The quest for better gas mileage is something that every mechanic is involved in at one time or another. Miles per gallon make an excellent topic with soaring gas prices. In this era of strict traffic enforcement, exploits of how fast your car will go are out of date. With foreign cars and their miserly gas appetites, mileage will provide the more stimulating bar room topic.
The condition of your engine can vitally affect your gas mileage. To tune an engine to its peak efficiency is only half the gas mileage battle. Factors such as car frontal area (bigger cars get poorer mileage than small cars), car weight, body shape and finish affect mileage. The best way to get good mileage is to tune your motor to factory specs and then check out all of the small things we list in this article. Without a good tune-up, attempting to get good gas mileage is like wishing for a 50 beer—it ain't about to happen. A dirty air cleaner can cut mileage by 10%. One misfiring spark plug can cut mileage by 10%. A stuck or inoperative choke can cut mileage by 30%.
After the engine is tuned up, here are some of the tricks used by professional drivers to get more miles per gallon. Open up the spark plug to about .010 more than factory specs. With new plugs and points you should be able to get away with this if you don't demand flatout drag strip acceleration. Use a high octane gasoline and advance your ignition timing to take advantage of the gas. Advance the timing in steps of 2 degrees at a time. Each time you advance the timing, road test the car to see if it starts easily and if it pings. If it pings or knocks the timing should be backed off. A rough way to test if your timing is too far advanced is to drive at about 40 mph on a level road with the engine at operating temperature. Now put the gas pedal to the floor and listen for pinging. If you don't hear any pings you are okay. If you hear any, you had better hack off on the timing unless you want collapsed pistons.
Do not exceed 6 degrees advance over that recommended by the factory as the risk is not worth the mileage improvement. If you are super fastidious and really want to do the job in timing the car for maximum mileage you could rig up a hook up that would let you advance the timing by hand from inside the car. The old Fords had such a device and some motorcycles still have them. What you do in a case like this is to give as much spark advance as the engine will handle at the throttle opening that you are running with. A choke cable can be used to make a setup like this or you can recalibrate yur distributor automatic advance for more mileage. Remember though that maximum mileage and top performance do not go hand in hand. You can't have your cake and eat it too!
Using a higher temperature thermostat will help improve engine efficiency and give better mileage. If your cooling system is in good shape and the pressure cap is working okay. use a 180 to 195 degree thermostat. Another good trick is to use a lightweight oil or a multigrade oil. 10W-30 motor oil is pretty hard to beat for all-around use. 95% of all cars on the road can use this type lubricant with excellent results. By using the lighter oil the engine can warm up more quickly and run with less internal friction. Heavy oil causes a drag on motor parts that wastes power. It would open the eyes of many mechanics if they could see how many dragster drivers use 20W oil in their engines even during the summer. These guys are out for maximum power and minimum friction and they know that a light oil is the way to get it.
A good low back pressure exhaust system will do wonders for mileage. At one time there was a lot of trash written about the good effects of back pressure and why motors needed restrictive exhaust systems. This is simply not so. The only reason for a restrictive exhaust system is that some scrounge at the factory was out to save a few bucks. Dual exhausts with non-restrictive mufflers are the minimum. Even better is a good set of tubular headers. A real bad guy in the exhaust system, like a stuck heat riser valve in one of the exhaust manifolds, can cause a lot of grief. Make sure that the heat riser valve is operating freely. If it's stuck you can try to get it free with a bath of kerosene. Chip off any slag or corrosion that may be holding the heat riser in a stuck position. Graphite is a great lubricant for heat riser valves. Now that we have played the game of gas mileage and got the engine where it will start on a sniff of gas and run all week on a pint of petrol what do we do when we actually drive the car?
No matter how great the engine is tuned and "tricked" into being super efficient, it still has to push around the car. All sorts of things are against your getting the mileage that the car is capable of giving. By not shifting quickly enough you waste gas. If you could be in high gear and instead are in first it costs you 30 to 55% more fuel; in second gear rather then high will cost you 15 to 20% more fuel. Can you think of a better reason to shift?
