AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: WFO386 on April 23, 2011, 05:23:30 PM

Poll
Question: any way to get better gas mileage?
Option 1: 1 votes: 1
Option 2: 2 votes: 0
Title: fuel milage
Post by: WFO386 on April 23, 2011, 05:23:30 PM
i have already put on a bigger air filter and cleaned the carb,I've put a couple bottles of the Lucas carburetor/fuel injector cleaner in (as recommended not the whole bottle that treats 100 gallons) and is removed some carbon from the exhaust but other than that I'm getting maybe 12 mpg  any suggestions or methods that work would be awesome since gas is going up
Title: Re: fuel milage
Post by: thereverendbill on April 23, 2011, 06:57:50 PM
a HEI or TFI upgrade to the distributor will help ya a little on the fuel miliage http://forums.amceaglenest.com/index.php?topic=35398.msg281773#msg281773 (http://forums.amceaglenest.com/index.php?topic=35398.msg281773#msg281773) here is an awesome writeup from member shaggimo on a fairly simple HEI swap
Title: Re: fuel milage
Post by: eaglefreek on April 23, 2011, 07:51:45 PM
If you're running the stock carb you have to make sure all of it's functions are working. The carb is usually the number 1 problem with poor MPG with the carbed vehicle.
Title: Re: fuel milage
Post by: IowaEagle on April 23, 2011, 08:15:57 PM
Keeping the plugs cleaned and replaced as needed is also a help.  Changing the distributor cap every couple of years as well.
Title: Re: fuel milage
Post by: WFO386 on April 25, 2011, 03:54:46 PM
what did the hei mod accomplish?did it make it run at a different temperature or what?i have never messed with a cars wiring b.c. i don't want to mess it up,i read the write up and couldn't make heads or tails of it
Title: Re: fuel milage
Post by: MontanaEagle on April 25, 2011, 04:05:47 PM
I did this upgrade, it's a little simpler than the HEI one

http://www.amceaglenest.com/images/Downloads/MIU.pdf

It's helped me get a mile or two per gallon better and seems to fire a bit quicker.  No new wiring needed really (just spark plugs and 8mm wires), just swapping parts.
Title: Re: fuel milage
Post by: BenM on April 25, 2011, 10:03:15 PM
A wideband O2 sensor kit may help. You'll need to weld a bung into your exhaust and pay for a sensor box, but you can move it between cars if you want.

You'll want to have someone else drive and you can watch the readout, then go to your carb tuning book (I mentioned that too, right?) and modify your carb to be slightly lean at cruise and not too rich at idle or under acceleration. A little trial-and-error later and you have it set!

If you change carbs on your car, it's really the right way to do things. I'm saving up for one myself, and they keep getting cheaper.