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I have an original 64 impala base model with a stock 327 all original. Rochester 4GC carb.
I’m getting 9-10 mpg. I’ve been told that’s about the best I’ll get because it’s just old. It runs, drives, and starts cold just fine. No smoke. Idles nicely. Seems normal and smooth. Drives nice and normal as well. Doesn’t have any punch but it’s just stock. Should I be getting better mpg? What can cause low fuel mileage? And were should I start?
Thanks for any advice.
DN
 

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I have an original 64 impala base model with a stock 327 all original. Rochester 4GC carb.
I’m getting 9-10 mpg. I’ve been told that’s about the best I’ll get because it’s just old. It runs, drives, and starts cold just fine. No smoke. Idles nicely. Seems normal and smooth. Drives nice and normal as well. Doesn’t have any punch but it’s just stock. Should I be getting better mpg? What can cause low fuel mileage? And were should I start?
Thanks for any advice.
DN


Not because it's 'old'. With today's gas, that sounds about right for 'around town'. 'Highway' 14 or so. A 10% ethanol mixture reduces mileage by about 15% (my experience).

My '63 Impala 283 2 bbl (in 1968) used to average about 16 but that was almost 90% 'highway' and gas w/o ethanol. It was a 3 speed manual w/3.36 rear.

Gear ratio and driving 'style' impact mileage too.
 

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Need transmission and rear ratio. The new fuel does make a difference and a good tune up will also. Going from points to MSD ignition should also help fuel mileage. If your running a power glide it is probably one of the least fuel efficient transmissions in these cars and if it even has a minor slip it will affect fuel mileage. Granted I have yet to see a stock power glide that doesn't have a minor slip. If it is a stick shift it could be more about where you are shifting to get whatever giddy-up you can get out of it. 327 likes to produce power at higher RPM where your engine uses more go go juice.
 

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Welcome to the Team!

Mileage depends upon gearing, motor size and air fuel mixture as well as ignition timing.
I think you would be better served with a Rochester QuadraJet (has tiny primaries) more ignition advance if your gas can with stand it without knocking and a tranny change.

Big Dave
 

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63 imp. 283. PG. 321 rear
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Not because it's 'old'. With today's gas, that sounds about right for 'around town'. 'Highway' 14 or so. A 10% ethanol mixture reduces mileage by about 15% (my experience).

My '63 Impala 283 2 bbl (in 1968) used to average about 16 but that was almost 90% 'highway' and gas w/o ethanol. It was a 3 speed manual w/3.36 rear.

Gear ratio and driving 'style' impact mileage too.
Mine is a 63 year the 283 engine in a four barrel quad duel exhaust and you also get about 9 to 11 mph around town. Even with to 321 gear. To speed PG. I would like the two barrel mpg but I prefer the four barrel power top end. An older original little sluggish PG. plan to have tranny rebuilt which will improve performance and Mpg.
 
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