mileage
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Joined: Apr 2003
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From: Louisville, KY
mileage
How much do you think i would gain in fuel economy by switching from an edelbrock 600cfm (1406) to the 500 cfm (1403) carbs? Right now i get about 8 mpg on my FE 390.
Post Fiend
Joined: Feb 2001
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From: Missouri
Is this 8MPG in the city? Is this stock? What gears do you have? I get 12MPG on the highway with my 390 and 3.70 gears. I have a 770cfm carb.
You may need to change the jets. I doubt going to a 500cfm would change things much and might cost you some power. 600cfm is about perfect for a stock to mild 390.
You may need to change the jets. I doubt going to a 500cfm would change things much and might cost you some power. 600cfm is about perfect for a stock to mild 390.
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From: Louisville, KY
4.10 gears (35" BF's)
crane truck cam with edelbrock heads and edelbrock rpm intake
MSD 6a with pro billet distr.
I was hoping to switch between carbs for driving and for play. Maybe i should try the .095 jets (.098 right now) and different metering rods? Do they make smaller jets for the 1406 carb from edelbrock?
crane truck cam with edelbrock heads and edelbrock rpm intake
MSD 6a with pro billet distr.
I was hoping to switch between carbs for driving and for play. Maybe i should try the .095 jets (.098 right now) and different metering rods? Do they make smaller jets for the 1406 carb from edelbrock?
Post Fiend
Joined: Feb 2001
Posts: 6,624
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From: Missouri
I know nothing about the edel carbs but make sure that you have light advance springs. You could be running very retarded at cruising RPMs. This is where vacuum advance really works well. I got 12MPG without it though. Lean the primaries out until it starts to hesitate at part throttle and then go back up a couple sizes.
While the 35s take more power to push down the road your effective gearing is probably about the same as mine if not better for mileage.
While the 35s take more power to push down the road your effective gearing is probably about the same as mine if not better for mileage.
Post Fiend
Joined: Jun 2002
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From: Atlanta GA
> 4.10 gears (35" BF's)
Have you recalibrated your speedomter or transmission drive gear? If the stock tire was a 31 and you put 35s on it, your speedo is turning much slower then normal.
I have a 2150 2 bbl, beat 390, 31s, and I think 3.54 gears and all I get is 8 mpg, maybe 10 on the highway - hard to tell exactly since I can not fill may tank all the way since it sprung a leak.
Have you recalibrated your speedomter or transmission drive gear? If the stock tire was a 31 and you put 35s on it, your speedo is turning much slower then normal.
I have a 2150 2 bbl, beat 390, 31s, and I think 3.54 gears and all I get is 8 mpg, maybe 10 on the highway - hard to tell exactly since I can not fill may tank all the way since it sprung a leak.
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From: Louisville, KY
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From: Louisville, KY
sorry, what about the springs...5, 6, 7 mmHg (what is stock strength anyway). Which is better for a leaner cruising burn?
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From: Layton UT
390 getting 14 MPG
I just drove my 75 F250 2WD to Sacramento CA from Salt Lake City UT and got 14 MPG at 70-75 MPH. 
I was running empty with the tail gate down. I have done everything I could think of to get better mileage without spending a fortune.
My engine is a rebuild with 45K mi, bored .030 over with an "RV" cam (don't know which one or the specs, my dad had it rebuilt about 10 years ago) NP 435 trans, 3.73 gears and 31" tall 235 85 16 rear tires. The engine is stock with the exception of the cam, Edel 1406 carb and Accel super coil with the plugs gapped at .055". The only other thing I did was I took the belt off of the smog pump (CA truck) and capped the vacumn line to it. I am very pleased with the power and the mileage as it is used mostly for hauling my camper and play toys behind it.
The truck gets a little better mileage now than when it was new. My dad says that it used to get about 12 MPG when new in stock form.
I was running empty with the tail gate down. I have done everything I could think of to get better mileage without spending a fortune. My engine is a rebuild with 45K mi, bored .030 over with an "RV" cam (don't know which one or the specs, my dad had it rebuilt about 10 years ago) NP 435 trans, 3.73 gears and 31" tall 235 85 16 rear tires. The engine is stock with the exception of the cam, Edel 1406 carb and Accel super coil with the plugs gapped at .055". The only other thing I did was I took the belt off of the smog pump (CA truck) and capped the vacumn line to it. I am very pleased with the power and the mileage as it is used mostly for hauling my camper and play toys behind it.
The truck gets a little better mileage now than when it was new. My dad says that it used to get about 12 MPG when new in stock form.
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From: iowa
Originally Posted by chrowen
sorry, what about the springs...5, 6, 7 mmHg (what is stock strength anyway). Which is better for a leaner cruising burn?
I ran the stock stepup springs and rods. I tryed .73 by .42 rods and that night it ran like crap. I don't know because my truck hasn't ran the same since. I currently run a 670 street avenger.
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