Poor Gas Milage

[money pit]

I have a 360 with auto trans. I'm not sure what rear end gears I have. I have a 4 barrel Edelbrock carb. Is there such a thing as a fuel efficient carb? or should I be looking for higher gears or overdrive to get better gas mileage? I'm planning on changing to a 8 3/4 rear end with 3.23 gears .I currently get 9.5 miles a gallon, mostly freeway driving.  The RPMs are about 2700 at 65 mph.  Thanks

[Chryco Psycho]

Eddys are the least tunable carb you can buy , I have achieved well over double that MPG in 440s & even 512 strokers  .
EFI is the most efficient & the price is comparable to a good carb now ,
My fav carbs are the Proforms , great value & performance tuned properly you can get a significant increase in MPG If you can keep your foot out of the Loud pedal .

[7212Mopar]

I am running a 340 stroker, EFI, 727 auto, 3.23 LSD rear, 25.6" tires. I get average city and freeway about 9-10 mph. 14.5 AF idle, 12.5 to 13.5 AF when accelerating. I get about 12-13 mpg freeway driving average about 75 mph. I don't think a carb can be tuned to get more than EFI.

[HP2]

Ebrocks aren't the greatest to tune, but they can be dialed in a fair amount with step up springs, jets, rods, and shooters.

I've read a few reports that seemed to indicate carbs and efi are actually fairly close in mileage when tuned properly with efi slightly ahead. However, the efi will get there faster and with less effort. Carb tuning is becoming even more of a dark art than it was 30 years ago and getting a carb to this level will require a fair amount of dyno time with a sniffer to get it right. Unless you are replacing the carb, I wouldn't bother with going efi.

Power wise at WOT, it is again fairly close with carbs getting a slight bit more power, but again, requiring a bit more tuning expertise.

IMO, the best way to mileage is maximizing compression, but it requires you build for this from the outset. With an existing engine, maximizing the spark and advance curve along with carb tuning can net increases.  This is most quickly achieved on a dyno with a sensor that can measure tailpipe emissions and provide immediate feedback on changes.  This can be done without a dyno, but will take longer as you make a change and measure the improvement, tweak it some more, measure, etc.

[Huskidrive]

Fuel economy is not always in fuel delivery...........https://moparconnectionmagazine.com/gallery-distributor-recurving-for-improved-fuel-economy/

[Katfish]

Sounds about normal, my situation was pretty much the same.
Went from Edlebrock carb to EFI with really no difference.
Put in a 518 OD and that made the car so much more enjoyable to drive.
Went from 12mpg to 17mpg,  drop in RPMs made all the difference.

[Brads70]

I think its the overall combo not just one " magic bullet " I have a pretty healthy 451 stroker roller cam etc.., Dana 60 with 4:10 gears and a 4L60 OD with a lock up convertor . Quickfuel 850 DP carb and I can get 17-18 MPG on hwy driving just cruising. My old 440/727 with 3:55 was 9-10 MPG's down hill with a tail wind.
I've doubled if not almost tripled my HP and almost doubled my fuel economy. Its the combo. Neil was very helpful when I was picking parts building my engine.   

[dodj]

If you can keep your foot out of the Loud pedal .

I think this is the biggest reason for poor mileage..lol

It's mine anyway. I don't go really fast anymore...I just like to get from zero to a little over the speed limit as fast as possible. If I don't want to drive that way...I take the truck....then I try to do it with the truck...

[money pit]

Thanks everyone for your advice. I'm staying away from EFI because of all the negative info I've gotten doing my research. I think I'll look at the carg situation, the tune, and ignition system. My 360 is basically stock, no headers, exhaust system from TTI.

[Chryco Psycho]

If it is a stock 360 you have a few things working against you , they have low compression & no quench which hurts efficiency , the factory cam is not a great choice either & the manifolds are horribly restrictive .
A well designed high lift cam with a 112 or better yet 114 centerline will help build compression in a low compression engine , Magnum exhaust manifolds will flow a lot better also .
If you really wanted to step up a 408 CI stroker with good heads would be perfect , there really are no good piston choices for the 360 unless you build the 408 , then you would have a very efficient engine  as you could control compression & quench & make a lot more power with less fuel than you are using now .