340 gas mileage

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do a compression test. look at spark plugs. a street fuel pump does not need a regulator. with a 235/60-15 tire a 3.2 rear gear and maybe 55 mph would be better-the faster you go the more drag, and wheel alignment and wheel bearings etc. advance cam. and more ignition advance
 
My 1975 Duster 360 is all factory stock. 727 with factory hi stall, 8.25 3.21 suregrip and dual exhaust . Has P225/70/15 tires. At 60 mph it will do 20 mpg to a Canadian gallon. At 70 mph is is down to 16 mpg. Kim
 
what is a canadian gallon ? try 55 mph. my 74 Dart 360 sport 245hp (340) cam 727 3.21 245/60-15 got 16 mpg and ran 14.7 at Epping - tires and advanced timing
 
Canadians use Imperial gallons which are 1.200 US gallons :)

Incidentally, my big-cam big-block's mileage is definitely piss-poor at low speed and lots of throttle stomps, but not as bad as I initially reported... turns out my gauge float is swelling and sticking :rolleyes: I put another 4 gals in the 10 gal fuel cell and it filled it right to the top!

I once had an EFI car that kept getting worse and worse mileage (trip odometer divided by gallons at each fill up). Finally it got so bad that as a previous poster said, "something is wrong". Turns out teeth were falling off the odometer gear inside the speedo head :BangHead:
 
I'd still do one of the basics, check plugs and no I won't get into telling all about my car, how far I've driven it and the gas mileage for comparison sake.:usflag:
 
DrCharles said:
Isn't that what the OP wanted to know? :D
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lol, yeah, I'm sure somewhere he stated he wanted everyones gas mileage. I thought he wanted suggestions to remedy the poor gas mileage, but hey you're a smarter guy than me.
 
I may well be, but in this case it looks like you read the OP's question more carefully.
However... in order to define "poor" we have to know what it is, and it definitely helps to know what everyone else is getting with similar combos (and how they got there). :poke:
 
DrCharles said:
I may well be, but in this case it looks like you read the OP's question more carefully.
However... in order to define "poor" we have to know what it is, and it definitely helps to know what everyone else is getting with similar combos (and how they got there). :poke:
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Well, hmmm, lol, I can't see how any of that helps. He already knows there's a problem and has described it to a T. Pointing him in a reasonable direction of diagnosing will help. How great your car runs has no bearing on his dilemma, but I yield.
 
1406 edelbrock stock was really lean on my mild 318, that carb needs to jet up with a thinner rod set up, also u need to recurve that dizzy if you truely have high compression limit the timing, then lastly limit the vac advance pod stock they usually pull too much timing at cruise, also that cam and those 2.76 not a good combo, try some 3.23s or 2.94s, my 318 mild cammed advanced to 106 9:5 comp gets 15mpg on the street with 3.55s but alot of dizzy work and carb got me there
 
Slantsix64 said:
1406 edelbrock stock was really lean on my mild 318, that carb needs to jet up with a thinner rod set up, also u need to recurve that dizzy if you truely have high compression limit the timing, then lastly limit the vac advance pod stock they usually pull too much timing at cruise, also that cam and those 2.76 not a good combo, try some 3.23s or 2.94s, my 318 mild cammed advanced to 106 9:5 comp gets 15mpg on the street with 3.55s but alot of dizzy work and carb got me there
Click to expand...
 
Um, very sorry. My five year old decided to join the discussion for me while I stepped away... LOL
 
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