I was wondering what would my mpg be like if i switched to a 390 cfm holley
i have a 1974 gold duster pretty much stock except it has hooker headers, 2.5" exhaust with glasspacks and a clifford intake with a 2bbl on it right now but i dont care for it so i was wondering what the gas millage would be like if i switched to the 390 holley, and how reliable would it be all together because i would like it to be my daily driver its got 73,000 miles and has lived a fairly easy life

Exactly what are you hoping to achieve? What do you mean by "I don't care for it"?

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Too many people who were born on third base actually believe they've hit a triple.

I ran a 390 on my daily for a few years with no big issues.

Kev

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well basicly im looking for a little more power at least more than stock and the 2bbl im having vacuum issues and its too tall for an air cleaner unless i want to make one myself and im just curious on mpg and drive-ability

The best mileage I got with the Hooptie (74 Valiant) was while the engine was stock, running a Feather Duster 2-1/4" and a Holley 390.
The distributor was recurved to work with the four barrel.
I peaked at about 24 mpg freeway. There was a lot of messing about with the 390 to make it work. Pretty much everything had to be adjusted, tweaked, and played with to get it working.
My engine made 8.0:1, which is bare minimum to work. It did not perform as well as most of the 2 bbl cars of like build.

I would seriously think about getting some more compression at a minimum. 9:1 or a tad better will go a long way to making things work better with the 4 bbl. You will want to have a vacuum gauge, a tach, and if possible some form of A/F gauge to tune with. Even if it isn't terribly accurate, you will be able to use it qualitatively if not quantitatively for getting all the circuits working right.

CJ

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Part of Tyrde-Browne Racing

I had a 78 D150 with oversized tires, 3.55 gears, a 4 speed, and isky cam and offy manifold, and I ran a 625 AFB carter on it. it was good for low 20's on the highway, and about 18 if you didn't have to drive in town a bunch, but was point to point running - a country commute.

Decent mileage CAN happen, but it won't happen by accident, usually

I have a aspen that is a street strip car runs in the 14teens it got 16 mpg on the power tour for the week average

Depending on build and rear ratio/tranny/vehicle weight/driving style, you could make OK mileage...

Best with my Hpak motor with the smaller cam was 26 mpg Seattle and back. Last rendition with the Erson 280/270 cam and 3.55's (A-833OD) was about where Ceej was 24mpg (long shot 99% highway Medford to Albany gas station).

-D.idiot

My D100 with the stock 1 bbl and dual cats got about 15 highway and 11-13 city depending on how much of a hurry I was in. Now it has dual Dutra duals, 2 1/4" pipe, and a Holley 350 carb and it seems to get 15 mpg city or highway, and has a ton of power it never had. I'm sure when I jet it down a bit it'll get much better mileage than it does now.

Not really a fan of a 4 bbl on such a small engine, but it's your car, and some others have had great success with it. If you're willing to fiddle around with it, not necessarily a bad thing. Your opinion may vary.

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If it was easy, everybody would be doing it.

My '65 Dart with the Edelbrock 500 AVS and a stout engine with 3.5 gears, 4 speed and 26" rear tires was getting 14.5 in commuter traffic from south Everett to Bellevue down 1-405. This was without the vacuum advance hooked up. It is now getting around 17 mpg with it hooked up.

I have no idea on what it would get on a straight run down the freeway. I do know that I ran from Ocean Shores on the Washington coast to home on less then 3/8 of a tank, and this was with a badly adjusted carburetor.

I do know that an educated right foot gets better gas mileage then the uneducated one.