The Ford Barn

700rpm · 10-02-2013, 06:51 PM

Quote:

Originally Posted by Duffy1

What is the gas mileage.

About 15 mpg. I've never been able to get much more than 16 in any Model A.

Duffy1 · 10-02-2013, 10:46 PM

If this is hwy mileage you should get around 19.You carb may be running rich.I checked the jets in my carb and they were all at of spec on the rich side. Some times the repro jets are not even close to spec.

700rpm · 10-02-2013, 11:47 PM

Yeah, that's what I think too, Duffy. But my plugs are the right color and I have tested all the jets and I'm on spec. I don't understand why I can't get better mileage, except I notice when I can burn non-ethanol I can get up to about 18 and 19 mpg. So I'm gonna blame the corn.

Dave in Boise · 10-03-2013, 12:00 AM

Maybe too obvious, but perhaps a bit too much MMO or other Fuel additive? I would suspect that for a short trip under 15 or so miles, the cylinder temps may not be getting hot enough to burn out any oily residue from a fuel treatment.

Hope it helps

- Dave

700rpm · 10-03-2013, 12:07 AM

Quote:

Originally Posted by Dave in Boise

Maybe too obvious, but perhaps a bit too much MMO or other Fuel additive? I would suspect that for a short trip under 15 or so miles, the cylinder temps may not be getting hot enough to burn out any oily residue from a fuel treatment.

Hope it helps

- Dave

I don't use any additives.

colin1928 · 10-03-2013, 12:37 AM

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Hi I have a simular problem as you and while took me ages to find it turned out to be inlet manifold leak on just 1 flange causing just 2 cylinders to run lead and hot and 2 cylinders to run rich
this may not be your problem I had the same issues
Colin

tbirdtbird · 10-03-2013, 09:50 PM

I get much better mileage whenever I can get non-polluted fuel for any of my cars, including my '09 Silverado...and the engines run smoother....

lesse...more miles per gallon means less pollutants per mile means the EPA should be happy...arg, what was the purpose of polluted fuel again ???

700rpm · 10-03-2013, 10:26 PM

Quote:

Originally Posted by tbirdtbird

I get much better mileage whenever I can get non-polluted fuel for any of my cars, including my '09 Silverado...and the engines run smoother....

lesse...more miles per gallon means less pollutants per mile means the EPA should be happy...arg, what was the purpose of polluted fuel again ???

Makes the corn corporations richer.

700rpm · 10-03-2013, 10:27 PM

Quote:

Originally Posted by colin1928

Hi I have a simular problem as you and while took me ages to find it turned out to be inlet manifold leak on just 1 flange causing just 2 cylinders to run lead and hot and 2 cylinders to run rich
this may not be your problem I had the same issues
Colin

This is an interesting theory, because I had some trouble seating my manifold gaskets last March. I have new gaskets now, and I may just put them on and see if that helps.

Duffy1 · 10-04-2013, 02:47 PM

If you can adjust the air mixture screw on the carburator per spec (1 1/2 turns out ? ) then the intake manifold is probably not leaking unless it is a very very minor leak. If the air screw can only be turned out a small amount then you probably have a leak at the intake manifold . Spray some oil around the intake manifold while the engine is running and see if the rpms change .

700rpm · 10-04-2013, 03:53 PM

Quote:

Originally Posted by Duffy1

If you can adjust the air mixture screw on the carburator per spec (1 1/2 turns out ? ) then the intake manifold is probably not leaking unless it is a very very minor leak. If the air screw can only be turned out a small amount then you probably have a leak at the intake manifold . Spray some oil around the intake manifold while the engine is running and see if the rpms change .

Air mixture screw seems correct. No change in the rpms when tested as you suggest. Hmmmm...

CarlG · 10-04-2013, 05:32 PM

Quote:

Originally Posted by 700rpm

... I don't know how to do a leak-down test. Can someone explain?...

You need a tester like this one I got from Amazon:
http://www.amazon.com/s/ref=nb_sb_no...rds=B0030EVL60

Mitch//pa · 10-04-2013, 07:54 PM

Quote:

Originally Posted by Duffy1

If you can adjust the air mixture screw on the carburator per spec (1 1/2 turns out ? ) then the intake manifold is probably not leaking unless it is a very very minor leak. If the air screw can only be turned out a small amount then you probably have a leak at the intake manifold . Spray some oil around the intake manifold while the engine is running and see if the rpms change .

play in the carb throttle shaft can also cause this

10-02-2013, 10:46 PM	#22
Duffy1 Senior Member Join Date: May 2012 Location: Mo. City , Texas Posts: 725	Re: What's causing this carbon buildup... If this is hwy mileage you should get around 19.You carb may be running rich.I checked the jets in my carb and they were all at of spec on the rich side. Some times the repro jets are not even close to spec.

10-02-2013, 11:47 PM	#23
700rpm Senior Member Join Date: May 2010 Location: Portland, Oregon Posts: 5,906	Re: What's causing this carbon buildup... Yeah, that's what I think too, Duffy. But my plugs are the right color and I have tested all the jets and I'm on spec. I don't understand why I can't get better mileage, except I notice when I can burn non-ethanol I can get up to about 18 and 19 mpg. So I'm gonna blame the corn. __________________ Ray Horton, Portland, OR As you go through life, keep your eye on the donut, not the hole.

10-03-2013, 12:00 AM	#24
Dave in Boise Senior Member Join Date: May 2010 Posts: 330	Re: What's causing this carbon buildup... Maybe too obvious, but perhaps a bit too much MMO or other Fuel additive? I would suspect that for a short trip under 15 or so miles, the cylinder temps may not be getting hot enough to burn out any oily residue from a fuel treatment. Hope it helps - Dave

10-03-2013, 12:37 AM	#26
colin1928 Senior Member Join Date: Mar 2013 Location: Australa Melbourne Posts: 878	Re: What's causing this carbon buildup... Sponsored Links (Register now to hide all advertisements) Hi I have a simular problem as you and while took me ages to find it turned out to be inlet manifold leak on just 1 flange causing just 2 cylinders to run lead and hot and 2 cylinders to run rich this may not be your problem I had the same issues Colin

10-03-2013, 09:50 PM	#27
tbirdtbird BANNED Join Date: May 2012 Location: inside your RAM Posts: 3,134	Re: What's causing this carbon buildup... I get much better mileage whenever I can get non-polluted fuel for any of my cars, including my '09 Silverado...and the engines run smoother.... lesse...more miles per gallon means less pollutants per mile means the EPA should be happy...arg, what was the purpose of polluted fuel again ??? __________________ '31 180A

10-04-2013, 02:47 PM	#30
Duffy1 Senior Member Join Date: May 2012 Location: Mo. City , Texas Posts: 725	Re: What's causing this carbon buildup... If you can adjust the air mixture screw on the carburator per spec (1 1/2 turns out ? ) then the intake manifold is probably not leaking unless it is a very very minor leak. If the air screw can only be turned out a small amount then you probably have a leak at the intake manifold . Spray some oil around the intake manifold while the engine is running and see if the rpms change .