Stu your running non stock tires so your odometer will be off slightly. With the 205/60 R13 Sumis your running the tire is about .5" smaller. This will translate into a 2% difference in the odometer. So I would say you saw 31*.98 = 30 mpg. Just to be accurate. Still great BTW.

 

larger bore? it's a square bore carb, primaries and secondaries r the same size. he's running quite abit leaner on the stock port than what i am on streetport. i might can squeeze low 20s on the highway.

 

I had talked to Kentetsu about this same thing when i took a 200 mile round trip to my cabin i was getting around 33 MPG as well but he said no way.

I have filled my car with 10 gallons a time for 3 weeks now and ran it to empty sputter mode and in the city i get about 27 MPG.

Heres the kicker i took that same trip again and only put 2 gallons of gas in.
Get this 85 miles all highway and rolled to a stop 5 miles from my exit.

75mph at 3,800rpm

I was astonished.... Kentetsu said no way but i did what he told me to do and boom big time travel saviings

 

This doesn't make sense to me. Are you saying you used up exactly 10 gallons each time you filled up? Or did you just add 10 gallons to whatever was already there? Either way sounds like your not doing the measurements correctly.

The way you measure mileage is to fill up, note your odometer reading and drive. Then fill up again (hopefully back to the same level best is to stop the first time it kicks using the same pump at the same station), note the mileage. Subtract the last mileage from the start mileage and divide it by the number of gallons you just added.
Then correct for any odometer error caused by non stock tires.

 

man in black,

Wow! Can you sum up what you did to get good mileage?

 

I meant the larger bore of the primaries on the Holley 600 versus the primaries of, say, a Nikki.

 

Well i stole a carb From Kentetsu and yes he wants it back.
i have a header and dual side exit pipes my car has no cat no muffler and no emissions, and i pre mix only also this might have something to do with it i have a sump pump gas tank so the gas is sucked from the bottom of the tank it may have something to do with the fuel not being turbulent when it enters the pump and the lines to the engine turbulent means air bubbles tiny but air none the less

Free flow and a fresh motor and carb.
clean air filter new plugs and wires cap and rotor tires at full PSI as rated
and no overly tight front rotor hub.

other than that it may be the fresh virgin blood i feed it to keep it from blowing up????