WHAT, FUEL MILEAGE???????

[nick cambron]

I HAVE A 91 G/W JUST INSTALLED A JASPER, ENG. ALSO INSTALLED A REBUILT CAR. ALL FACTORY TYPE CARB. CAN'T SEEM TO GET ANY GOOD FUEL MILEAGE. SEEMS TO BE ABOUT 4 - 6 MILES TO THE GAL. ANY THOUGHTS ON WHAT TO LOOK FOR. TRUCK RUNS GREAT. OR IS THIS THE MAX I SHOULD GET.

FACTORY STICKER SAID IT SHOULD GET ABOUT 13?


HELP NO GAS MILEAGE :eek: :eek:

[joe]

Once the motor is solidly broken in you should get in the 13 range providing the rest of your drive train isn't all sloppy/worn out.
Did you tune the rebuilt carb or just slap it on? I'd start there and make "sure" all your vac lines are hooked up right, new etc and look for vac leaks at the carb base etc along with making sure all of the smog/vac junk is plumbed right and working.
A new motor will improve mpg wise as it wears in but you should be getting better than 4-6 mpgs even right out of the box. I'd suspect all the bolt-ons to your new motor is the prob or improper tuning.

[will e]

check the spark plugs. If you are running rich they will be brown and smell like gas. Chilton's manuals have nice colour pictures of what they should and shouldn't look like.

I had a bad carb on my truck. Did better than your mileage but after fixing the carb i get about 13 to 15 mpg.

[Stuka]

actually...black means its running rich...white means its lean, tan means its just right.

But a new engine wont get great gas milage, because there is alot more friction do to everything being broken in. Make you you dont jump on it or anything either, until you are to at least 1000 miles.

[will e]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Stuka:
[QB]actually...black means its running rich
QB]<HR></BLOCKQUOTE>

you are correct. Was tired when I wrote that.

I would think if you are running real rich then you are getting way to much gas into the pistons. This is bad for any motor and probably not good for engines that are breaking in. The gas will get past the rings and make the oil less effective.

[Jeep Craze]

Just kinda verifying the breakin period. I Have a 99 chevy S-10 pickup w/ the 4.3 vortec engine. Bought it brand new. From when I picked it up w/ 58 miles on it till it hit 30,000 miles(yes I typed that right) I got 11 miles to the gallon ( on the highway w/ a brand new 6 cyl. truck) After 30,000 miles around 30,500 miles until now seemed liek over night almoist but the gas milage went from 11MPGH to 18MPGH. Didn't do anything different to teh truck, everything is teh same. Guess for some reason it took that long for the motor to break in. Sorry for rambling....Later Craig

[EEVW]

Nick,

I'll second all thats been said. I also put a 5.9 Jasper in my 88 Grand Wag. Measured the MPG and was getting about 6 mpg.

I was heartbroken. The factory V-8 on 7 cylinders got better than that.

Now over 2 years later I'm around 11-12 in the city, and 13 on the higway at 60 mph.

Give it a while...

Best of luck with the jasper...mine humms especially when I put on the Edelbrock manifold and 4v carb.

Regards
EEVW smile.gif smile.gif smile.gif