Gas Mileage?

SUHRsc

SUHRsc

Well-known member
Have any of you checked what kind of gas mileage you're getting in your model-A's?

I have gradually been collecting pieces to build a 1930/31 pick-up. Just a pile of parts more or less to build a driver. Nothing fits to a certain build date.
An oppertunity has popped up for me to buy a chassis, so I'm considering moving forward with the project. In order to be able to tie money into it right now.. it needs to be able to replace my "modern" daily driver which is on its last leg. The problem is that I'm currently getting about 24 miles to the gallon.

My truck would likely have a counterbalanced model-B motor (just because its what I have sitting here) but all else stock model-A. I believe the chassis has a 3.78 ratio rear end.

This would be my first go at a somewhat stock model-A if I can make ends meet to get it rolling.

Does anyone have any thoughts, ideas, etc. Things that you have done to improve gas mileage, aside from overdrive or gear ratio changes.
Would a 6:1 cast iron head make an improvement? How about a different carburetor? Ignition? etc...

Thanks alot!
Zach
 
Its not likely that you will get 24 miles per gallon unless you drive 30 mph or less . You will get better gas milage with a higher compression head plus it will run cooler. a performance coil such as the Pertronix flame thrower coil will help and so will Champion W18 spark plugs. A free flowing exhaust such as Aries or a gutted straight through muffler will give a noticable improvement. My 31 roadster is getting about 20 mpg with all of the above plus two model B carbs on a cast iron Trojan intake and 3.78 gears. My stock 31 tudor with a side bowl Zenith 2 only gets around 17. I have found that the model A will get better gas milage with dual updraft carbs than it will with a single original Zenith. I guess it distributes the mix more evenly to the cylinders than the original setup. This seems to be the case with two of our model As. Others that I have talked to that are running dual updrafts have noticed improved gas milage.
 
I'm about as far from being an authentic restoration guy as they come, but I would urge you to reconsider your vision. The Model A, although a really swell piece of machinery, is just an inherently inefficient design by modern standards. If the mileage really matters that much to you, I fear you are wanting it to be something that it just ain't, and are about to start down an expensive, disappointing trail-of-tears. This advice from a guy with a Brumfield 5.9 head, counterbalanced crank, oversize valves, F-150 OD trans, Aries muffler, 12 Volts Pertronix ignition, and hydraulic brakes, and who for reasons none of us can figure out gets better mileage than anyone else in our club who has traveled with him.

Steve
 
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"Would a 6:1 cast iron head make an improvement?"

I can't speak for other brands but the Brumfield Heads will definitely help the gas mileage. Even people running heavy fordors loaded with people have reported significant improvement.

This is because the Brumfields Heads generate considerable turbulence by design in addition to the increase in compression. The result is a more uniform mixture that allows the fuel charge to be consumed to a greater extent with less waste than with the stock head and also some other brands of high comp heads as well.

Moreover, the increase in power allows a reduction in the amount of throttle necessary to maintain the same speed and load. (Notice I said "same speed and load." Wide open throttle conditions or generally fast driving are a different story.)

Also, depending on the level of ethanol (pump claims 10% or less in TX.) the gas mileage will be lower than in the past.


Larry B.
 
Any differents in mileage between 100% gas and the stuff with ethanol? I just got my 30 coupe last month and been running premium with ethanol...havn't tried the 100% yet.
 
they just were not built for mileage . when mine was stock it was in the 18-20 mpg range . since i put dual 97's it has gone to a big 10 !! good luck zach .. steve

i would ride your bobber !!!!!!!!!!!!
 
Last summer on a club trip we got 21.5 with a Tudor on the road. The only modification was it was bored .080 over. I've checked once this year and have gotten a little over 15 with a Brumfield head. Of course that is with lots of town driving and a long parade thrown in. We have a trip this weekend and I plan on checking it again. Hope to do be back up around 20+. While your will probably never get 24, with the right set up you might come close.
JBR
 
Gary Gregory said:
Any difference in mileage between 100% gas and the stuff with ethanol? I just got my 30 coupe last month and been running premium with ethanol...haven't tried the 100% yet.
Click to expand...

Ethanol sort of has to get worse mileage. Two ways to look at the chemistry of the situation: (1) ethanol is 1/3 by weight oxygen, which doesn't burn, or (2) one of the two carbon atoms in ethanol is already partly oxidized, on its way to CO2.

