Best timing for a 454?

[Old65C10]

I am getting ready for a trip in my 84 K30 Service truck. It is a 454 with a THM400 and 4WD.
The factory sticker says the timing should be 4 BTDC, but right now it is at 14 BTDC. It seems to run OK and I do not hear any pinging under load. But, I was wanting to set it for the best MPG.
This is a former Fire Truck and it only has 19K miles on it and has excellent service records. It has recent tune up and new wires, air filter, etc.
Should I leave the timing where it is, or change it?
Current mileage is 7 MPG, so anything would be an improvement.

[geezer#99]

Leave the timing where it is, hook up a vacuum gauge you can watch in the interior, drive to maintain as high a vacuum as possible, over inflate your tires (less rolling Resistance), lighten your load as much as possible and put an egg under the gas pedal.

[Dead Parrot]

454 + 4WD rarely equals excellent MPG.

Check the plugs for good color after a drive.

If it has one of the 'pellet' cat converters, replace with a more modern honeycomb type.

Check what RPM your mechanical advance starts to come in and is fully in.

Make sure your vacuum advance is still working.

Make sure the exhaust riser valve, if equipped, is working. A valve stuck closed or mostly closed can cause high back pressure on one side of motor and lead to a ruined carb.

[95 S_Trucker]

The best you will get if everything is perfect is 8-9. You aren't to far from that.

You have a non overdrive transmission. I am going to assume you have 4.10 or 4.56 gears. Those are great for pulling things and hauling loads, but they are bad for mileage.

Even with overdrive, modern fuel injection, and 3.73 gears, my 99 454 gets 9-10.


454s love gas.