How can I get more MPGs ?!?!?

6

65beauty

New member
I'm getting about 15mpg (combined city/hwy) on a 65 Mustang Convertible 6 cyl 200 CID Automatic all stock.

I just rebuilt the carb; new plugs/points/condenser/hi-perf coil/new airfilter/new fuel filter, new inline-glass fuel filter. Head redone. Autolite plugs are gapped to 0.032, timing to spec. New tires stock radials 185/70 14, new exhaust.

Which upgrades will provide the best increase in Miles per gallon? Is 15 mpg (combined) normal?

Thanks!
 
and consider the 2bbl upgrade....you can find details all over here on upgrading to a 2 barrel with progressive butterflies (is that right?)
 
You have to be careful when doing upgrades in search of miles per gallon.

Even as expensive as gas is, spending 300$ on a header to get a 2 mpg gallon increase, it will take a LONG time to recoup that 300$.

Especially in a non daily driver situation like most of us have with these cars.

So, if your sole purpose is to try to increase mileage, you really need to think about it.


However, more often than not, an upgrade that improves mileage will also improve power as well as overall drive ability, so it has other intrinsic value.


It's up to you to determine what's important.
 
I have to say a free flowing exhaust cost me some major MPG I ended up going back to a quality truck sized muffler and pipe only a half inch larger than stock. And I have a stock manifold. gained a few more Hiway MPG and total performance I think I read this same thing in a old Ford bulletin.

the back pressure is important in daily driving to a extent.
the Cherry Bomb and large exhaust was gutless unless your pulling some higher RPMs.

I tend to set the timing a little faster than stock, about 2 more degrees.

I have used a stock replacement K&N for years but I dont think it helped at all...

but Dollar per dollar the DSII is a great swap letting that Hi Performance coil do its job. Also you get more gap at the plugs... I get a cleaner burn for sure.


Frank
 
Howdy gary and All:

Yes, 15 MPG all-around is about typical. When you say that the head was done, what did that include? Was the head milled to compensate for a new thicker head gasket?

Here is a list of free or inexpensive things you can do to increase your mileage.

*Air up you tires to the Max psi lettered on the sidewalls plus another 10%. 32psi plus 10%=35. Check them at least monthly. Radials help! Good move.
*lighten the load. Don't carry anything around with you unless you need it.
*Don't overfill your gas tank. Expansion and vaporation, even in a closed system, loses gas.
*Advance your ignition about 5 degrees beyond the stock setting. IIRC your's specifies 12 degrees BTC. Try 15 or 16 degree. Listen for ping. IF you get any reduce initial by 2 degrees and try again.
*Regap your new plugs to .035".
*Make sure your idle and choke are set as lean as possible. Use the leanest setting for the accelerator pump on your carb.

The biggest difference will come from how you drive-
*Avoid unnecessary cold starts. Do not idle on start up. Start up, put it in gear and drive off. Your engine will warm up faster and more efficiently while driving. An engine up to operating temp is more efficient than a cold engine.
*Coast more. Plan ahead. Slow down.
*Drive as if you had a raw egg under the accelerator pedal- and you have to clean up the mess if you break it.

An upgrade to a more efficient ignition such as the Petronix Ignitor in your otherwise stock system is a good move. At about $60.00 it is NOT cost efficent for improved mileage by itself. But the combo of quicker starts, smoother idle, improved performance, fewer tune-ups and increased mileage makes it worth the money.

A DuraSpark II upgrade will not be compatible with your stock carb.

Keep us posted on your progress.

Adios, David
 
David -

A DSII upgrade cares not what carb is on the car. All that matters is that you use a manifold vacuum source for the distributor, which can be gotten many ways.

Just because the stock carb has a SCV valve and it's related vac port, doesn't mean that HAVE to use it.
 
almost same setup but I have a pertronix II and am getting 22mpg as a daily driver,,, I also have a 3 spd manual tranny,, it took some playing around to get to 24 mpg before I got my head rebuilt and am dialing it in slowly but surely to get back there
 
David, Ian and the many others who replied. Thanks a great deal for your advice. I'm certain it help me enjoy my "new" mustang. I did order the Falcon Perf. handbook.

Thanks again! :D
 
8) gary, to a certain extent, adding power will improve fuel economy, IF the parts selection is correct. too much cam wastes fuel as much fuel as not enough cam does. too much carb capacity can hurt fuel economy as much as not enough carb capacity. same with the exhaust. the external stuff, like a better ignition, a bit more carb with staged secondaries, a freer flowing exhaust, all help, but you are looking at small gains here and there. to get the larger gains, you will need to get into the engine, and that is best done when rebuild time comes so you are not spending money excessively. gearing, synthetic fluids, brake shoe adjustment, front end alignment all affect fuel economy as well. when rebuild time comes, take a complete systems approach to improve both power and mileage.
 
Some food for thought here guys.

Don't believe that softer driving is going to save you mpg's. If you start accelerating quickly, I mean really put your foot in it, then your engine gets up to an rpm that it burns gas more efficiently at. I did an experiment, I had several people drive normally, mildly and aggressively, my results weren't conclusive because not enough people volunteered, but the results I got showed that people got their worst gas mileage at mild driving, there middle mpg at normal driving, and their best mpg at aggressive.

