Poor SL-6 Gas Mileage

Sounds like you are not getting a full tank when filling up. Try keeping the nozzle in for a few seconds after it clicks off and put more into it at a slow rate until full. I actually have to hold the nozzle in place on my 64 Valiant otherwise it wants to fall out. Also it is my experience after a fill up that the gauge Stays high and it takes 30-40 miles before it starts dropping. I checked my original 1964 sending unit so I reused it. I've heard too many bad stories about "new" replacement sending units. Sounds like you do not have much history with your new car so it's an unknown for you.

After I completely rebuilt my 225 it seemed to run a little on the hot side but seemed to settle down after break in. After about 100 miles of just buzzin around I reset the lash, adjusted the carb and thinking I probably went with 8-10 degrees of initial timing. I used all new ignition parts recommended by SSD (points) and the NGK long reach plugs.

Almost 2 years and just short of 4000 miles I finally pulled a plug for the first time last week and it looked good. It runs so good i just knew i had no issues. Drove it 320 miles each way to Carliske and got 23.8 MPG from A to B. A being a gas station 1/2 from Interstate here to point B, a gas station right at the Carlisle turnpike exit. 3.23 rear with manual 3 speed.I did run the valves before leaving and only a couple were out.

I'm driving this hulk about 6 hours each way to the /6 race in KY this Friday so I'll change the oil and check the dwell tonight just to be sure.