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Price of gas keeps getting higher how do we fight it?Keep yor foot out of it.SCo_hmmthink
That is just no fun !
Yes, well my Mach 1 had not cost me a cent in gas since purchased but then it has been no fun not having it to drive either. Still, I will be trying to improve both performance and economy in the course of time. 351 C, 5 speed, fuel injected - mid 20's? but all the power to play with when the economy windows are down.
Interesting article. But those suggestions are pretty basic and obvious. I'm certainly no expert, but I did a lot of tweaking to improve mileage when a '69 Cougar was my daily driver for twelve years. It had a 351W automatic.

I rebuilt the motor boring it .030 over and installed an Edelbrock Performer cam, Edelbrock Performer intake, Edelbrock carburetor and Mallory Unilite distributor. This worked out to be a great combination for good, low-end torque, driveability and fuel economy. Here are just a few points based on my experience:

- Switching from points to the Mallory ignition made a big difference in performance as well as economy. Consider that even a brand new, perfectly-adjusted set of points start going downhill the instant you start the engine. And a sloppy distributor affects performance and fuel economy. I would highly recommend installing a new or rebuilt distributor if yours is worn. And if your points distributor is already in good shape, those conversion kits which replace points with an electronic module are pretty cool.

- For a street car, I think it's a good idea to run a vacuum advance. This has a HUGE influence on fuel economy. A mechanical distributor may run great on the track, but when you're cruising the interstate at 65MPH, it just won't give you enough ignition advance which won't give you optimum fuel economy. If you already have a vacuum advance, consider replacing it with an adjustable vacuum advance. This will allow you to dial in your own settings. I think it's actually kinda fun to tweak those things.

- If you run an automatic trans, replace and adjust the vacuum modulator. Those things are notorious for leaking. This not only creates a small vacuum leak (again affecting fuel economy), but it can even cause your engine to suck in transmission fluid. (This was happening on my Cougar.) The replacement is easy; and so is the adjustment. Like an adjustable vacuum advance, you just insert a tiny screwdriver into the port where the vacuum hose attaches. Adjust in half-turn increments. Give it a half-turn, then take it for a drive. Keep doing this until you get the shift points to where you want them. While it might seem like shifting at low RPMs would improve fuel economy, I'm not convinced of this. I think it's better to move the shift points up a bit so you're not mashing harder on the throttle trying to accelerate in a higher gear.

- I did a lot of tweaking with the air/fuel mixture on my Edelbrock carb. Since this carb is just a re-badged Carter AFB, I bought a Carter "Strip Kit". As I recall, it wasn't expensive. This kit contains a large assortment of jets and metering rods. Every car is different. There's no way to predict how a carb should be set because it depends on so many variables; altitude, exhaust, cam, cylinder heads, etc. To figure out what you're running, take the size of the primary jets and subtract the size of the metering rods. Then switch out the jets and/or metering rods to lean out the mixture. Keep leaning it out until you experience "surging"; that is, when you're driving at a consistent speed, the engine RMP moves up and down a little even though you're not moving the throttle. Then go back two steps from there for a very good mixture. Of course, you also want to avoid any pre-ignition/pinging, which can damage your engine. But I think a lot of guys get paranoid about this and tend to run a mixture that's too rich. This not only wastes fuel, it can foul your plugs and cause gunk to build up on your valves. You can always keep the secondary jets slightly rich as insurance against pinging at wide open throttle while keep things leaner on the primaries.

Unfortunately, adjusting the mixture on an Autolite or Holley carb isn't nearly as easy as it is on an Edelbrock carb. But the same principle applies: lean it out in small increments until it surges, then go back two steps.

- It never ceases to amaze me when I see a modified big-block with an 800 CFM carburetor and a four-inch air cleaner screwed on top. This can't be optimal. You can find thousands of threads on the 'Net debating the merits of various types of air filter elements. I have personally had good results running K&N reusable filter elements. But whatever you run, it has to be of adequate size. I know it's tempting to install a tiny air cleaner to show off the engine. But if your motor came with a 12" filter from the factory, running a smaller element probably isn't doing it any good and it might be affecting fuel economy. I've heard those Edelbrock air cleaners with the "bump" at the rear actually do make a difference. It might be worth trying.

