Untuned I'm getting about 10mpg city 13highway. I heard from a friend of mine that i might be able to get 17highway with it tuned. This makes me miserable and I'm thinking about using his 224/230.

This 847 has been a beast on the streets but I just can't stand the fuel economy.

 

Get it tunned, that should improve a lot as well as over all driveability.

 

An 847 isn't going t obe great, but its goign to get better than 13mpg definately.

 

I get 15+ and I drive it pretty aggresively. I would think you could get 18 tuned and babying it.

 

With my 6 speed, 4.33s and the 847 cam i could get well over 22mpg on the highway. City was kinda rough though.

 

Could the fact that I have a long-rod 355, dual exhaust, and ported heads have anything to do with the poor fuel efficiency?

 

Heads arn't helping. More air you move through means more fuel also.

 

I can't take it any more. If I could get 25mpg highway with the 847 and my setup, I would keep it. Looks like that's not going to happen. I'll either be going with the stock cam or a 224/230. I do way too much driving for this.

I actually want to sell this car or trade it for a fairly stock car. This car is just too much for my needs.

 

4.10 gears definitely aren't helping the gas milage either, you need 3.42's if you want good Highway miles or something lower than that even 3.23's I tach about 1400 in 6th gear @ 65mph with 3.42s

 

city driving with mine i get about 10mpg and i drive the **** outta the car
dyno tune it and get some more street friendly gears and you should be good to go

 

What the most mileage I could get out of my setup after tuning and all with 4.10 gears?

 

the gears arent going to hurt your mileage that much. its the heads without a tune that's killing it.

 

honestly, one of the big reasons you're getting the mileage you are besides the tune, is the gears...i've seen fully built 409+cid motors get 20mpg with an excellent tune, 6 speed, and highway appropriate gears...

just a question...if you do this much driving, why'd you get the 4.10's in the first place? was this meant to be a more track oriented car?

 

Well, this was before I decided to move to Charlotte from Wilmington. I was going to school in Wilmington and I lived .5 miles away from my job. Now I have to travel 30 miles to get anywhere.

 

well that'll do it... i myself drive to work 45mi one way each day and i can't believe i still wanna get 4.11 gears! maybe 3.42's would be a bit more appropriate for me...or 3.55's or w/e the ratio would be in a 9" (the big mod over winter)