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Gas Mileage

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Griz

Griz

Jedi Hopeful
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So, I've just finished the restoration of my BJ7 and have been driving it quite a bit this summer trying to get some miles on it close to home so I can correct any issues that pop up. So far so good, not many issues at all, except that it seems to be guzzling gas. I know it's running a little rich, but not so much that you can see any exhaust. I'm getting about 10 mpg around town and only about 13 mpg on the open road. What should I expect for gas mileage?

Griz
 
I drive my BN7 100-200 miles a year, 10 or 15 miles at a time and get about 12 mpg. The car runs great, I checked it with the glass plug device (Gunson?) and the flame looks good, but there is some black soot collecting on the rear bumper above the exhaust. So it’s probably rich, but with my very limited mileage, I don’t worry about it.
 
I've driven my BJ8 140K miles over 33 or so years, and put 5-6k miles a year on it. I've consistently gotten:

- 15mpg city
- 18mpg fast highway (70mph+)
- 20mpg medium highway (60-70mph)
- 24mpg slow highway (55-60mph)

Note these figures are calculated during long road trips, with myself and an adult male passenger, and a hundred-fifty pounds or more of baggage, parts and tools, etc. and spare tire. It didn't change any after a recent overhaul, before which I had one 'dead' cylinder (60psi compression). Go figure. I also didn't see a significant difference between 'pure' gas and 10% ethanol (though I usually don't let the tank go below 1/4, so there's some mixing).
 
Nice one John.

But I guess that I am getting about the same as Bob S, maybe a bit less around town. There again I have a heavy right foot and a very strong brake spring.:thankyousign:

Not sure about the slow and medium bit - the words do not enter into my vocabulary :highly_amused: I like the throaty roar on an open road and if the truth be known I'm not sure what the words speed limit mean:angel2: but I do tend to drive safely.

:cheers:

Bob
 
My 100's mileage varies between 19 mpg or so "around town" (there really is no "town" here in SoMd) to 23-24 on the highway at slightly higher than legal speeds.
 
re: "Not sure about the slow and medium bit - the words do not enter into my vocabulary"

I always drive at the fastest speed I think I can get away with; however, when you're stuck in traffic there isn't much choice, and I try to avoid speeding tickets, especially out-of-state (several US states are known for speed traps; and in Canada they tow your car if your really push it). On another note, I've been pulled over four times in my BJ8; once by a local cop near Bakersfield, with my young son in the car, due to rubbernecking the view and not paying attention to the speedo, once hot-dogging it on a windy mountain road in Wyoming, once when I failed to decelerate quickly enough in a construction zone in Wyoming--fines are doubled--and once when I passed a California Highway Patrolman who I thought was doing 50 in a 55 zone (turns out my speedometer hadn't been properly calibrated after modification for taller rear-end gears). All four times I got a pass--even though I was so rattled I tried to hand the CHP my American Express card instead of my driver's license--and I got a written warning in Bakersfield. But I don't want to push my luck.

A few times I think I've gotten 25mpg, but I think it's more due to cavitation in the tank causing optimistic pump readouts.

Side note: I thought I'd get a little better mileage when I installed a Lempert 3.54 rear-end gear set, but didn't notice a difference. I think it's because although the engine runs at a slower RPM for any given speed, it has to work harder to overcome the greater load.
 
Those numbers are low, but I don't think scary low.

For the first 5000 miles after rebuild, I was getting consistently 14 MPG in mixed (but mostly 2 lane country road) driving in my BT7.

After that - with more miles on the engine, carb floats that don't stick, a gas line that no longer seeps at the tank fitting, and some general timing and carb adjustment fiddling - I'm seeing 18 MPG.
 
Good tail there Bob S,

I do recall that I had great mileage in the early days of ownership, but no top end speed, I mean above 60, then I unblocked one of the carbs, the HS6 has a stuffing gland connection into the float chamber and the rubber seal had collapsed around the end of the pipe. Things really started to go down hill after I fixed that :highly_amused:, I mean really down hill, the top end speed went up, the fuel consumption went along with it and to top it off, the previous lean mixture hastened the burning out of one of the exhaust valves.

:cheers:

Bob
 
With 119,000 miles on my BJ8 over 34 years, my experience has been similar to Bob Spidell's. Most of that mileage has been on long trips and I haven't really bothered to check local gas mileage. I tend not to push the speed too much over the limit, but I did get a warning once from a cop in Council Grove, Kansas when I was roaring through his town at 29 in a 20 mph zone, in a hurry to get to Open Roads at Lake Tahoe. He was impressed with the Healey enough to let me take his photo.
The best I've ever gotten has been 22-23 mpg.
 

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Hi All,

I use High Octane fuel since the car was new and over the 54 years have commonly achieved around 14 MPH and occasionally, for no identified reason, gotten as high as 17 MPH. On one occasion, driving from SE Penn to NE Penn to NYC and back to SE Penn I achieved a high of 54 MPG with little side effects. Since the trip was mostly on major highway, starts and stops were very limited. I did have problems getting up to speed but at those times initially attributed it to the mid-winter cold snap.

When finally arriving back at SE Penn (home at the time), I discovered the problem after about a week of looking. The needle of one of the carbs had gotten loose and would fall to block off fuel to 3 of the cylinders (thereby running on only 3 cylinders). However, this blockage was not constant as when the piston fell, the pin sometimes caught and was lifted to bring the rested pistons back to action. Since the Healey could easily cruise at 75 MPH on 3 cylinders and 1 carb, I toyed with the thought of finding a way to use an electromagnet to make this a controlled function of my Healey but never followed though.

Ray(64BJ8P1)
 
Ray--

Bad idea: Unburned fuel will wash the oil off of the cylinder walls and rings and cause engine wear. Also it will dilute the lube oil.
 
Hi Michael,

Yes, I agree and will not be implementing the controled 3-cylinder shutoff/turn-on. It was at least 50 years ago when this took place and has not been done yet.

Ray(64BJ8P1)
 
23 Uk gallons on welsh roads on average cruising between 50 to 60 on a 60k engine that’s had one previous rebuild. Which I don’t think is bad as it equates to about 27.5 US
 
The UK gallon is bigger than ours: One imperial gallon is equivalent to approximately 1.2 U.S. liquid gallons.

If 4tecdog is getting 23 miles on a UK gallon he would only be getting about 19 miles out of our gallon which seems about average.
 
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