BBC fuel mileage .... Carb, TBI, MPI, or swap for an LS?

[4WDKC]

I don't have a tach, but that's probably about right. If yours is anything like mine, it chokes the engine when you want it to run hard, yet still runs rich at an idle somehow. It's also extremely sensitive to the quality of the fuel.

Thats your first thing to get fixed, rich at idle is wasting gas an lean everywhere else reduces power.

 

[bucket]

Thats your first thing to get fixed, rich at idle is wasting gas an lean everywhere else reduces power.

Yep, I'll fix it by removing the Eddy carb, lol. I'll put my effort into a Holley instead. I've got a 670 to overhaul for it.

 

[4WDKC]

Yep, I'll fix it by removing the Eddy carb, lol. I'll put my effort into a Holley instead. I've got a 670 to overhaul for it.

Eddys arent bad but must be tuned/setup correctly same as any carb or it'll run like ****. Someone will then swap on a properly tuned carb and it'll be the greatest thing since sliced bread.

 

[74 Shortbed]

All of my calculations say a 500 cfm on a 454 maxes out around 3400 rpm.

Need the 1407 on a 454..

 

[74 Shortbed]

Eddys arent bad but must be tuned/setup correctly same as any carb or it'll run like ****. Someone will then swap on a properly tuned carb and it'll be the greatest thing since sliced bread.

X2...

 

[bucket]

Eddys arent bad but must be tuned/setup correctly same as any carb or it'll run like ****. Someone will then swap on a properly tuned carb and it'll be the greatest thing since sliced bread.

I just like tinkering with a Holley better. I see no point in messing with a carb that's too small, especially since it runs ok as it is. It just could be a little better is all.

 

[4WDKC]

I just like tinkering with a Holley better. I see no point in messing with a carb that's too small, especially since it runs ok as it is. It just could be a little better is all.

Could be the difference between 6 - 8 mp, if its free it could save you gas while you are rebuilding the other, if you have to buy something just wait till the other is done.

 

[Affende]

Need the 1407 on a 454..

Wonder if i could run the 1411, electric choke and 2% leaner for the altitude, then tune it a little more altitude since I need to be about 6% leaner than sea level according to edlebrock.

I have a 750 being built for it by a friend but i dont know the number off of it.

 

[74 Shortbed]

Wonder if i could run the 1411, electric choke and 2% leaner for the altitude, then tune it a little more altitude since I need to be about 6% leaner than sea level according to edlebrock.

I have a 750 being built for it by a friend but i dont know the number off of it.

Yes you can they are the same except for the choke, you can start at 2 stage lean, don't really know what you need until you try it..

 

[Affende]

Wow, yours is choked down with a 500 Eddy too?!

In the recent cold weather, I've been getting around 8 mpg. In the summer I get around 10 out if it. That's with 4.56 gears and 36's, along with driving through a couple very small towns and the rest at 55-60.

There are some differences though. I'm assuming you are running radials where I'm running 6 bias plies. I've also got a th400 and the 454 is fresh.

Does yours try to diesel after you shut it off? about 30% of the time i shut mine off it diesels another round ... especially if i leave it idling for a while.

that says rich to me, or a crack the carb base ... but i honestly know very little and am trying to learn my way through life hahaha.

 

[Affende]

Yes you can they are the same except for the choke, you can start at 2 stage lean, don't really know what you need until you try it..

ok ... it already has an electric choke on it so i think it would be easier to stick with it.

Im really starting to eyeball that GV overdrive unit.

 

[74 Shortbed]

ok ... it already has an electric choke on it so i think it would be easier to stick with it.

Im really starting to eyeball that GV overdrive unit.

I would use it over a manual choke any day... I had a GV in my dually it was awesome with 6 speeds, you'd love it..

 

[Jrgunn5150]

Well the first thing would be to get what you have running right.

Second, it's a big dumb truck. I have a 496 with an Allison OD in my daily, and I get 12 mpg, it's just not going to be good no matter what you do. Driving a Jetta to work everyday will save you more on gas faster than any combination of mods you can do to the truck.

 

[bucket]

Does yours try to diesel after you shut it off? about 30% of the time i shut mine off it diesels another round ... especially if i leave it idling for a while.

that says rich to me, or a crack the carb base ... but i honestly know very little and am trying to learn my way through life hahaha.

It does make the attempt from time to time, it's because I've got the idle turned up a little higher than it should be. That's to combat the occasional tank of poor fuel, which causes it to idle too low.

 

[Affende]

I would use it over a manual choke any day... I had a GV in my dually it was awesome with 6 speeds, you'd love it..

Im thinking it may be the way to go. swap the SM465 for a rebuilt unit and install the GV at the same time, then adjust driveshafts as necessary.

Well the first thing would be to get what you have running right.

Second, it's a big dumb truck. I have a 496 with an Allison OD in my daily, and I get 12 mpg, it's just not going to be good no matter what you do. Driving a Jetta to work everyday will save you more on gas faster than any combination of mods you can do to the truck.

Yeah, I am working on getting it tuned up and running right. I picked up a Subaru Forester for the time being.

It does make the attempt from time to time, it's because I've got the idle turned up a little higher than it should be. That's to combat the occasional tank of poor fuel, which causes it to idle too low.

Perhaps that my problem, I think my low idle is high and my high idle is too low.