8-10 mpg

darth_linux

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Despite upgrading to electronic ignition (HiRev 7500 box and distro kit), rebuilt carb (tuned at idle to 19 in/mg), timing advanced slightly to 15 BTDC @ 500rpm, kick down linkage adjusted to factory spec, etc., I’m not getting better than 8-10 mpg in town even with driving very conservatively.

I’m thinking that’s probably in the ballpark for what it’s gonna get, but I’d love to get up to 12-14 …. 66 383-2V with single exhaust.

Aside from throwing more money at the car in the form of dual exhaust, newer carb, does the collective wisdom have any advice?

I’m buying 91 octane non-ethanol at $4.86 a gallon, and wow, it adds up fast.

Thank you!
 
A$ 7.42 - A$8.64 Per Gallon This Side of the Big Blue Thing.
Don't Know What You're Whinging About. LOL
Yankee Motors Don't Run Anymore Economical Over Here in the Mystical Land of OZ.
My Last 440 Ran About 10 M.P.G.
Latest Beast has a 383 in It.
Have Managed with a Lot of "Jiggling" to obtain around 23 M.P.G. on a Trip.(In Past Times)
When I Finally Hit the Road I'm Hoping to Acheive around Those Figures with a Gear Vendors Unit installed.
Past Experiments Point towards Best Results (Overall) from a 2.92 Final Drive.
Initial will be 3.73 (Can't Take All the Fun Out of Life) LOL
Was Thinking About L.P.G. But The Cost is Now Around 60 % of Fuel
Plus the Loss of 10 - 15 % Economy & Power, Just Not Worth the Effort.
Unfortunately I Hate to Admit It But When They Sort out Decent Batteries
Electric Will be Quicker & More Economical.
Of Course it Will Have None of the Charisma of a 440 at Full Throttle.
And I for One will Sadly Miss the Sound of a Reduction Drive Starter Kicking In!
( Silly Old Fool) LOL
Apologies for the Lack of Any Helpful Comments.
All the Best, Tony.M
 
That’s about par for in town I’d say.
If I were in your shoes, and planned on driving the car often I would “wean” it off of the $5.00 a gallon gas. Your engine should have about 9.2 CR and can run on 87. Is it optimal? No. Will it hurt anything? Yeah, if you let ethanol gas set in your carb for 6 months you could have problems. That’s what I run in my old stuff, every once in a while I dump a quart of 2 cycle oil in a tank just to keep things lubed up.
Do you have hardened valve seats? Your heads were not designed to run on unleaded so dont finicky about fuel now! Lol
Big, heavy cars with big block engines and old slobbering carbs aren’t known for fuel efficiency.
Run the cheap stuff if you want to save money cause the mileage ain’t gonna get much better!
 
Not really much else you can do except maybe optimize the dist curve you might get 1 MPG more. and loose acceleration.
 
Here’s how I look at it. We would all like to get better mileage but the reality is you won’t. If you want good mileage go and buy a new car for 40k plus. Think about how many tanks of fuel that would buy. You would also loose out on the pleasure of owning and driving a truly great car.
 
Despite upgrading to electronic ignition (HiRev 7500 box and distro kit), rebuilt carb (tuned at idle to 19 in/mg), timing advanced slightly to 15 BTDC @ 500rpm, kick down linkage adjusted to factory spec, etc., I’m not getting better than 8-10 mpg in town even with driving very conservatively.

I’m thinking that’s probably in the ballpark for what it’s gonna get, but I’d love to get up to 12-14 …. 66 383-2V with single exhaust.

Aside from throwing more money at the car in the form of dual exhaust, newer carb, does the collective wisdom have any advice?

I’m buying 91 octane non-ethanol at $4.86 a gallon, and wow, it adds up fast.

Thank you!
I have the same engine in my 66. I get 18 MPG (Canadian Gallon). But it is a 3-speed standard.
 
Despite upgrading to electronic ignition (HiRev 7500 box and distro kit), rebuilt carb (tuned at idle to 19 in/mg), timing advanced slightly to 15 BTDC @ 500rpm, kick down linkage adjusted to factory spec, etc., I’m not getting better than 8-10 mpg in town even with driving very conservatively.

I’m thinking that’s probably in the ballpark for what it’s gonna get, but I’d love to get up to 12-14 …. 66 383-2V with single exhaust.

Aside from throwing more money at the car in the form of dual exhaust, newer carb, does the collective wisdom have any advice?

