1st off. Did you read...?
65+ Vehicle modifications for better fuel economy - EcoModder.com
And
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
Most of these tips cost nothing, and should be tried first.
2nd. Are you mechanically inclined?
If so, I would recommend two things, a cam swap and transmission swap.
The chevy 250cid 6cyl. is a
good engine. With a cam change it is a
great engine. The cam you want is a torque mileage cam. (some call it a rv or towing cam)
These are two examples;
61-113-4 - High Energy
H- 192/2668- 2S- 12 camshaft - Ch. 194- 250 I6 62- 84
Both of these cams give the engine alot of torque in the lower rpm range.
(what you need for good fuel economy)
The transmission you want is a 200-4r.
Turbo-Hydramatic - Wikipedia, the free encyclopedia
It is a overdrive transmission (30%) with a lock up clutch. It should be a direct replacement for your 3 speed.
The only thing that will be required is a switch to manually engage the lock up clutch since your car lacks a computer to control it.
(if you get one, make sure you get the torque converter with it)
Another choice would be a 700-r4. Although it would require a drive shaft modification.
Both of these mods can be done for less than $500 if you can do the labor yourself and should yield very good results.
Squeezing fuel ecomony out of older cars can be a challenge, but is worth the trouble if you enjoy them.
Hope this helps you.
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