Technical Why Is My MPG So Low?

In my experience Ford flatheads are not great on gas mileage. I believe a ‘53 Fordomatic starts in 2nd gear when in drive so not exactly great for performance or mileage, especial around town. It might be good to check the tune-up stuff as well as the proper carb and match to the distributor.

 

that is simply not true. I had an old Datsun pickup with points. I checked my mileage constantly so I would know when it needed a tune up. had a pen, notepad and a calculator in the truck. never needed a receipt and never a reason to keep them or even take one. how much gas you got is right there on the pump.
we are giving pointers on tune ups when it could be a math problem.

 

You're arguing about receipts. That's pretty damn funny. Have a good one.

 

Post a few pics of the engine. One of the carb showing any numbers it may have on it. A shot of the entire engine and even the old plugs. That would give everyone a chance to add to their thread count while disagreeing on what the issues are.
Your not being ridiculed, it's the grumpy old men style of humor. If they weren't trying to help you the post would be ignored.

 

Flathead tune up shops don’t exist any longer. If the OP lacks the knowledge and tools, I’d recommend contacting a local car club where he may very likely find the help he and his Flathead requires. That engine should get double that mileage and be more fun to drive.

 

Must be close to spring the curmudgeons are crawling out of their caves to shake their fists at people on their lawns a day early.

 

In my local area, some younger (<40) guys have a shop doing just this. They do mechanical and machine work (as well as some metalwork) on vintage engines and have collected a wide range of tune-up and machine equipment, can pour babbit, completely rebuild vintage engines, etc. These shops are out there, but you have to look for them.

They kind of stumbled into doing this. The one owner worked at several restoration shops and realized that nobody knew what to do with the drivetrains of antique cars, so cars would have a fully restored body and nothing done to the drivetrain. They do lots of tune-ups and all the stuff nobody else knows how to do anymore.

The antique clubs should know if there's someone who does this stuff in your area.

They have a YouTube channel too. Strong's Garage - YouTube

 

So how much do you drive the car? If only a few miles a year does it really matter.
Have fun with it.
If you want to drive it more than 500 miles a year , get it checked out by a shop that knows old cars like yours.

 

Strong's rocks. Scott at Cold War Motors turned me on to those guys.

 

I'm not familiar with the ap,
does it use gps tracking?
and fuel measured fill up to fill up?
if yes than those numbers may be accurate
but if you are relying on the odometer what rear gear ratio and tire size, what gear are you in most, is this slow stop and go driving around town? are the plugs black or oily?
like said are brakes dragging, tires under inflated, front end out of alignment?
there are a hundred little things that could easily add up to a few mpg

 

A link to flat head tune up specs http://www.vanpeltsales.com/FH_web/flathead_tuneup49-53_239-255.htm
A mini abacus for the glove box
https://www.amazon.com/Abacus-Decor...pcontext&ref_=fplfs&psc=1&smid=A1MD5X7O7R4L4C
Dan

 

They're both within about 30 minutes of me. Matt from Strong's actually lives much closer than that to me.

 

Just to throw a wrench into the discussion: My dad and I were having a chat about gas mileage and he says.."I bet you won't believe this but when your grandfather's 50 ford coupe was a year old, I drove it down hiway 97 from northern Oregon to Eureka, California and got 24 MPG!"
Granted, the car was only a year old and it was a V/8 overdrive car and there was no wind to speak of but he was completely blown away with these numbers. You'll have to take it up with him and he died in '05.

 

Alright, I'm no Flathead guy whatsoever, but I do build quite a few engines, so just reading the OP's posts and seeing he's been a member for quite a few years, I'll ask a couple questions:

Has it always gotten the 7 mpg or is this something new? I'm assuming you've owned the car for a while. If it got 10 mpg last year or even last month and all the sudden its getting 7 mpg, we can go from there diagnosing knowing something is newly wrong or different, and it's not just worn out or something else that it's been for a long time.