Steve
 
You will probably get best mileage with unleaded regular without the ethanol. With up to 10% ethanol you will likely lose about 2 mpg to 4 mpg.

With total ethanol your mileage will drop by about 50 %.

My experience anyway.

Dennis L Oberer
Green Bay WI
 
the only A I know of getting 24mpg was a roadster pickup using real gas on highway I-5, which is flat, driving down wind. Most A's used to get 20 in good running condition, but with ethanol in there they get around 18 now on the highway, 16 in town, as low as 14 on the heavy cars.
 
Here's an example of the type of reports I have received from customers over the years, should you choose to believe it. The report was by customer Peter Crosby in a thread on the Ahooga.

"I am running a Brumfield 5.9 CR head on my 1931 SW Fordor. I would not run anything else. I now get about 22 miles per gallon and can climb hills in third gear where I could not before."
................

As I mentioned in my post above, you will get better mileage with a Brumfield Head.

Now as also mentioned, you may NOT get better mileage if you have a heavy foot or don't know how to drive, i.e., improper use of the spark lever, lugging or loading the engine, etc., etc..

Moreover, you can't have a halfway worn out engine or an overly rich carburetor, dirty spark plugs, etc., etc., etc., .... just like it is with an all stock engine and expect good mileage whether you have a Brumfield Head or any high comp head.

Larry B.
 
Thank you everyone...
Alot to consider....
money is very tight right now... so thats why my big concern more or less.
Would a single downdraft (94) make an improvement compared to a single or dual updraft?

I'd just love to have a more or less stock model-A one way or another. So I will gradually build the truck anyways. Just trying to sort out an excuse to do it sooner...

Thanks
Zach
 
SUHRsc said:
Thank you everyone...
Alot to consider....
money is very tight right now... so thats why my big concern more or less.
Would a single downdraft (94) make an improvement compared to a single or dual updraft?

I'd just love to have a more or less stock model-A one way or another. So I will gradually build the truck anyways. Just trying to sort out an excuse to do it sooner...

Thanks
Zach
Click to expand...

If money is tight and you value "more or less stock", those are two good reasons to definitely stay with the updraft Zenith. The downdraft would require you to buy a new manifold too. Most people go to other carbs to get more power, which means less mileage. I get superb mileage with my new/repro Zenith-1, especially compared to club members using the Allstate/Marvel/Schebler carbs. They love the performance of those square-bowl carbs, but I reliably take 1-2 gallons less per fill-up, a difference that's hard to believe even when you see it. That's in my heavy town sedan, too.

If you have any, use your discretionary funds to get a high compression head, one of those brand new Zeniths, and a thermostat--all of those will help.

Steve
 
Thanks Steve...
I am defonitely considering some form of updraft....
I actually have the single downdraft stuff sitting here though.

This isn't my first old car, just my first attempt at something basically stock.
This one below is a thirsty bugger!
b015.jpg
 
MPG vs MPH

I have a homemade mileage tester and have done some tests at various speeds. Here is a graph showing the MPG vs MPH. I also did a 1/2 mile start up test with a cold and then with a warm engine. The cold engine start up resulted in about 9.8 MPG for the 1/2 mile. The warm engine resulted in 18 MPG for the same 1/2 mile test. The test was done in my 1931 Pickup which has a B engine, B carburetor, A distributor, Mitchell Overdrive.

Bob
 

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Re: MPG vs MPH

Bob Johnson said:
I have a homemade mileage tester and have done some tests at various speeds. Here is a graph showing the MPG vs MPH. I also did a 1/2 mile start up test with a cold and then with a warm engine. The cold engine start up resulted in about 9.8 MPG for the 1/2 mile. The warm engine resulted in 18 MPG for the same 1/2 mile test. The test was done in my 1931 Pickup which has a B engine, B carburetor, A distributor, Mitchell Overdrive.

Bob
Click to expand...

Your chart explains why I always get 14-16 range. Think it's wind resistance.
 
Zach, if it was me I would put in 3:54 rear gears and a 5.5 or 6 high compression head. With that combination to get the most mileage I would add a Mitchell overdrive and some new balanced tires with 35# pressure. I have a 5.5 head and Mitchell in my 29 coupe with the 3.78 rear end and the on the road average is over 20mpg. The 30/31 pickup is lower in height so it should have less wind resistance.
 
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