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lesterwa58 09-19-2010 09:56 PM

Flathead Gas Mileage
 

I am wondering if someone out there might have an idea as to how I can improve my gas mileage, I am getting like 4 miles to the gallon. Some background. I have a stock 59AB engine with two 94 carbs, that have no been touched, in a Model A roadster. There are no fuel leaks, there is not smoke and the exhaust pipes (2) are clean, and there is no smell of gas at any time whether I am moving or at an idle. I have an electric fuel pump, but the fuel runs through a pressure regulator set a about 2.5 pounds. I have let this engine idle while sitting on my concrete pad and there is no sign of any leaks, even when I get under the car and look. The compression ratio in each cylinder is about 125.
Any help I can get would be appreciated as this kind of low gas mileage really prevents me from driving this car any distance. if I go 25 miles I use 6 gallons of gas.
Thanks, Wes Jones, Cle Elum, WA

quickgene 09-19-2010 10:23 PM

Re: Flathead Gas Mileage
 

Sounds like my 396 Camaro with 4.11s.

I would say shitty carbs or bad distributor.

If gas isn't running out the pipes, you have a high gear that you use and your eyes don't burn when driving it I would get a good distributor in it. At this point you will have a tough time making it worse. A good distributor is a good update even if it isn't the problem.

What do the spark plugs look like ?

A good pair of carbs is a little more spendy but it may come to that. Multiple carb setups are great but they can easily give these results. I guess if you have a buddy that will borrow you a single carb manifold with a proven good carb you would know right away.
Gene

52merc 09-19-2010 11:15 PM

Re: Flathead Gas Mileage
 

what rear end do you have in it

ken ct 09-20-2010 02:10 AM

Re: Flathead Gas Mileage
 

I would ask what model # carbs are you using and what dist?. What do these carbs have for jetting,what power valves,where is the link for the accel. pump are you trying to run progressive linkage on this or straight linkage.Could be poor rebuilding or poor choice of parts. Give us more info. ken ct.

George/Maine 09-20-2010 08:44 AM

Re: Flathead Gas Mileage
 

Do you have a home made tank and how many gallons in tank.Drive it 50 miles and refill it.I have 265 mercury with 2 97s and 2.78 gears and get 18 to 20 mpg.Some times the tanks are made wrong and you can,t get a good reading.

Brendan 09-20-2010 10:26 AM

Re: Flathead Gas Mileage
 

do you have a vacuum advance?

FL&WVMIKE 09-20-2010 11:13 AM

Re: Flathead Gas Mileage
 

lesterwa58 ......................
Like someone said, try a single manifold off a good working car, if you can. Dual carbs. sure look great, but they can be a pain. Let us know.
MIKE :)

gmc1941 09-20-2010 11:25 AM

Re: Flathead Gas Mileage
 

Block off one carb between the carb and the manifold. You could be over carbed. The excess gas could be washing down your cylinder walls NOT GOOD. Any gas in your oil? Clutch slipping? Brakes dragging. Will the car roll easily pushing it on even ground. Ford said with the orginal system 15-20mph which I think this is far fetch but depends on your driving habits. Any time you modify, you change the characteristics of the economy of the car. Sometimes for the better and sometimes for the worse. More of my 2 cents, I wish I had more sence.. Gordon

richard crow 09-20-2010 12:12 PM

Re: Flathead Gas Mileage
 

i said it once & i say it again the more none stock crap you add the worse they run they may go faster but that,s it. for good milage,good idle easy starting & less overheating leave it stock

Karl Wolf 09-20-2010 12:13 PM

Re: Flathead Gas Mileage
 

You can use a timing light to see if your distributor advance is working, look to see if the light moves on the pulley as you increase rpm, if it is, look to carbs... People have lots of single carb manifolds, (I've got six or seven) you could set up each carb singly and see what you get from each one... Karl

Fourdy 09-20-2010 12:44 PM

Re: Flathead Gas Mileage
 

Sure should get more than that. Just returned from a 400 mile round trip and got 17 mpg. Blown 276, C4, 3:36 rear.

These guys will help you get it squared away.