Underinflated tires will kill mileage. Mileage tricksters often jump tire pressure up to 35 psi cold, This will give you a few more miles per gallon and if your tires are in good shape it won't do any harm to them at all. Dragging brakes that are not adjusted properly will eat up gas. Bad or improperly lubricated wheel bearings cost mileage. If your wheels are out of alignment this will cost you mileage as the car is not rolling straight and is dragging and scuffling the tires. Heavy grease in the transmission or rear end will hurt mileage, especially in cold weather. Highly volatile gasolines that are needed for fast starts in the winter won't give as good mileage as summer gasoline blends. Excessive fuel pump pressure will waste gas. Power equipment such as power steering and air conditioning are gas hogs. Such power equipment must be turned with the engine and this parasite drag uses gasoline. If you were willing to build up gorilla like arms and drive in your underwear you could disconnect the power steering and air conditioning and get better mileage.
A simple thing like idle speed can cause significant changes in gas mileage. The idle should be set as low as Possible without causing the car to stall. Stomping the gas pedal costs mileage as the accelerator pump shoots in gas to give the engine a power boost. Some people will disconnect the accelerator pump to get more mileage. This is okay unless you have an emergency situation where you have to move out. At a point like that you may decide that you would like to have the power back even though it costs you about 14 mile per gallon. Heavy traffic and stop-and-go traffic also eat up gas mileage. Naturally any leaks in the fuel line, carb or fuel pump will give you less mileage since some of the gas won't even make it to the engine. No brand of gasoline will show a significant mileage increase over any other brand of gas. Gasolines vary but the variations are more in respect to climatic and regional conditions than to gas blends.
If the ignition is adjusted properly, higher octane fuels will give more miles per gallon. You can figure that all major brands of premium gasoline have about the same mileage potential. The gasolines are so much alike that only a lab can tell them apart. An extra stop for a traffic light will affect your mileage more than the difference between brands. if you really want mileage get an old light Studebaker six with overdrive. Rebuild the engine using loose clearances and raise the compression, put on tubular headers, recalibrate the spark advance curves, put on small slim tires with 85 psi of air in them, use Vaseline on the wheel bearings, back off the brake adjustments, strip off the chrome, mirror and aerial, remove the fan blade, disconnect the generator, lean out the carb, remove the air cleaner, close all the windows and drive with the wind at your back. If you do this I'm sure that you will trounce any car for mileage. Do you think it's worth the trouble?
The condition of your engine can vitally affect your gas mileage. To tune an engine to its peak efficiency is only half the gas mileage battle. Factors such as car frontal area (bigger cars get poorer mileage than small cars), car weight, body shape and finish affect mileage. The best way to get good mileage is to tune your motor to factory specs and then check out all of the small things we list in this article. Without a good tune-up, attempting to get good gas mileage is like wishing for a 50 beer—it ain't about to happen. A dirty air cleaner can cut mileage by 10%. One misfiring spark plug can cut mileage by 10%. A stuck or inoperative choke can cut mileage by 30%.
After the engine is tuned up, here are some of the tricks used by professional drivers to get more miles per gallon. Open up the spark plug to about .010 more than factory specs. With new plugs and points you should be able to get away with this if you don't demand flatout drag strip acceleration. Use a high octane gasoline and advance your ignition timing to take advantage of the gas. Advance the timing in steps of 2 degrees at a time. Each time you advance the timing, road test the car to see if it starts easily and if it pings. If it pings or knocks the timing should be backed off. A rough way to test if your timing is too far advanced is to drive at about 40 mph on a level road with the engine at operating temperature. Now put the gas pedal to the floor and listen for pinging. If you don't hear any pings you are okay. If you hear any, you had better hack off on the timing unless you want collapsed pistons.
Do not exceed 6 degrees advance over that recommended by the factory as the risk is not worth the mileage improvement. If you are super fastidious and really want to do the job in timing the car for maximum mileage you could rig up a hook up that would let you advance the timing by hand from inside the car. The old Fords had such a device and some motorcycles still have them. What you do in a case like this is to give as much spark advance as the engine will handle at the throttle opening that you are running with. A choke cable can be used to make a setup like this or you can recalibrate yur distributor automatic advance for more mileage. Remember though that maximum mileage and top performance do not go hand in hand. You can't have your cake and eat it too!
