I'm not sure how some of y'all accept such low highway mpg from a reasonably stock 383? When our '66 Newport was in its earlier days, we made a trip to deep West TX to see relatives for a holiday weekend. Out past Odessa, Dad said "This thing feels like it wants to run 90", so he eased it up and we "cruised" as I checked out the long distance AM radio reception on that night. This was after we'd filled the tank, so when we filled it up before leaving, the mpg came out to be 15mpg average. Which tended to mirror what "Motor Trend" had with a '62 Newport 361 2bbl road test. That one had the BBD 2bbl, ours had the Stromberg. Later, keeping the speed down to about 70mph, it was more like 17mpg. Just a stock 383 2bbl 2.76/H78-14 deal. With E10, probably would be about 6% lower?
When I was driving the '70 Monaco all the time, I had a friend from college who had a '69 Super Bee with a Holley. 3.23 and G60-14 tires on the back, F70-14 on the front. He said he usually got 15mph on the highway. By comparison, my Monaco 383 "N" 4bbl AVS would do more like 16.5mpg. 3.23/H78-15.
Once, we got the carb on the '66 rebuilt at the local Chrysler dealer (where we bought it with 7100 miles when the new '67s came out). Suddenly, mpg dropped to 11mpg all the time. Why? The "famous" air cleaner air horn warpage, which didn't let any vacuum get to the power mixture piston to keep the power valve closed. So, it was on "full power mixture", about 12.5 to 1 AFR all the time. I made a spacer gasket to fix that problem. Mpg went back to normal. Overall town/highway driving mix we did back then was normally about 14mpg. That's what the cars would do when newer and "gas was gas", even with LEAD in it.
In those earlier days, when we'd get it tuned-up a the Chrysler dealer, they always did the final check with a SUNN Air/Fuel Ratio meter. Once the rpm went past about 2000rpm, in "P", the meter quickly swung the needle to 14.7:1, or "stoich", mixture ratio. At idle, it was usually in the high 12s range. All "normal", for back then.
Considering the availability of wide-band 02 sensors, getting the mixture at cruise can be monitored in real time. Just need to get the sensor installed into the down pipe(s). I know that people seem to like having "rich for power" mixtures for normal driving, but isn't that what the power valve is for? Leaner for cruise, richer as the manifold vacuum drops with more throttle input when more power is needed.
As for the engine sounding "happy", this seems to be easier to do with more cam than what the basic "standard cam" was on the 383s, I believe. This "happiness" can be felt with tight throttle response and ready power with the least throttle input. In one respect, it seemed that after I'd spent hours in the cars, on the open roads of western TX, just me and the car, I could start to understand and "tune in" on these things. Once recognized, it was easy to tell what was going on and when the car was having fun too. These are things that you probably won't notice on a 30 minute commute (and all of the related distractions). Getting these cars out and doing 300+ miles/tank, on open roads in the "country sides" rather than Interstates, you really come to appreciate how Chrysler did their engine tuning, chassis tuning, and designing cars for "The Great American Road". A real "cruise", rather than the 35mph boulevard "cruise" that GM designed for.
Just my experiences,
CBODY67
When I was driving the '70 Monaco all the time, I had a friend from college who had a '69 Super Bee with a Holley. 3.23 and G60-14 tires on the back, F70-14 on the front. He said he usually got 15mph on the highway. By comparison, my Monaco 383 "N" 4bbl AVS would do more like 16.5mpg. 3.23/H78-15.
Once, we got the carb on the '66 rebuilt at the local Chrysler dealer (where we bought it with 7100 miles when the new '67s came out). Suddenly, mpg dropped to 11mpg all the time. Why? The "famous" air cleaner air horn warpage, which didn't let any vacuum get to the power mixture piston to keep the power valve closed. So, it was on "full power mixture", about 12.5 to 1 AFR all the time. I made a spacer gasket to fix that problem. Mpg went back to normal. Overall town/highway driving mix we did back then was normally about 14mpg. That's what the cars would do when newer and "gas was gas", even with LEAD in it.
In those earlier days, when we'd get it tuned-up a the Chrysler dealer, they always did the final check with a SUNN Air/Fuel Ratio meter. Once the rpm went past about 2000rpm, in "P", the meter quickly swung the needle to 14.7:1, or "stoich", mixture ratio. At idle, it was usually in the high 12s range. All "normal", for back then.
Considering the availability of wide-band 02 sensors, getting the mixture at cruise can be monitored in real time. Just need to get the sensor installed into the down pipe(s). I know that people seem to like having "rich for power" mixtures for normal driving, but isn't that what the power valve is for? Leaner for cruise, richer as the manifold vacuum drops with more throttle input when more power is needed.
As for the engine sounding "happy", this seems to be easier to do with more cam than what the basic "standard cam" was on the 383s, I believe. This "happiness" can be felt with tight throttle response and ready power with the least throttle input. In one respect, it seemed that after I'd spent hours in the cars, on the open roads of western TX, just me and the car, I could start to understand and "tune in" on these things. Once recognized, it was easy to tell what was going on and when the car was having fun too. These are things that you probably won't notice on a 30 minute commute (and all of the related distractions). Getting these cars out and doing 300+ miles/tank, on open roads in the "country sides" rather than Interstates, you really come to appreciate how Chrysler did their engine tuning, chassis tuning, and designing cars for "The Great American Road". A real "cruise", rather than the 35mph boulevard "cruise" that GM designed for.
Just my experiences,
CBODY67
