wrightm

Hello,
I have a 66 convertible mustang with V8 and 289 engine. I'm pretty sure it is still the original engine. It still runs fine and I would like to rebuild; but the guy I was going to have rebuild it basically told me that if it is running fine then why rebuild....run it till it dies and rebuild it then. Sounded good to me!
But I have had the car from my grandfather for about 15 years now and I think it consistently gets about 11-12 MPG. It has AC but it is disconnected and the engine is pretty much untouched as long as I have had it. With the exception of normal maintenance, a new radiator, detaching smog kit and some other minor things.
Is this MPG normal for this car and engine? If I were to rebuild and try to keep it as stock as possible would I expect this same MPG? I have had many people tell me different stories..that this is normal...and that this is not normal; and it should be getting almost up to 20MPG.
I don't drive it hard and I don't drive all that much or that far. I max it out at about 65 MPH as it gets quite shaky above 70....so it is pretty much just a cruiser.

But just wondering what I should expect to get with a good rebuild.

And along those lines....what would you estimate a good engine rebuild would cost me on this? Just a guideline?
thanks,
M

scottybaccus

I was gonna go right up the middle and say 15-16 mpg, depending on usage, fuel system, gearing and tire size. A 4 barrel carb on small tires with a lower gear is gonna be thirsty, especially around town. Every time you hit the go pedal, you are squirting more gas than the engine likely needs at that moment. Spend all your time on the highway, below 60 mph and you will do much better. Highway at 70+ mph is really gonna suck it down.
You also didn't say where you live. Phoenix will be much different than middle of the Rocky Mountains.

CarGuyZM10

Here in Eastern Pa, we figure we are getting about 18mpg with the convertible (289, 2 barrel carb, original automatic) and 15mpg with the fastback (289, 4 barrel carb, 4 speed). Granted, my Grandfather (who is almost 80) doesn't push them hard...much.

When we take them out, they usually go somewhere around 15-25 miles. Remember that cars usually make better mileage on a longer trip than when you only go a few miles.

GT350R Klone

Yea, that is a low, but not off the charts low and certainly not worth putting thousands of dollars into a new motor.

You might want to check into your carb (choke stuck, running rich?), and make sure the car is in tune; points plug, disti advancing, timed correctly....and my problem, having the right pedal pushed down too much, too often

200ci66

And remember that without the overdrive gear, highway mileage won't make a giant difference in comparison to town mileage. With the 6 banger, I'm getting around 28-29, but with the 289 14-15 mpg sounds about right.

The more engine parts you rebuild/replace the better off you are. Get the ignition right, and get the carb right. Those are your two areas that you should pay special attention to in the fuel economy area. If you're looking to spend the money, a T5 5 Speed will make a HUGE difference.

wrightm

thanks for sharing the experiences with MPG!! Much appreciated!