Gas Mileage

B_man_Al

B_man_Al

Senior Member
Anyone know what the typical gas mileage on a 4 banger is? Since I put an Airtex (2.5-4PSI) pump in with a bypass line to get it down to 1 PSI, my mileage has gone up to around 24 MPG Cdn/ 20 MPG US . Don't ever remember it being better than 20 MPG Cdn. This is an average over 185 miles.

The first fill up was hi test, the second regular. Most of the driving was highway, at between 40 and 45 MPH.
 
If you are getting 20 mpg/US, that's average maybe better than average. I get all around driving average at 17 mpg.
 
The only time I kept accurate records was on a long trip, that time was 23 mpg at 60- 65 over 1000 miles, now it is $ ---miles, 10$ gets me well over 70 miles of parade, local, highway.

I have run my car on a loaded dyne/emission machine to see where settings work , what is too lean, the center plug porcelain tends to be a very light tan if I have the GAV opened, closed it will be white on corn gas ---I feel this is ideal jetting so I can run good with either gas, since model A is not in the emission machine database I had to pick a newer car, entered as a 1990 Honda civic the A would also pass emissions for the standards used for NJ inspection when they used the loaded dyne test when at the very lean side of driveable ----the corn gas does reduce emissions, on a previous test with non corn gas the car could only pass as a 1980 honda
 
My gas mileage has varied dramatically from a low of 13 mph to a high of 21 mpg. I have a heavy Fordor, stock 3.78 rear gears, 5.5 Snyder head, and Mitchell Overdrive. Not surprisingly, my best fuel economy (over 20 mpg) comes from long trips averaging 45-50 mph with Overdrive engaged, over a one-day period. The lowest fuel economy (less than 15 mpg) is from shorter trips around town, where fill-ups are spread out over a week. I assume this is not unusual?
 
Pulled the plugs today. Here's what they look like after 200 mi with new fuel pump. Never been this brown/tan before. Too lean?? They all used to be black before!
 

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Looks good to me. You don't want black, as that's too rich or too cold a plug. Wet and caked black is probably oil burning.
 
This is too lean, lean enough that it is the edge of power loss and not driveable. --it will clean up a black sooty plug, got 2 sets of 3X for free that were black
 

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My car has a .100 over engine, stipe cam, a 7:1 head .. and a F150 4 speed. While doing a tour to Bucks County, PA and back a few months ago, I averaged slightly over 26 mpg. The return trip was on Route 206 at about 60 to 65 mph
 
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