Ignition timing for best gas mileage

From : samson

Q: i have an 87 dodge dakota v6 originally equipped with a holley 6280 electronic feedback carburetor. the mixture control solenoid in the carb went south a while back and is no longer available so i replaced the 6280 with a 2280 which is the non-feedback version without the mixture control solenoid. recently after installing the new carb and an msd spark booster and adjusting everything to factory specs i made a 200 mile trip which was about 90% freeway and with a 1/2 mile gain in elevation. i got 22.7 mpg. and this is with a heavy duty lumber rack and a 2x2x4 toolbox full of tools and starting out with a full tank of gas. the truck had about 113000 miles on it. i was really dumbstruck at the gas mileage i got on this trip and then started to wonder how i could better it. the factory manual says disconnect all the ignition timing inputs to the computer to set the spark to 7 degrees btc. thats where it is now. which way should i tweak the timing to get better mileage should i go 5 degrees btc or 9 degrees btc i am especially interested in getting better city mileage with lots of stop and go driving. can i expect this by tweaking the ignition timing -- mccain -- it rhymes with hussein bahrain cocaine insane wolfbane chest pain and chow mein. .

Replies:

From : bob

samson wrote i have an 87 dodge dakota v6 originally equipped with a holley 6280 electronic feedback carburetor. the mixture control solenoid in the carb went south a while back and is no longer available so i replaced the 6280 with a 2280 which is the non-feedback version without the mixture control solenoid. recently after installing the new carb and an msd spark booster and adjusting everything to factory specs i made a 200 mile trip which was about 90% freeway and with a 1/2 mile gain in elevation. i got 22.7 mpg. and this is with a heavy duty lumber rack and a 2x2x4 toolbox full of tools and starting out with a full tank of gas. the truck had about 113000 miles on it. i was really dumbstruck at the gas mileage i got on this trip and then started to wonder how i could better it. the factory manual says disconnect all the ignition timing inputs to the computer to set the spark to 7 degrees btc. thats where it is now. which way should i tweak the timing to get better mileage should i go 5 degrees btc or 9 degrees btc i am especially interested in getting better city mileage with lots of stop and go driving. can i expect this by tweaking the ignition timing -- there are some power - and therefore economy - by maximizing the spark timing. that doesnt always mean setting the most you can get away with that means exactly the proper setting. advance the timing until you get pinging on low grade pump gas. then back of 2*. thats about the best youre going to get without a dyno. -------- ..bob 2006 fxdi hot rod 2008 mustang coupe 2001 dodge dakota qc 5.9/4x4/3.92 1966 mustang coupe - daily driver 1965 ffr cobra - 427w efi damn fast. .