compared to modern highway speeds. How the milage is measured can also have an effect. The old speedometers need to be accurate or a GPS should be used unless it is a closed course of know distance values.
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Old 06-11-2021, 12:00 PM   #18
nkaminar
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Default Re: Longest trip yet...MPG suck!

One thing I forgot to mention is that you will get better mileage with a higher compression head. But first check all things that others have suggested.
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A is for apple, green as the sky.
Step on the gas, for tomorrow I die.
Forget the brakes, they really don't work.
The clutch always sticks, and starts with a jerk.
My car grows red hair, and flies through the air.
Driving's a blast, a blast from the past.
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Old 06-11-2021, 12:22 PM   #19
1931 flamingo
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Default Re: Longest trip yet...MPG suck!

When I had my A I never was concerned with gas mileage. Having too much fun. ,When it got to a 1/4 tank I just put more in. My 40 coupe now with dual 97's and hi-comp heads is a gas guzzler (like my 300 C with the HEMI. Still having too much fun.


Paul in CT
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Old 06-11-2021, 01:31 PM   #20
ETAModel
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Default Re: Longest trip yet...MPG suck!

Quote:
Originally Posted by Bud View Post
GAV is the Gas Adjusting Valve, the knob under the fuel tank in front of the passenger. It adjusts the carburetor.

I know what is it, and where its located, I just didnt know what GAV stood for..I was calling it the throttle...still learning the nomenclature
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