The moral of the story?

Accelerate quickly, coast to a stop, and get a blanket for that egg of yours.

As for my mpg - 22 Highway (It is probably better as a daily driver considering that there were 3 of us, our luggage, and enough tools to rebuild the engine.

60 falcon
200 I6
- Head -
Ported
3 angle valve
Milled .080
CR comes to about 9.5

- Lower End -
280* cam
rhoads lifters, brings idle *s to about 173
Bored .030 over
Pretty much stock everything else

- Spark -
Stock distributor (had petronix - great system)
Hot coil, 40,000v
Alternator - Great upgrade, as soon as it turns over the GEN light goes off

- Gas -
Weber 38/38 DGEV

- Running Gear -
C4 tranny
Stock 60 rear end (3.80 ratio I think)
Pizza cutter 13's
 
Howdy back Gary and All:

Ian- Don't get me wrong. I love the DS II and am using a junkyard rescue with a re-curved centrifugal, but there is no way a DS II with a manifold vacuum source will work as designed. Can it be done, "YES", I've done it! Is it perfect? No!!!!

The DS II is designed to work with a ported vacuum source, not full vacuum. That's the difference.

Sorry to be so blunt.

Adios, David
 
I agree.

I've been doing experiments with my wife's Envoy, which has an instant MPG readout. The more time you spend under about 35 mph, the more fuel you burn whether you are accelerating hard or not. 4 mpg for 8 seconds is better than 8 mpg for 20 seconds. Also, the fuel economy stays under 20 when under 35 mph even when at a steady speed. The best economy is had from 55-60 mph (at least on that vehicle), where I get from 25-30 at a constant speed.

I know it's not exactly the same, but the same principles should hold true.
 
You can recurve the DSII to run off any Vac source you like.

The only real difference between Ported and Manifold is at idle.

Running off manifold will give you more advance at idle, which is a good thing.

As soon as you crack the throttle appreciably, ported = manifold for all practical purposes. There was even someone on this list who hooked up a pair of vacuum gauges to prove the point.

Besides, if you really need a ported Vac source, thats easy enough to come by.
 
The accelerating quickly is great if you can stay out of the enrichment circuit.

My camaro would pull 25 mpg if I baby it. Dip in, and you can literally watch the gauge drop.

My honda is the same way. I can get anywhere from 25-30 mpg per tank depending entirely on how I drive it.
 
HOwdy Back All:

We're drifting off of Gary's original query in this post. While all of this is interesting, I took Gary to mean he is looking for "simple, cost effective, bolt-on upgrades to achieve better MPG". That's what I offered. Does anybody have any other ideas for him?

Wallaka's post brought to mind cruise control. My father-in-law and I had a debate on the most efficient way to accelerate his motorhome. He took forever to gain cruise speed. I would just punch the "Resume" on the cruise control. It turns out the the computer controlled cruise control system is designed to optimize acceleration to regain cruise speed.

Bort brought to mind another "Oh ya". With a carburator, everytime the accelerator pedal is pressed a squirt of raw gas is delivered. For ultimate mileage, one could unhook the accelerator pump. You'd also have to learn to accelerate slooooowly.

Adios, David
 
Thanks David, Ian and all for your help. I'm going in stages trying to achieve better MPGs. After all the obvious stuff (making sure all stock is working up to par), i'm thinking about the Pertronix I, with the hi-perf coil and regapping to 0.050.

Do you think this will make a noticeable difference in MPGs? How much of a difference in MPGs do you think this might give?

Thanks!
 
Best mpg I have been able to get so far is just over 27.5 mpg.
That was over about a 100 mile highway stretch, at between 3k to 3600rpm, 70 to 85 mph.
Tailgating a speeding semi in a headwind part of the way. :p
It's so hard to account for the gas wasted during starting, idling, accelerating, decelerating, braking, resuming, any kind of city driving. Pointless to me to even try to evaluate what kind of mileage you get in town. Too many variables.
I also put Lucas upper cylinder lubricant in my gas. ;) I think a clean head would improve mileage.
Stock 1946 carb with all emissions removed except for EGR. Cam advanced 4* and a recurved DS2. I too run around 15mpg or better in city, FWIW, doesn't matter how I drive, but I'm usually bootin' it.
I just got a red grommet DS2 and will see what, if anything, that does.
I've been curious as to the use of the two port distributors.
Wasn't the other port just to provide the right vacuum for deceleration, when you take your foot off the pedal? Lotsa gas wasted when you take your foot off of it. Sometimes I shift into neutral (C4) so the engine goes right to idle for a long coast off high speed.
 
Howdy Back Gary and All:

To be somewhat emperically accurate in assessing changes in MPG, you will need to establish a base line over a time and distance that is repeatable. Once you have that base line, you can make a change and reassess.

In addition to your planned upgrades be sure to optimize your initial advance setting.

The Ignitor will also improve idle quality, be sure to reset the idle after installing the Ignitor and increasing initial advance.

A 5 to 10 % increase in mileage will take you from 15 mpg average to 16.2 to 17mpg average. Depending on many variables. Given your planned upgrades 5 -10% increase is within the realm of possibilities. I sure hope you post your results back here for the benefit of others.

Adios, David
 
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