Would it be worth changing my carb

[badmix]

RIght now ive got a 650-670cfm street avenger. My truck has 305cid w/ 125k, mallory dizzy, heddman headers and true dual exhaust.

The carb is a double pumper I believe, its got dual feed lines. Im just wondering if im wasting more fuel than im using with this carb.

Im thinking of dropping to a single feed 550cfm carb.

But im also going to get a 350 gm crate motor later on, would the 550 be good enuff for that. the motor im lookin at is the 190hp/230tq.

Thanks

 

[Smitty]

The number of feed lines has nothing to do with your fuel usage. That carb should be fine for your engine, but you don't mention if you are having any performance problems with it. If it isn't loading up, bogging out etc., I'd look at spending my money somewhere else. Just my .02....

 

[badmix]

The number of feed lines has nothing to do with your fuel usage. That carb should be fine for your engine, but you don't mention if you are having any performance problems with it. If it isn't loading up, bogging out etc., I'd look at spending my money somewhere else. Just my .02....

The truck runs fine, maybe a tad rich, ive monkeyed with the A/F mix some. My concern was cylinder wall washing (too much fuel getting into cylinder and washing oil off). Also when I fire it up in the morning you can see and smell the fuel. (i guess this is b4 the cat gets warmed up enuff to burn it off)

RIght now I get about 12-14mpg. I figured with a smaller carb id be able to possibly increase that. I dont have a heavy right foot, so I putt around most of the time, but do keep up with traffic. lol.

 

[Smitty]

The Holly carbs are pretty easy to tune. You can always drop the size of the main jets if you think it's dumping too much fuel. I'd pay attention to the float levels if you are smelling gas at start. Also, look for any external leaks.

I don't really care for a Holly on an off-road truck. I'm partial to a Q-Jet if it must have a carb, but that is a whole different can of worms.

 

[badmix]

I know I dont have any leaks. Maybe ill see about changing the main jets. that would help. The floats have been adjusted some when I was bogging going up a steep hill (yea for carbs. lol).

 

[Thunder]

I would try gowing down in size on the main jets.
Also get a secondary spring kit and install a larger spring so the secondaries open a little later. You might pick up a 1 or 2 MPG

If you do want to change carbs. The Holley 470 TA would be an ideal carb for a 305. Would give great gas milage and low end torque. It will also work with similar results on a stock 350 with a little rejetting. A 500 CFM carb is plenty for a stock 350. If gas mileage and torque is what you are after. Most people have a tendency to over carb their engines.

 

[badmix]

cool ill check into that carb. I certainly couldnt make things worse. lol.