Okay so since my 1983 firebird is just terrible on gas I was wondering if getting a bigger gas tank would help at all. I wanna do whatever I can to make it better on gas since it is my daily driver and I know I can't do much since its a 305 v8, I still think getting a bigger gas tank could help. Any suggestions??

 

Would not give you better gas mileage by any means. It would allow you to go longer with the current fuel mileage you are experiencing now. But, this wouldnt be easy. It is designed to fit the factory designed tank, and you would have to do a lot of work to a lot of things, including the exhaust. Side note, your car shouldn't be getting aweful mileage. I consider these cars to be decent on gas unless compared to a hybrid etc. Maybe you have issues with your car running poorly that could effect your mileage in a positive way.

 

As of right now that's hard to say cause I've only had the car a few weeks. I know I need an O2 sensor. I should replace the spark plugs and wires and distributor cap. Mans that's pretty much it unless there's a vacuum leak somewhere eating up gas that's I don't know about

 

How much mpg are you getting approx?

I know on the pedal even a 305 eats it up. Once you get that o2 sensor replaced go back and check. Mine went dead (they don't last long in these cars..) And cut my mpg down maybe 3-6

 

I am not entirely sure how much I get but I'll tell you not a lot man. I have to fill up every few days like it seriously sucks on gas and being a college student working part time I can't afford to throw all my money to gas. So yeah I'll replace both sensors and do the spark plugs distributor and rotor if it'll help out. I still wanna try to do the bigger gas tank though as well

 

Lol I'm in that exact same position. Barely have money for bills let alone when this thing needs a full tank.

Do you have any kind of service history on the car? Even word of mouth of what was supposedly replaced?

 

Yeah I have receipts for over 1000-2000 dollars of what they fixed on the car.

 

make sure the "CCC" electronic carburetor ECM control is working-car will run if this system is disabled,but carb will be stuck at full rich and electronic distributor advance will be limited-resulting in poor fuel economy.

 

My car has been running rich so that is something I'll have to look into actually. But I know for certain the O2 sensor is bad I have the codes that are coming up. I just don't know which sensor is the bad one

 

Spark plugs, plug wires, cap, rotor, O2 Sensor, are the main things you need to swap out along with all of the vacuum lines. IS your idle high?

83 should be getting 22-24mpg in the highway and 14-15 or so in town. That's what my L69 84 got prior to engine swap to 350.

Is your carb "clicking" when you turn the ignition to "run"? It should click for about 30 seconds or so?

 

There is only "one" O2 sensor on the car, in the driver side exhaust manifold, possibly on the y-pipe, but its on the drivers side either way.

 

 

I'm not sure about a clicking noise but I'll check the ecm control definitly.

 

The clicking noise is the Mixture Control Solonid running through it's test cycle. If it doesn't click, and it's loud enough to hear from the drivers seat, then you have a bad MCS and your carb needs to be re-built and a new MCS installed. Without it, the computer can't adjust the part throttle fuel delivery and will run on the default rich "get me home now I'm broke" circuit.

 

Wow I hope it's fine lol how much would it cost to get the carb rebuilt and the mcs put in exactly

 

Rebuild kits run about $40 if you want to try and do it yourself. The MCS won't come with it and runs about $70 by itself in addition to the kit. With that, if you buy it, you're half way to having it one professionally by one of the best.

Otherwise, I recommend sending it off to Cliff Ruggles and have him do it professionally. You won't regret it. He built mine. It's not cheap. I paid $350 to have him rebuild mine and it's run like a champ for the last 7 years. All you'll need to do is put it on the car and do the final tune.