got a 84 with 305 and 4bbl carb. only getting 13 mpg. I rebuilt the carb a year ago. Set it according to the Rochester carb book by Doug Rowe. M/C solenoid is working. What are you getting? Do I need a expert to check the carb out? thanks.

 

My '85 LG4 averaged around 22 mpg and got near 30 on the highway a few times (long trips NOTHING but interstate between off ramps to refuel). That was between 150K miles and the engine swap at 220K miles. I'd expect slightly less for an 84 as it didn't have the knock sensor and improved timing. This time of year your mileage will always drop though. Cold weather choke running eats gas.


Some things you can do that will help:

Make sure your timing is as far advanced as possible without pinging-try adding a couple degrees at a time. Make sure the EGR works properly-it will control light pinging at cruise and allow more timing.

Replace your cap, rotor, plugs and wires if they're not new.

Get a less restrictive air cleaner. Even an open element that may suck in hot underhood air will work better than the factory garden hose. You'll notice a difference.

Loose the clutch fan and install an electric. All of the parts can be had at the JY for next to nothing. I gained near 1 mpg from this immediately in my 85.

Pump those tires up to 32 psi and make sure your bearings aren't worn and your alignment is good.

If you have the $, free up the exhaust. Headers and a cat back will add power and efficiency.

Oh and my daughter's 84 LG4 (all stock) averages near 15 on a good week, but she's NEVER on the highway-just back and forth to school.