Best possible mileage?

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YY1 said:
I have one friend who, whenever asked, says- "I get *** miles out a of a tank".

While technically part of the equation, it's not the answer, especially since he never volunteers the size of the tank.
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Yep, that's not necessarily mileage but range.
 
AJ/FormS said:
Go Duggie go, you're on the right track!
Get yourself an IR gun and verify your thoughts on the heat thing.
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Thanks for the guidance! When I did the head, mains, and crank seal, I popped the freeze plugs and flushed out sand from the water jacket. Replace the radiator too. The old radiator leaked everywhere. When the 180 deg. thermostat opened, the engine stayed at 180. I used the wife's meat thermometer in the radiator neck to confirm the stat now opens at 195. The needle didn't move on the dash for yesterday's trip but its 40 deg F outside right now.

@YY1, I love reading your stuff man! :thankyou: Without this forum, there is no way this car would look or run as good as it does. A 318 'aint happening man. I've caught the slant sickness. There is something nostalgic, and just plain fun about tinkering on this 6. That warm glow that comes on while driving this antique out of a clover leaf onto the freeway onramp is partly due to how this little motor purrs. :rolleyes:
 
That, sir...is what makes the world go 'round.
 
It is not just the AFR. A host of other factors come into play: car weight, gearing, component parts in the engine that affect cruise efficiency, etc, etc.
Two Pontiacs, one a 455 waggon that is over 4000lb gets 23 mpg on a trip with an 850 TQ; 2.56 axle. Another Ponty, 400 engine, 3.23 axle, about 3700 lb, gets 22mpg with an 850 TQ. These are Imperial gallons, so a bit less for US gallons, but impressive none the less.
 
'64 dart sedan - 225 /6 bored .030 over, headers, 4bbl carb, 3-speed 904. Engine's built for mid-range power. Previous engine had no power once I was trying to go freeway speeds. Could barely get above 65, so worked to fix that.

Averaging 18-20mpg

I do mostly freeway miles around 70mph. I use an app to track mileage at fill up, and how much gas I put in. Then the next time I refuel I put in that mileage and how much gas I put in. It then calculates how much gas was used and how many miles travelled. If I had time and money I'd play around with tunes and driving styles to figure out how to get the fuel efficiency higher but I'll settle for what I've got. That's with a 160º thermostat too, The 180º and 195º just ran too hot for comfort personally. If I had an electric fan that could run full speed at idle, I'd go with one of those, but even with the 160º, if I get stopped in traffic for too long it'll creep up.
 
chinze57 said:
'64 dart sedan - 225 /6 bored .030 over, headers, 4bbl carb, 3-speed 904. Engine's built for mid-range power. Previous engine had no power once I was trying to go freeway speeds. Could barely get above 65, so worked to fix that.

Averaging 18-20mpg

I do mostly freeway miles around 70mph. I use an app to track mileage at fill up, and how much gas I put in. Then the next time I refuel I put in that mileage and how much gas I put in. It then calculates how much gas was used and how many miles travelled. If I had time and money I'd play around with tunes and driving styles to figure out how to get the fuel efficiency higher but I'll settle for what I've got. That's with a 160º thermostat too, The 180º and 195º just ran too hot for comfort personally. If I had an electric fan that could run full speed at idle, I'd go with one of those, but even with the 160º, if I get stopped in traffic for too long it'll creep up.
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That's interesting on engine temp. After repairing everything wrong on the engine and cooling system and keeping it factory spec, once the thermostat opened the engine temp never changed much on any driving condition. The temp gauge is just a graphic without numbers, but the needle is up there when the 195 degree stat opens. The needle hasn't moved hardly at all once the 195 deg stat opens. So far...
 
Duggie said:
That's interesting on engine temp. After repairing everything wrong on the engine and cooling system and keeping it factory spec, once the thermostat opened the engine temp never changed much on any driving condition. The temp gauge is just a graphic without numbers, but the needle is up there when the 195 degree stat opens. The needle hasn't moved hardly at all once the 195 deg stat opens. So far...
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To be clear, I haven’t had an issue with overheating or boil over. With a 180, the needle is real close to the overheating side of the gauge, and we were testing it in summer time. Driving around the city it would creep up slightly at stops and then drop back down to “normal” when I drove around again and the fan was moving.
With the 160, the needle sits just inside of the cool side of up-to-temp on the gauge. Similar situation. When driving, no issue. 3-hours on the interstate and the thermostat didn’t show any warmer than normal. Sit in traffic for 5-10 minutes and it starts getting toasty and temps steadily rise.
I suspect the issue stems from the mechanical fan or lack of shroud. With a shroud I think it would do a better job at idle since it could pull across the entire profile.
 
I think I saw fan shrouds for sale on this forum that were said to fit these early As.

And I've read about people monitoring their AFR to properly tune their cars. Is that really necessary for a street driver that isn't running on the edge of the performance envelope?

Before doing the best cruise timing adjustment for optimum mileage, I mapped out my mechanical and vacuum advance. It doesn't even come close to what they are talking about in this article; Everything you wanted to know about ignition advance | For A Bodies Only Mopar Forum

My Vacuum advance is all in @ 21 degrees at 9.0" of vacuum. And my mechanical reads 2.5 deg @ 1,100 and all in with 16 deg @ 2,500. The receipts that came with the car show a remanufactured distributor was bolted on in 2008, and 5K miles ago.

