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.

 

This thread will be moved to the general automotive discussion or fuel delivery forum as it is Not 73/79 specifically related.

ALL user's please read post #9 in this thread.

https://www.ford-trucks.com/forums/s...d.php?t=102632

 

it is on a 1976 F20 hiboy

 

Yes it is.
That isn't the topic.
The topic is "fuel mileage with a certain carb on certain engine"

We're are trying to keep the overload down on this forum.
I have been watching this forum for weeks and I have seen *Actual 73/79 related threads* be pushed to page 2 by threads that are *Not relevant to the 73/79 truck*.
They could be related to a 67-83 truck as well.

 

Moved to proper forum.

To answer your question, your mileage will probably get worse. The 1406 is calibrated for mileage, and as far as I know without looking it up specifically the 1403 is calibrated for performance.

 

yeah, the 1406 is 2% leaner than other 600cfm's.

 

what rods, jets and mmHg springs are you running? What would be best for lean cruising?

 

Due to the weight og the truck and the added drag of the 4x4 components, I'd doubt that you will get much better mileage. You could damage the engine by running it too lean, this will increase cylinder temps!

 

Excuse me, but I am confused; the path that I see for this forum is:
Ê
Ford Truck Enthusiasts Forums > Misc. > Fuel Injection, Carburetion and Fuel System

I do not understand how one can be blamed for not posting 73/79 specific questions. It seems to me that one should use the:
ÊFord Truck Enthusiasts Forums > Older, Classic and Antique Trucks
1973 - 1979 Ford Trucks
forum
for that requirement to be valid.

Not looking for a fight, flames etc. just asking ok?

 

Dunno...i figured guys with my year or closer truck would have some tips for saving a few pennies on gas. The motor is an FE; maybe i should have posted it in the FE forum.

 

The 73-79 is referring to this thread having been moved out of the 73-79 forum.
This thread was moved because the info here isn't specific to those trucks- any carbureted vehicle, whether a truck, car, rock buggy, new, old, foreign, domestic can benefit from this info.

 

I have a 77 F-150, 4x4, 351m, C6, 3.50 gears, 31/10.50s ....

And when I got it it got all of 12 -13 mpg on a good day.

I added a 1850 Holley 600, Performer intake, Crane fireball cam, and mileage stayed the same while it did run better on the road. I know I do not have the best cam in it, but I did this in the late '80s when younger and foolisher.

Along about 1990, I started messing with timing and advance kits and leaning the jets a couple steps (stock Holley is 66 on front, I got down to 62 once) ... and I did see 15 mpg some, saw 16 on one long tank going south on 81 towards Tenn ... then in 91 while frantically working on my house as general contractor in my off time while working my regular "job", when I had little spare time, when I had an empty log shell that needed interior walls, plumbing, electrical, cabinets, flooring, polyurethane, ... when I was busy doing all that and more ... she burnt two valves while under a load of building materials.

I didn't have time to tear her down and have the heads rebuilt ... so I got a set off a junk '79 that I was going to have rebuilt ... and found that the heads had 16 new guides and 16 new valves and so I got real lucky, only losing one afternoon and evening to the swap. I slapped the heads straight on mky truck after my buddy at the machine shop said doing anything to them was a waste of money, and I put 65 primary jets back in the carb and accepted poorer gas mileage ever since. Truck runs perfect ... just like gas at the rate of 12-13 mpg to this day.

Point? ...... Don't get her too lean.