Fourdy

Mike51Merc 09-20-2010 02:22 PM

Re: Flathead Gas Mileage
 

I find it hard to believe that it can consume that much fuel and still be running OK.

I have a 255 Merc with twin Stromberg 48s, direct throttle linkage, 4:27 rear with OD and get nearly 20 MPG.

Tom's36coupe 09-20-2010 02:30 PM

Re: Flathead Gas Mileage
 

I am running twin Holley carbs with a big camshaft and mallory electronic distributor , 3 speed with 3:55 rear gear. Around town I think I might be getting about 10-12mpg, but my foot is always in it! If I took it easy it might get 15-17 which I think is pretty good. Two great people that I know on this board are Ken ct and Charlie ny for carbs and bubbas speed shop for the distributor. Those two things are most likely to blame, unless you are like me and can't get enough of the sound of our Flatheads! lol....:D

Bassman/NZ 09-20-2010 03:55 PM

Re: Flathead Gas Mileage
 

Quote:

Originally Posted by Tom's36coupe (Post 85207)
I am running twin Holley carbs with a big camshaft and mallory electronic distributor , 3 speed with 3:55 rear gear. Around town I think I might be getting about 10-12mpg, but my foot is always in it! If I took it easy it might get 15-17 which I think is pretty good. Two great people that I know on this board are Ken ct and Charlie ny for carbs and bubbas speed shop for the distributor. Those two things are most likely to blame, unless you are like me and can't get enough of the sound of our Flatheads! lol....:D

So YOU'RE the guy they call Leadfoot Louie? :D

Walt Dupont--Me. 09-20-2010 07:04 PM

Re: Flathead Gas Mileage
 

From Me. to Cape Cod Ma. all turnpike with my 40 coupe, 276, track cam, two 94's on super dual intake, 5.0 PV 49 jets, milled Edelbrock heads, 150# compression, T-5 trans, 9in. rear 3:50 gears, 60mph with a GPS, 2000 RPM, 24MPG Almost as good as a UGO. Walt

Tom's36coupe 09-20-2010 07:55 PM

Re: Flathead Gas Mileage
 

Leadfoot Louie here! Just filled up today and I averaged 9mpg! Oops, guess I like to run it up to 4000rpms too many times? This week I will try to take it easy and see where the mileage goes. Running 54 jets with no pvs, but with 380 lift and 260 duration I don't think my car is going to be a MPG champ,,,,:eek:

av8paul 09-20-2010 08:18 PM

Re: Flathead Gas Mileage
 

Quote:

Originally Posted by Tom's36coupe (Post 85377)
Leadfoot Louie here! Just filled up today and I averaged 9mpg! Oops, guess I like to run it up to 4000rpms too many times? This week I will try to take it easy and see where the mileage goes. Running 54 jets with no pvs, but with 380 lift and 260 duration I don't think my car is going to be a MPG champ,,,,:eek:

I don't know what my mileage was, but I did a run to a show West of Boston on Saturday. I had my new/rebuilt 97's from Uncle Max on for the first time. It runs so good, I couldn't keep my foot out of the carbs. Every light required at least 3,000-3,500 RPM before I shifted to high. I used 3/4 of a tank (10 gallon tank) on the run up there. I filled up before I came home and drove with a little more sanity and used about 1/2 tank of gas. Guess a light foot pays.

Huff 09-20-2010 08:32 PM

Re: Flathead Gas Mileage
 

I don't see how a flathead Ford can even run using that much gas.It has to be leaking some place.

flatmotor40 09-21-2010 05:26 AM

Re: Flathead Gas Mileage
 

just drive it and enjoy don't wory about mileage after all BP says they are broke,tuff

38 coupe 09-21-2010 09:09 PM

Re: Flathead Gas Mileage
 

I have observed anywhere from 12 to 22 with stock flatheads. The earlier cars seem to get worse mileage. My 85 horse 37 gets about 15 at a steady 60, my father's overdrive equipped 50 got 21 at 70.

I think you should really look at your carburetor jet and power valve settings as well as your distributor advance curve. Make sure you are not running a stock 49-53 distributor with dual carbs.


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