The good news is we can still drive her about while I tinker on it! :steering:
 
Duggie said:
And I've read about people monitoring their AFR to properly tune their cars. Is that really necessary for a street driver that isn't running on the edge of the performance envelope?
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No.
But the thread title is "best possible mileage?"
Driving on the street sucks gas no matter what because the throttle is constantly jumping around, as you speed up/ slow down/brake/turn/and start up again; and if you make it too lean, it will be even worse.
In town, getting your PowerTiming, and Part-Throttle timing will be much more important.
I think I mighta said this already, but here it comes again;
Every gas burning engine has exactly one crank position that is the best place for peak combustion pressure to occur for maximum energy transfer to the flywheel; which is typically 25 to 28 degrees ATDC. All your timing systems should be engineered by you, to make that happen under as many circumstances as possible, as regards EngineSpeed/(rpm) and Density/(AFR).
 
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In post 24 AJFORMS mentions cruise timing. Would add one step.add load to engine with alterator head
lights high beam, heater fan on high etc. This make effects of adjustments more noticeablle. Otherwise spot-on.
 
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vaccum advance-3.jpeg
 
Saved from some where. Test done by Holley carburetor. on 1975 slant six, 41 degrees at 2200 your dead on it.
 
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Wholey smokes! First trip out today after milling the head 0.100", replacing the Holley 1945 single barrel with a Carter BBD two-barrel carb (+modified single barrel intake) and tube headers. The 2:45 rear end is still there... I also did the AJ/FormS cruise timing, valve adj, thermostat mods. Stock MPG was 18-19. Today, with my foot in it a bit just because it runs sooo much better I got 30! HA! More low-end grunt, sounds great at 3500RPM AND a 50% increase in mileage.
:lol:
 
There ya go! Basic bases covered and it’s all well tuned up and rockin! Congrats!!!!! Enjoy the mileage.

What year and engine size again?
 
AJ/FormS said:
I'm here,lol.
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LMAO! Not you! (The supposedly crazy high MPG guys.)
I still can’t remember the guy, might have been “Mr.Fiberglass” who swore up and down all day that there was a TQ Chrysler used and sold that turned on 45+ miles to the gallon and it was commonly available to the public.

Your mileage claims, once you let loose the knowledge of a double OD trans and a high-ish gear set are more believable though I’ll need to take a cross country trip with you for me to believe your getting better than 32 MPG’s. :poke:
 
rumblefish360 said:
LMAO! Not you! (The supposedly crazy high MPG guys.)
I still can’t remember the guy, might have been “Mr.Fiberglass” who swore up and down all day that there was a TQ Chrysler used and sold that turned on 45+ miles to the gallon and it was commonly available to the public.

Your mileage claims, once you let loose the knowledge of a double OD trans and a high-ish gear set are more believable though I’ll need to take a cross country trip with you for me to believe your getting better than 32 MPG’s. :poke:
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Well those days are over;
that 223/230/110 cam died.
and I did not like the A833od box so it is gathering dust.
And I dropped the Scr a tad last time it was apart.
So 32mpgs point to point are in the distant past.
My latest cam is a 230/237/110,
and Final-Drive gearing is now 2.77 versus 1.97, so
65=2240 versus 65=1600
You'll just have to build your own combo; oh wait! I think you already did, lol..
I used a dedicated Holley 600. When I arrived at my destination, the 750DP went back on.
If I was gonna do it again today, I would start with a spreadbore, and probably a Solid-lifter cam of around 220/108, and pump the pressure up closer to say 190/195/200. And a few years ago I purchased a used Offy Dual-Port, which has been gathering dust..... I'd like to give it a try. With the 3.09 low, I think I could get away with a Final Drive of 2.94 x .78=2.29 , and still lay plenty of rubber with 3.09 x 2.94=9.08 Starter gear.
My car only has one seat in it.... cuz I got tired of cleaning the passenger side of the car...... lol.
 
@AJ/FormS I’ve built a few engines but never a mileage master build. I haven’t even finished sorting out the wife’s engine when, of course, another issue pops up. My sons engine in his ride was a D.O.A. Fresh rebuild. Previous owner left the intake off for a while…. It collected an oil pan full of water. So, I gave up my other engine on the dolly. A 10.5-1, .030-360 for his ‘91 W150 4spd 4x4 W/3.55’s turning stock tires is nothing to write home about on any front really. But it has a Summit cam and a Edelbrock top end & headers. It should be an easy driver. That’s the main idea.

The best mileage I have gotten was 20 mpg’s out a 360. I think I could have done better if I had the funds to try back in the day when I had it. When I first got it, it was insanely low. Best of 10 on the Hwy. OH yea, you read that right. Even with the 2.76 gears.

If I had more cars…. (Like I really need that…)
I have pondered how far I could take a 318-4spd in a Duster on a mileage quest.
 
I think the Barracuda body shape must be pretty good, cuz when I put it in Neutral at 65 mph, it just goes and goes and goes.
I tested it once and I seem to remember that at the end of nearly a mile of coasting, I still had to apply the brakes for a stopsign. I thought that was pretty extraordinary.
 
Great result! Shows what can be achieved with considered parts selection & tuning.

And another example where carb size was increased & efficiency was increased & less fuel used.
 
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