I saw in your second post you said you think you might be hearing "valve tap". Is it possible you're hearing an ignition miss, like a burned plug wire or a cracked plug sparking? I just helped a guy with a broken porcelain on one of his plugs fix a poor running/bad fuel mileage problem. He had spark shooting from the plug to the head, and he could see and hear it.

If it doesn't seem to burn oil, miss, or run rich, just a semi-educated guess we've got a timing issue, either base timing or advance curve. Once again, I'm not a Flathead guy so I'd defer to one of them for where base timing and advance should be, but every other engine I've been around would make me guess ignition timing is off somewhere, most likely retarded on base or the mechanical advance isn't doing its proper thing. And once again, that's assuming the engine itself is healthy along with everything else.

(Edit: I skipped from page 1 to 3 on accident. I see on page 2 there's a lot of other guys suggesting timing and advance. Great minds and all that, although I'd hate to put myself in that group....)

 

Choke, set it when eng is warm to all the way open and take what comes when it's closed

 

You seem to be more worried about the high fuel consumption than the poor performance. I think most guys here on the HAMB would be more focused on getting it to go well. Do what you have to do to get the power output where it should be and I will bet that the fuel problem might just take care of itself.

 

Just went through this thread. Doubt the OP is coming back. Had a serious question but is not automotive inclined. Trying to diagnose without more info is difficult to say the least. Gas receipts were for amount of fuel pumped, and then used to calculate MPG using miles driven.
I’d start with when was the last time any preventative maintenance was done. Plugs, points, fuel filter, fluids, wheel bearings, brakes, etc. Almost certainly, it’s running rich = fouled plugs = poor engine perf. Running rich is a carb adjustment issue which will likely be outside the skill set of OP.
As others have suggested, best to find a club/group in the OP’s area to have a look at it.

 

this is a here's what "I" think, and here's what I would do and why...

first off.... I'd start running Lucas fuel treatment in the fuel tank... what this will do is clean the entire fuel system... tank included... I would start with a new fuel filter....what I think is happening is this...you have restrictions in the fuel system...when the motor demands fuel it's not getting whats needed so it goes right past cruise mode and into wide open throttle and dumps fuel.... in cruise mode, thats where you get the best MPG....lucus will also lube up the upper cylinders and clean the valves.....

so for "ME"....being 72 and fixed this before...including 292 motors ... I start the motor... let it warm a little...turn the idle up to 2k or so and slowly dump about 5 big cups of water down the carb,,, go slow to not kill the motor.... after that... (and this is assuming that you put a new fuel filter)...I would get a quart of marvel mystery oil, and do the same thing.....it'll smoke like a bbq while doing this...and again... go slow to not kill the motor...

 

the next thing that goes on with these motors....sticky valves.... I would put 2 quarts of marvel in the motor... and let it sit at a faster than idle and run....keep an eye on it as to not let it over heat.... some times I keep a garden hose handy and spray the radiator...... just keep an eye on the temp...somes times I do this for an hour , shut it off let it set and a few hours later do it again...and the results are with out doing timing, plugs, points or crb adjusting get a reaal easy start, and smooth idle...but anyway...... once you are there.....change the oil...and from then on put 1 quart of marvel in at every oil change,,,, the marvel will eliminate sticky rings and valves...and keep the motor clean inside.... it will also seat leaky oil and compression rings...

and the lucas.....allways add to old cars ass it helps them with the lead free fuel....and helps cushion the valve seats....

 

it's agroup that are fine with their group....and attact any new person that comes in their yard...some of the comments made to me here if we were in the bar... one of us would have got an ass whomp'n...I grew up on talk shit get hit... I talk to a lot of hot rodders in vegas /cal/ and utah... they all say the same thing... I go on the hamb and look, but never post.. and the over under for me was I wouldn't last a week..... but... i sift through the bull shit... get heckled so all their secret hand shake guys will give them likes.. one of them starts, and they all come running,.... there's some good people on this board that in person would do anything to help another car guy... but keep quiet on the threads...

