My 340 getting 6 mpg

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64whiteghost

64whiteghost

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Whata up guys !

A little update on the 64whiteghost aka my 1964 plymouth valiant.

Got my 340 running and broken in i havs about 150 miles left to hit the 500 miles. But i have one problem. Im getting 6 mpg

Im running an FST double pumper 750 with 67 jets. Idk what power valve yet. But im assuming it has the stock 6.5.

Motor: 340 .30 over

Cam specs: See photo. It is a custom cam and peak power is at 680p rpm

Cylinder heads: flow bench showed 235cfm

Rear: 8 3/4 3:73s with a posi

Im wondering if my 750 is too much. Power is crazy good and im happy with that. But my mpg is insane lol And im wondering if i need to go down to a 650 and if that would help.

Thoughts?



In wondering

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What rear end gears are you running? If you are turning 3500 - 4000 rpm to maintain 65mph, theres your answer.
 
Double pumper, 4 gear, I see your having fun. Need more info if you want better mpg.

You're smiling in the picture was that before or after you filled the tank with CA pricing.
 
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Mopar64340 said:
Whata up guys !

A little update on the 64whiteghost aka my 1964 plymouth valiant.

Got my 340 running and broken in i havs about 150 miles left to hit the 500 miles. But i have one problem. Im getting 6 mpg

Im running an FST double pumper 750 with 67 jets. Idk what power valve yet. But im assuming it has the stock 6.5.

Motor: 340 .30 over

Cam specs: See photo. It is a custom cam and peak power is at 680p rpm

Cylinder heads: flow bench showed 235cfm

Im wondering if my 750 is too much. Power is crazy good and im happy with that. But my mpg is insane lol And im wondering if i need to go down to a 650 and if that would help.

Thoughts?



In wondering

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DentalDart said:
6mpg sounds like a good time. :thumbsup:
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Smiles per gallon, but it seems pretty excessive.
 
I drove 75 miles last Sunday and used 1/2 tank.

273 2bbl 3.23 gears 215 70 14 tires

3/4 of it was on the interstate at 75 mph
1/4 was on surface

Just over 9 mpg
 
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Little too much cam and little to deep rear gears. Carb not tuned in for mileage in mind.

Other than that, no funny noises > then all is good.


☆☆☆☆☆
 
Yes pulling a spark plug to see if it is burning rich.

Do your eyes water when standing at the back of the car with it running at a fast idle?


☆☆☆☆☆
 
Smaller carb doesn't equal less air and fuel it's just more restrictive.
 
moparlvr166 said:
Double pumper, 4 gear, I see your having fun. Need more info if you want better mpg.

You're smiling in the picture was that before or after you filled the tank with CA pricing.
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I smile even though shes is a gas guzzler. The car is amazing and i love it. But just seeing what other guys have done to get better MPG with a high horsepower motor like mine
 
Mopar64340 said:
8 3/4 3:73s. What other info you need ?
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I personally think you should pull your plugs and see what they look like? Is your carb tuned properly?What is your driving style?

I don’t have a manual… but when driving I may or may not leave my car in gear longer than I should to hear the noises it makes, especially when I pass parks, cars, houses, or people mowing their lawn :lol: then about every 5 minutes or so, when it starts getting warm, I decide that I need to clean the carb out and get some fresh air in the car… , so I stomp on the gas.
 
Its is semi tuned correctly. But yes. Im looking into finding a shop that can dyno tune it correctly
 
Learn how to tune the carb and if you’re not running ported vacuum advance with around 45-48 degrees of cruise timing you should be.
 
TT5.9mag said:
Learn how to tune the carb and if you’re not running ported vacuum advance with around 45-48 degrees of cruise timing you should be.
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My timing is 10 initial and 34 advanced. I ordered a 4.5 power valve and im going to see what mpg i can get this saturday
 
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