My 1965 Barracuda was originally equipped with a points & condenser ignition system. After I finished school in 1987, I upgraded my car to an electronic ignition and dual-field charging system from a 1972 Scamp. For a hotter spark, I also replaced the coil with an Accel Super Coil (PN 140001), which probably didn't make any real difference in performance over the OEM canister coil with the Mopar EIS (Electronic Ignition System) at the time.
I really enjoy taking my car for long cruises, travelling around Ontario and beyond. With my daughter now living in Kingston, I regularly drive a 500 mile (800 km) round-trip in a single day so my focus is highway performance and fuel economy. With the completion of the Carter AFB to a Rochester Quadrajet upgrade and carburetor tuning in progress, I found that my fuel economy is better now than it ever was but there is still room for improvement. That means optimizing:
- fuel mixture
- timing advance
Leaner fuel mixtures result in better fuel economy because the fuel mixture has a lower energy density, which requires more throttle. More throttle lowers manifold vacuum which in turn reduces pumping losses. To maximize engine torque, the pressure peak in the combustion chamber must occur at an optimum point after TDC (Top Dead Center), which allows the crankshaft to extract the maximum amount of mechanical work from the products of combustion. Leaner fuel mixtures tend to burn slower, which requires more vacuum advance. Leaner fuel mixtures require more spark energy to ignite, which is the reason that GM introduced the HEI (High Energy Ignition) system in 1974.
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