100 miles on the engine but gas mileage is terrible

[nicanor]

I took the RR out for a drive on the freeway to some open space. Up some inclines, down some. The engine stayed within reason with regards to temp. A little higher going up, a little lower going down.

I filled up before I left and when I came back. If I go by the speedo directly, I got about 10 miles to the gallon. But I have 15 inch wheels on the car so I don't know if the gas mileage is a little better because it should be calibrated for a 14 inch wheel.

Still sucks. But it might get a little better once its broken in some.

Seems like the exhaust is knocking against the car/engine/bell housing. Needs knew exhaust anyway, but don't know in what order I'll install new exhaust. Next is the gas tank and cleaning up the under rear of the car.

I'll keep my fingers crossed.
Barry

 

[glhcarl]

My 383 with 64K miles gets 10 mpg in town 13 mpg on highway, with 15" tires and 3:23's.

Back in the day when they sold real gas (100+ octaine) my orginial 383 RR got 13 in town and 16 on highway with 14" tires and 3:23's!

 

[SomeCarGuy]

You went to a bigger than OEM cam, right? That coupled with a rich carb and you could easily lose 4-6 MPG.

 

[nicanor]

I mean, my gigantic Expedition gets 13 around town. I guess I can use it to tow my RR around. :facepalm:

 

[mac]

i guess i can brag that my 440 6 bbl car is getting 15 mpg highway, but it does not get alot of highway miles on it. :drive: :drive: :drive:

 

[ACME A12]

i guess i can brag that my 440 6 bbl car is getting 15 mpg highway, but it does not get alot of highway miles on it. :drive: :drive: :drive:

Mac, I think as long as you maintain your traditional standard of avatar photos/videos you can brag about anything you like and not a one of us will ever complain... :basketcase:

:jester:

 

[69hemibeep]

What, did Mac say something again

 

[roadrunnerh]

Gas mileage? :huh:

Drive her and have fun!!! Screw gas mileage......

Gas mileage is not even a consideration for me when it comes to my Road Runner.
It runs well and that's all I care about.

 

[droptop]

Gas mileage? :huh:

Drive her and have fun!!! Screw gas mileage......

Gas mileage is not even a consideration for me when it comes to my Road Runner.
It runs well and that's all I care about.

x2. It might get alittle better after a few hundred miles. I am sure the engine is tight.

 

[mac]

What, did Mac say something again

 

[droptop]

What, did Mac say something again

:lmao: :lmao: :lmao:

 

[mcmopar]

I took the RR out for a drive on the freeway to some open space. Up some inclines, down some. The engine stayed within reason with regards to temp. A little higher going up, a little lower going down.

I filled up before I left and when I came back. If I go by the speedo directly, I got about 10 miles to the gallon. But I have 15 inch wheels on the car so I don't know if the gas mileage is a little better because it should be calibrated for a 14 inch wheel.

Still sucks. But it might get a little better once its broken in some.

Seems like the exhaust is knocking against the car/engine/bell housing. Needs knew exhaust anyway, but don't know in what order I'll install new exhaust. Next is the gas tank and cleaning up the under rear of the car.

I'll keep my fingers crossed.
Barry

IIRC that cam is a fairly large one and if the engine is new it will be a bit "tight" until it breaks in. Your mileage will definitely suffer until you get it tuned in as well. Mine gets only between 10 and 13.5 on the highway (depending on how fast I want to run) with the XE275HL-10 Comp Cam and it is not as "big" as your cam. I'm running a Holley 750 vacuum secondary carb, Edelbrock Performer RPM intake, tti headers, ported heads, 3" exhaust, 3.55 gears and 275/60R-15 rear tires. It just is what it is. As a general rule of thumb, anytime you beef up performance your mileage is going to suffer somewhat. My next engine may have the Bob Karakashian cam that Mac is running. 15 mpg doesn't sound like a lot but it sure beats the heck out of an average of 11.5!

 

[69hemibeep]

What, did Mac say something again

:basketcase:

 

[Roadcuda]

Wait, I was distracted by that new one from Mac, what where we talking about? Oh yeah gas mileage. Some of you may remember that I was complaining about how bad my mileage was. Well we finally found that it running rich so the jets where changed from 95, to 92, and the metering rods where changed from 59/62, to 59/72. Before this change I was averaging around 9. After a 100 mile trip to a show today it worked out to around 12.75, and that was averaging around 50 mph. So I guess with this crap gas we have now I guess that's where it will be. Don't know if I can get it any better then that, but either way it's a hell of a lot better then what I was getting.

 

[John69RR]

Thats great Mac!! As for mileage my 452 6bbl with 3.23 gears gets 14 on the highway.

 

[V269]

Gas mileage? :huh:

Drive her and have fun!!! Screw gas mileage......

Gas mileage is not even a consideration for me when it comes to my Road Runner.
It runs well and that's all I care about.

Exactly ! What he said. To heck with the gas milage. You built a muscle car and the fuel economy will suffer. Drive the hell out of it and have a blast. The smile on your face will far out way the milage anyday. If you want fuel milage get a Ford Focus. :cents: :cheers:

 

[nicanor]

Did I mention I was from California?

 

[george68hemirr]

GAS MILEAGE???.....I GET 10 MPG WITH A EGG UNDER MY FOOT....off a cliff i get really great mileage.....roadrunners dont get good gas mileage....they were built to run the balls off them....

 

[69hemibeep]

Mine does quite well, in fact its not using any right now :jester:

 

[Roadcuda]

Mine does quite well, in fact its not using any right now :jester:

And I'll bet it's running the quietest it has ever run!!!!