- Where I live, every gas pump has a "Contains up to 10% ethanol" sticker. I don't care what those ethanol guys say. Gasoline gives you better mileage. Therefore, if you can find a station that pumps 100% gasoline, use it. It will give you the best fuel economy. Where I live, I've been able to figure out which stations tend to pump the most and least ethanol percentages. If I fill up at the my local grocery store station, I get a discount. But, by golly, that gas has must have 10.0000% ethanol because my mileage sucks when I run that gas. On the other hand, I also get a discount at my local Costco station. Costco gasoline gives me great mileage. Thus, I suspect Costco gas has very little ethanol.
Good article Klutch. Do you have any numbers of what you were able to achieve with your Cougar?
(05-05-2011, 01:39 AM)Steven Harris Wrote: [ -> ]Good article Klutch. Do you have any numbers of what you were able to achieve with your Cougar?

Thanks, Steven. Sorry, but I got rid of The Cougar a long time ago and I don't recall the MPG numbers I was getting. I remember being pretty pleased with the end result, but that car did have very stiff rear gears.

Another point I forgot to mention is idle mixture. Most people don't give this a second thought. But I've read tech articles suggesting idle mixture can affect engine performance up to 4,000 RPM. People have accused me of being insane when I suggest this, but based on my experience, I believe it. And if idle mixture can affect engine performance at 4,000 RPM, it can certainly affect fuel economy.

When adjusting the idle mixture on a carb, using a vacuum gauge can be very helpful. (Shoot, those things are cheap and very handy for many things.) Adjust the idle mixture for a smooth idle and maximum vacuum. And make sure the adjustments are exactly the same on both sides. Again, keeping the idle mixture lean will improve fuel economy.

Another point with a lot of misconceptions is engine operating temperature. I used to live in Oklahoma where a typical redneck modification was to remove the thermostat and throw it away. Locals believed it made the engine run cooler which was better. Wrong. It makes the engine run cold which is a big invitation for sludge in the oil, rust on the engine, premature wear of the cylinder bores and very lousy fuel economy.

It's no coincidence that modern cars tend to run at 190 degrees. So, if possible, I think it's best to run a hotter thermostat in a classic car as well. Again, as long it doesn't create pre-ignition/pinging, install 185 degree thermostat; or even higher if you can. Dollars to doughnuts, you'll be surprised how much better the engine runs and you might notice you're using less gas. Of course, the heater will also work a lot better.

Something which can help prevent pinging when running a hotter thermostat is to add an emulsifier to the coolant. Simply put, this stuff "makes water wetter". I've used it in most of my vehicles and it really does work. You can find "Red Line Super Cool" in most auto parts stores. If you want to get fancy, you can pony up some serious cash for the Royal Purple version. Either way, it will improve the efficiency of the coolant which helps to lower the temperature of the combustion chambers which prevents pinging. And, I know it sounds weird, but adding an emulsifier to the coolant also makes the heater work better.

Here's a link for further reading:

I've got a little over 25 mpg out of our 04 Mach 1 on a day trip. It was cool weather so did not need the air conditioning. I would drive it occasionally to work in rush hour traffic including stop and go traffic on I 66 in the Washington DC area and would actually get 20 mpg. This was a 99 mile round trip.
The last car I fuel injected was 25mpg+ This is the way Im going on the 69 also.Plan to do better because I plan on road trips when done.
You take about so many things . But yourselfs . If you are the driver it is how you driver your car . The early machs were built around cheap gas . To sell hot ,fast cars . To so many people if you make any changes from how the cars were made it,s just not the same . Older v8 machs just didn,t get any MPG . Mustang 2s got much better MPG . But weren,t HOT or FAST for a very long time . If any of you plain on driving your cars you need to under stand how all your car works as one . We are going to have too make up our minds get real to survive what is coming at us faster than we will ever know . Change is very hard for all of us . Take a stand make yourself,s be heard . I beleave in the power of numbers to fight back . GAS and so on . If things change just don,t go back to the old ways or we all have lost our way of life that means so much more . I know first hand many times over . Please learn from our past mistakes . Because this isn,t over yet . C . L . The hole world can fall . USA
I filled up my 73 Mustang convertible today, which is a 250 CID 6 cylinder, and I'm got 11.1 MPG!!!!! Of course that is all short trips around town. I have always kept a trip diary in the car and even back in the 70's the best MPG I every got was just over 18 MPG! Probably your 302's and 351's get just as good if not better.
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