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Discussion Starter #1
I try to figure out my Fuel Consumption Probs- )

What is the Capacity of a Fuel Tank for a 62 Ford Galaxie Conv.?
How much Miles could I drive with normal cruisin Style - behaviour?

Which function does the Power Valve in a Autolite 4100 - 1.12 have? And what would occur if it is failin?

My Car droves good, starts well in cold temperature, and do not stutter in acceleration or unequal engine behaviour...

Have to admit often drive short cruises...-( but which distance are short cruises for a 390 FE???

thanks
Oliver from Germany - Cologne
 

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My new rebuilt 390 and 4100 carb get me 9 mpg, city or highway, no difference. I'll fill up my 20 gallon tank when it gets down to 4 gallons, that's 150 miles between refills. I have a pretty heavy foot though, because I like hearing the rumble out of the glass packs when I stomp on it off traffic lights.

Some folks claim 15 mpg with a similar set up. My car is like yours: starts, runs, accelerates just fine. I attribute my bad mileage to bad driving habits.


The power valve opens due to a set vacuum level. The vacuum sucks fuel into the intake as long as you are accelerating. It is different action than the accelerator pump, which only gives a one-time squirt. If the PV or its gasket is bad you could be leaking fuel down into the intake.
 

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From stop light to stop light, I'd rather have an FE. But with that old 289 I had, I could squeeze 400 miles + out of a tank on a road trip! (At the speed limit of coarse....but what fun is that?)
 

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Discussion Starter #6
Have to ask about the Power Valve in an Autolite 4100 again... what kills a Power Valve? Only Backfires for example? Or standing in Garage at Winter Sleep?

By the way - any Experience with NGK Iridium Spark Plugs? I often drive Short Cruises - to buy Cigarettes or Bread. had the Problem with carbon fouling.
I have heard the NGK Iridium Spark Plugs will do a better job due to Short Cruises than other Plugs... your Experience here?

I guess if Power Valve fails then Fuel Consumption and Carbon Fouling occurs.
Additionaly how can Driving mixture made "leaner"? I think at starting up the Engine as the Start Procedure Mixture is too rich... Should there switch the Choke to much more Lean position - one or two Marks?

Olli
 

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From stop light to stop light, I'd rather have an FE. But with that old 289 I had, I could squeeze 400 miles + out of a tank on a road trip! (At the speed limit of coarse....but what fun is that?)
My 347 stroker with a 5 speed in my 65 gets 18mpg cruising the speed limit. Of course it still has the stock 3.00 gears and 28 inch tall drag radials and a .68 overdrive so at 70 it's only running around 1250 rpm.


Nd to the OP. yes back fires can kill a power valve especially an old crusty one. This would cause a rich condition that will fuel foul plugs. Is your choke opening up all the way when warmed up? If all that stuff is good are you sure your jetting isn't too fat.
 

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Discussion Starter #8 (Edited)
The Choke is opening completely. Which Jets be prefered for a Autolite 4100 1.12 on a FE 390 - Primary and Secondary? Stock Engine from Factory - Compromize between Performance and Fuel mpG.

I know the Starting Mixture when Choke is nearly closed has to be rich. To lean this mixture I have to turn the Choke Cap to lean - right? Helpful?

I have probs with Spark Plug Fouling - I´m sure cause of the rich Mixture on Starting and Short Cruises of course....

I did or do not have backfires... Meantime I´ve ordered me a Carb Overhaul Kit. Including PV too...

Does the FE 390 tend to carbon Fouled Spark Plugs when Spark is too weak, rich Mixture occured and the PV fails? Or if Distributor Cap and Rotor starts to fail? My FE 390 is a little Diva cause of this.
It registrates directly one of these Parts are not in the correct Shape.. LOL


Olli
 

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Maybe it will improve after a kit. I had, still have, gas boiling issues on my 390 so adjusted the rear floats down a lot and front some. The front would over flow and run back to the rear and over fill it then i'd be hearing the hiss of gas dripping in the carb. But far as mileage it was fine, back then 10-12 i guess. Now i get bout 15-16 on the highway and probably 10-12 in town. But i changed to a 2.75 rear end. Some or i should say my dad and uncle always used one step hotter plug than the books called for also. Been so long i can't remember if i did that on mine last time or not. I'm probably due for some but it's running well.

Back firing will kill the power valve but when i was having back firing issues it was the holley not the 4100, same problem that cause the backfire with the holley didn't on the 4100. I would also check the little 6 inch piece of fuel hose from hard line to the gas tank, it may be cracked and leaking. Also at the fuel pump if you have any hoses.
 

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Discussion Starter #10
thanks for answer - but I did have no backfires in any kind....

Which Jet Sizes for Primary and Secondary would be ok for performance on a Cruiser like the Galaxie 500 on a Stock FE 390 -built in ´62?

Any driving results for NGK Iridium Spark Plugs?

Ho to lean the mixture in Idling up the Machine? Turn the Choke Cap two notches lean or align the Idle Mixture Screws?

I think it has to be possible to drive Short Cruises from Time to time without having too much Carbon fouling on the Spark Plugs - agree??

Oliver
 

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Stock Engine from Factory - Compromize between Performance and Fuel mpG.
Olli, folks would like to think that, but reality is that engines were tuned depending on what emission parameters the Government dictated, or what the market demanded. So, while max power was usually pretty good, average mileage would usually be a bit low (often the ignition timing was the cause of much of the loss) to keep emissions - including odors - low. While we have "learning" EFI today, these production cars were only adjusted for the average car, and not tuned to each. Some were great, and others were rather poor. After 50 years and changes in fuel, most are rather poor.
Does the FE 390 tend to carbon Fouled Spark Plugs when Spark is too weak, rich Mixture occured and the PV fails? Or if Distributor Cap and Rotor starts to fail? My FE 390 is a lil Diva cause of this.
No, the 390 should not tend to carbon-foul the spark plugs. If it does, something is in poor condition or poor adjustment, or both.

David

[EDIT] I should make clear that both carburetors and EFI can be tuned for best power and best mileage. It is commonly heard that a carb is tuned for one or the other, but to say that it cannot do both with the same tune is false. Best mileage along with max power when your floor it is entirely possible, and when tuned fully and properly, it should be.
 

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Oliver, I run a Holley 780 carb on my 410 FE. My primary jets are 74 and my secondary jets are 76. On my old 390, with a 4 speed and 3.00 rear end, I averaged 10 mpg. My 410 is too new (less than 500 miles) so I don't what I will average but I think it will be around 10 again.
 
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