Using a higher temperature thermostat will help improve engine efficiency and give better mileage. If your cooling system is in good shape and the pressure cap is working okay. use a 180 to 195 degree thermostat. Another good trick is to use a lightweight oil or a multigrade oil. 10W-30 motor oil is pretty hard to beat for all-around use. 95% of all cars on the road can use this type lubricant with excellent results. By using the lighter oil the engine can warm up more quickly and run with less internal friction. Heavy oil causes a drag on motor parts that wastes power. It would open the eyes of many mechanics if they could see how many dragster drivers use 20W oil in their engines even during the summer. These guys are out for maximum power and minimum friction and they know that a light oil is the way to get it.
A good low back pressure exhaust system will do wonders for mileage. At one time there was a lot of trash written about the good effects of back pressure and why motors needed restrictive exhaust systems. This is simply not so. The only reason for a restrictive exhaust system is that some scrounge at the factory was out to save a few bucks. Dual exhausts with non-restrictive mufflers are the minimum. Even better is a good set of tubular headers. A real bad guy in the exhaust system, like a stuck heat riser valve in one of the exhaust manifolds, can cause a lot of grief. Make sure that the heat riser valve is operating freely. If it's stuck you can try to get it free with a bath of kerosene. Chip off any slag or corrosion that may be holding the heat riser in a stuck position. Graphite is a great lubricant for heat riser valves. Now that we have played the game of gas mileage and got the engine where it will start on a sniff of gas and run all week on a pint of petrol what do we do when we actually drive the car?
No matter how great the engine is tuned and "tricked" into being super efficient, it still has to push around the car. All sorts of things are against your getting the mileage that the car is capable of giving. By not shifting quickly enough you waste gas. If you could be in high gear and instead are in first it costs you 30 to 55% more fuel; in second gear rather then high will cost you 15 to 20% more fuel. Can you think of a better reason to shift?
Underinflated tires will kill mileage. Mileage tricksters often jump tire pressure up to 35 psi cold, This will give you a few more miles per gallon and if your tires are in good shape it won't do any harm to them at all. Dragging brakes that are not adjusted properly will eat up gas. Bad or improperly lubricated wheel bearings cost mileage. If your wheels are out of alignment this will cost you mileage as the car is not rolling straight and is dragging and scuffling the tires. Heavy grease in the transmission or rear end will hurt mileage, especially in cold weather. Highly volatile gasolines that are needed for fast starts in the winter won't give as good mileage as summer gasoline blends. Excessive fuel pump pressure will waste gas. Power equipment such as power steering and air conditioning are gas hogs. Such power equipment must be turned with the engine and this parasite drag uses gasoline. If you were willing to build up gorilla like arms and drive in your underwear you could disconnect the power steering and air conditioning and get better mileage.
A simple thing like idle speed can cause significant changes in gas mileage. The idle should be set as low as Possible without causing the car to stall. Stomping the gas pedal costs mileage as the accelerator pump shoots in gas to give the engine a power boost. Some people will disconnect the accelerator pump to get more mileage. This is okay unless you have an emergency situation where you have to move out. At a point like that you may decide that you would like to have the power back even though it costs you about 14 mile per gallon. Heavy traffic and stop-and-go traffic also eat up gas mileage. Naturally any leaks in the fuel line, carb or fuel pump will give you less mileage since some of the gas won't even make it to the engine. No brand of gasoline will show a significant mileage increase over any other brand of gas. Gasolines vary but the variations are more in respect to climatic and regional conditions than to gas blends.
If the ignition is adjusted properly, higher octane fuels will give more miles per gallon. You can figure that all major brands of premium gasoline have about the same mileage potential. The gasolines are so much alike that only a lab can tell them apart. An extra stop for a traffic light will affect your mileage more than the difference between brands. if you really want mileage get an old light Studebaker six with overdrive. Rebuild the engine using loose clearances and raise the compression, put on tubular headers, recalibrate the spark advance curves, put on small slim tires with 85 psi of air in them, use Vaseline on the wheel bearings, back off the brake adjustments, strip off the chrome, mirror and aerial, remove the fan blade, disconnect the generator, lean out the carb, remove the air cleaner, close all the windows and drive with the wind at your back. If you do this I'm sure that you will trounce any car for mileage. Do you think it's worth the trouble?