Question on fuel consumption of my BN6

BN6_2197

Jedi Trainee

Offline

• Aug 13, 2014

• #1

Hi gents,


depending on driving style and weight of the co-pilot my BN6 uses 18-20 liter fuel per 100 km. In my perception that is pretty much. I refurbished the carbs last year without any noticable improvement. Also checked the emission, but nothing remarkable on that.

Is that much consmption expcted? If not, does anyone have an idea how to proceed to improve the situation?

Volker

 

bighealeysource

Luke Skywalker

Bronze

Offline

• Aug 13, 2014

• #2

Hey Volker,
Gonna have to convert that over to gallons for us Yanks ! I had a 58 BN6 that did average around 25 miles per gallon when driving around a constant 55-60 mph. Would think usual would be in low 20's. One thing you might check is if you are running too rich which would impact the mpg. On the other hand though, if it's running good, don't touch it as I like to practice the "if it a'int broke, don't fix it" philosophy !!!
Regards
Mike

 

Keoke

Great Pumpkin

Offline

• Aug 13, 2014

• #3

Hi Volker
Sounds about right given the differences between the Liter and The Imperial gallons
Odometer accuracies, tire sizes and driving styles.

 

Last edited: Aug 14, 2014

OP

BN6_2197

Jedi Trainee

Offline

• Aug 13, 2014

• #4

Mike,

I checked if I am running too rich by measuring the emission of the car. According to my garage I am running more less than too rich. I share your opinon that you should not touch a running system. My car is indeed running fine.

Did I understand it right, that in your opinion 18-20 liters per 100 km (for a German guy) is not neccessarily unusual? When driving on a high way constantly about 60/65 mph at 3000 rpm the car consumes a little bit less (15-18 per 100 km).

Regards,

Volker

 

Keith_M

Jedi Knight

Offline

• Aug 13, 2014

• #5

Assuming 4 liters per gallon and .6 miles per kilometer, 20 liters/100 km comes out to be 5 gals per 60 miles, which is about 12 miles/gal. Most healeys get around 20 mpg I think. I'd say you're either running really rich or leaking gas.

 

OP

BN6_2197

Jedi Trainee

Offline

• Aug 13, 2014

• #6

Keith,


I checked if I am running too rich by measuring the "CO-Value" by putting a sensor into my exhaust pipe. It seems to be good according to my garage. What is a "good" CO-value from your point of view? By the way: In my understanding the "CO-value" is the portion of the carbon monoxide in my exhaust.


What do you mean by "leaking gas"?


Volker

 

Keith_M

Jedi Knight

Offline

• Aug 13, 2014

• #7

Volker,
I have no idea what a good value for CO is, but maybe someone else on the forum will know and chime in. I tune my carbs using the "lift the piston a fraction and listen to the rpms" method. And by "leaking gas" I mean quite literally gas dripping from somewhere in the system; float bowl overflowing, gas leaking from the bottom of the jets, loose gas line connections, etc.

Hope this helps. I do think that 12 mpg is low for highway driving. It might get that low for very spirited around town driving.

 

John Turney

Yoda

Silver

Offline

• Aug 13, 2014

• #8

I'm running a Denis Welch DW8 cam, two HD8 SU's, California oxygenated fuel, headers and a lead foot in my 3-liter BN4. Last I measured, I was getting 17 mpg (14 liters/100 km).

By "leaking gas", I think he means liquid fuel is leaking on the ground and not being used by the engine.

 

tahoe healey

Yoda

Offline

• Aug 14, 2014

• #9

Try pulling the plugs after a 5+ miles and check the color. You are looking for a nice tan color. If rich it will be black.

 

DerekJ

Luke Skywalker

Offline

• Aug 14, 2014

• #10

Your fuel consumption equates to about 15 miles per imperial gallon (real gallons). That is high consumption for a BN6 which should be getting about 20mpg at least.

 

J

johnea

Jedi Hopeful

Offline

• Aug 14, 2014

• #11

My BN6 runs about 11-14 liters/100 km. depending on the driving style. Check if the correct carb needles are fitted.

 

AUSMHLY

Obi Wan

Offline

• Aug 14, 2014

• #12

I also had bad mileage. Highway MPG was where it should be. Around town/highway combination was terrible. Seem it was the distributor. Had it rebuilt and mileage increased to what others were getting.

 

Michael Oritt

Yoda

Gold

Offline

• Aug 14, 2014

• #13

I get 23-25 mpg in my 100 Lemans with the larger SU's and a DW "Fast Rallye" cam.

As I recall my ex-wife's stock 3000 gave about 21-23. I sure miss that car.

 

OP

BN6_2197

Jedi Trainee

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• Aug 14, 2014

• #14

John, what are the "correct" carbs needles? I refurbished the cabs two years ago.

 

OP

BN6_2197

Jedi Trainee

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• Aug 14, 2014

• #15

"AUSMHLY", can you explain me the dependecy between the distributor and fuel consumption, please. I cannot imagine any :-(

 

BigGreen

Jedi Warrior

Silver

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• Aug 14, 2014

• #16

.. unwanted resistance and bad voltage ...

 

OP

BN6_2197

Jedi Trainee

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• Aug 14, 2014

• #17

"BigGreen", can unwanted electric resistance and bad voltage really influence fuel consumption? Indeed that could be a good starting point for further analysis. I would really appreciate if you could detail on this. Volker

 

healeyblue

Jedi Warrior

Gold

Offline

• Aug 14, 2014

• #18

Incomplete combustion or incorrect timing can have an effect on fuel mileage. If the distributor is not advancing properly that can effect it.

 

J

johnea

Jedi Hopeful

Offline

• Aug 15, 2014

• #19

The standard needles for a stock BN6 are CV. (Those identification marks are on the upper portion of the needle). Rich needles are marked RD and lean needles SQ.

 

AUSMHLY

Obi Wan

Offline

• Aug 15, 2014

• #20

BN6_2197 said:

"AUSMHLY", can you explain me the dependecy between the distributor and fuel consumption, please. I cannot imagine any :-(

Click to expand...

Sorry, I can't. Maybe someone here can explain it to you.