 

Exactly. Plugs themselves don't matter as long as the gap is more than zero and less than .25

 

No low compression flathead is good on gas. You pair it with a big honkin automatic and it's gonna get worse. The pre-war cars only get decent fuel economy because they're so light.

 

interesting...

 

Hello,

110 hp for a flathead motor seems like a miracle. As an owner of a stock 80 hp flathead in my teenage 1940 Ford Sedan Delivery, it can be a rough way to drive in modern… 60s traffic along the So Cal coast on the weekends. So, despite where you live, there is always traffic nearby leading into big cities. Or simply, just in your neighborhood.



We were limited to 80 hp with our income status, teens… But, if we had more horsepower, we could have made our coastal road trips quicker and no worry about the “slow lane drivers” which we were, fully loaded with our surf/camping/food stuff along with our at least two 40-50 lbs longboards.

So, it came down to weekend driving during the school year and during the summers, a little more freedom. But, it was not an old hot rod to take to the local mountains during the winters. Why??? It was a lack of horsepower during our hill climbs on Coast Highway heading South through Laguna Beach at first. Then Dana Point. Finally as we moved farther South to San Diego, the Torrey Pines PCH highway steep hill climb along the beach that was just awful. A full third to second to first gear in the slow lane, following those cars pulling trailers and trucks in low gear.

The lack of horsepower kept my foot in the gas at most times going uphill, changing lanes and trying to pick up enough speed to be able to flow with the usual traffic. Sometimes, I was the only old car going down, then up a steep highway along the beach in first gear. It was due to someone changing lanes and making me downshift to second, then first to be able to make the climb up the steep grade to get to the top of the coastal hill.

Jnaki

So, it was a definite “use more gas” as the pedal was constantly pushed down. Now, not saying your driving in your area causes poor gas mileage, but have you looked at what you are doing when in traffic and or on slight hills? Perhaps, 100 hp is not enough for your car to keep up with traffic and you are pushing down more on the gas pedal. Your motor might be in great shape, but with the automatic transmission trying its best, it might be difficult to keep up.

So, unknowingly, you are stepping on the gas pedal more than you think. So, more stepping on the pedal equates to more gas usage and therefore poorer gas mileage. YRMV

If I had more horsepower in my flathead powered sedan delivery, fully loaded down, there would not have been more gas usage, just trying to keep up with the flow and not get stuck in the slow lane every time. Local driving in traffic does cause different driving styles, just to adjust to the flow.

 

I just pulled those numbers out of my ass. I'm just saying as long as the gap is something that will run reading the plug residue for lean/rich matters more than the plug itself.

 

Yesterday, I dug out some early ‘50s Motor Trend road tests and was surprised at the good mileage they got in automatic and overdrive versions, 24 mpg on the highway was about what they saw. But that could get down to 11-12 in “heavy traffic”.

 

@Yardbirder Try Ford Barn.

 

Years ago my Uncle told me how to get better gas mileage than your buddies; let them tell you what they get first.

 

The first liar doesn't stand a chance.

I have a buddy that insists he can figure out his gas mileage by what the gauge tells him is in the tank. Good luck with that.
I have two vehicles that use the same 16 gallon fuel tank part number from the same vehicle line with the same part number fuel sending unit. With one, I can drive on a designated 100 mile drive and the gauge reads 3/4 tank of gas is left, but the other one that same designated 100 mile drive, the gauge says I have used a little more then a 1/2 tank of gas. The problem is, when both get down to showing only having a 1/4 tank of gas, both take the same amount of fuel. The fuel mileage difference between the two vehicles on that designated 100 mile drive is, the 1st vehicle gets 20 mpg, the second vehicle gets 19 mpg. Both vehicles have been driven on that designated 100 mile trip several times, and both have recorded consistent fuel mileage, and both make the return trip on the same tank of fuel. If you assumed you could determine the fuel mileage between the two vehicles based on what the gauge tells you at 100 miles, you would be way off.

 

Might need an arc welder to light a 1/4 inch gap!