I’m buying 91 octane non-ethanol at $4.86 a gallon, and wow, it adds up fast.

Thank you!
I don't take stock in town driving mileage. What do you get on the highway, like a 50+ mile trip of steady driving on the interstate?
 
I was at a car cruise in Boston a few years ago and was talking to a guy with a early 60's 300. Looked to be a survivor in decent condition. I asked what his plans were for it. He said electronic ignition aftermarket front end with quicker ratio steering and disc brakes all around ,fuel injection ,aftermarket air conditioning and bunch of other stuff.
All I could think of saying to him was "Buy a Toyota Corolla instead. It has all of that" He didn't talk to me much after that.
 
8-10 mpg is very low for your car with a 383 2 bbl. As was mentioned, in post 6, I would suspect your Vacuum advance is dead in the water. My 65 Sport Fury with a 4bbl knocks down 15 avg and weighs in as much as your Newport. I would find an old school mechanic that knows how to tune it and has the testing equipment.
 
Don’t let the car sit and warm up before driving. It just ruins the fuel mileage. A couple minutes is plenty.

Do you have a vacuum advance connected and working?

Do you have 2.76 rear end gears? Of so replace them and get 323 gears. It will help some. Do you jump on a 10 speed bike and start out in 10th gear? Heck now it’s too much work to pedal it at low speeds, takes too much effort. Your engine feels this also.

start by manually downshifting going up hills. Your 727 will stay on 3rd at low speeds. Lots of hills where you live so depending where you are driving you may be on hills most of the time.
 
Here is my take on improving fuel mileage. Something that has not been addressed her is timing chain slack. Worn timing chains are a key contributor to fuel mileage loss. Also worn camshaft lobes can kill engine efficiency. Second, Differential gear ratio does impact fuel mileage. The difference between a 3.23 gear and a 2.76 gear is a substantial and can contribute to poor or better fuel mileage. Along w/ gear ratios tire size is a factor also in overall fuel mileage. Most of our fuselage cars can run a 235r5x15 tire w/ no tire rub. Now to address engine performance. As stated in other posts more initial timing(mine is 12 degrees w/ total advance of 34 degrees total coming in at 2400 rpm. will give you good mileage and throttle response. By following this guideline my fuel mile is 15.2-16.0 miles per gallon.
 
Thanks for all of the replies.

My gear ratio is 2.76:1. My tire size is 215/75R14, which I think is pretty close to what it had originally as far as size goes.

As I noted in my original post, I have a new distributor from Richard E as part of his HiRev 7500 kit. I verified that the vacuum advance, which is new, is functioning when I set the timing with the electronic box. The timing is set to 15 BTDC @ 500 in neutral. The factory setting is 12.5 BTDC @ 500 in neutral, so I have a couple degrees of extra advance.
 
Here is my take on improving fuel mileage. Something that has not been addressed her is timing chain slack. Worn timing chains are a key contributor to fuel mileage loss. Also worn camshaft lobes can kill engine efficiency. Second, Differential gear ratio does impact fuel mileage. The difference between a 3.23 gear and a 2.76 gear is a substantial and can contribute to poor or better fuel mileage. Along w/ gear ratios tire size is a factor also in overall fuel mileage. Most of our fuselage cars can run a 235r5x15 tire w/ no tire rub. Now to address engine performance. As stated in other posts more initial timing(mine is 12 degrees w/ total advance of 34 degrees total coming in at 2400 rpm. will give you good mileage and throttle response. By following this guideline my fuel mile is 15.2-16.0 miles per gallon.
Thanks for the reply. My engine was rebuilt in the last 10 years or so, not sure exactly, but doesn't have all that many miles on it. The car is not driven all that much.
 
Don’t let the car sit and warm up before driving. It just ruins the fuel mileage. A couple minutes is plenty.

Do you have a vacuum advance connected and working?

Do you have 2.76 rear end gears? Of so replace them and get 323 gears. It will help some. Do you jump on a 10 speed bike and start out in 10th gear? Heck now it’s too much work to pedal it at low speeds, takes too much effort. Your engine feels this also.

start by manually downshifting going up hills. Your 727 will stay on 3rd at low speeds. Lots of hills where you live so depending where you are driving you may be on hills most of the time.
subbing the 2.76 for a 2.94 is in the plans. I've heard from several people that 3.23 always felt like it need a 4th gear to shift into when cruising around due to the higher revs.
 
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