[rusty duck]

I just bought a nice '37 ford coupe with a 350 chevy engine from edelbrock, using an edelbrock 600 cfm carburetor. I just ran my first two tanks of gas and on the first I got 10+ mpg. I adjusted the fuel/air mix a little and bumped it up to 13.6 mpg. The engine and tranny both have only 11,700 miles on them and they run and shift good. I'm thinking I should be getting 18-20 mpg. Am I right or expecting too much? I drive conservatively and appreciate your thoughts.
Jim

[ericnova72]

What rear gear??

What is your initial timing, total timing, and at what rpm is it fully advanced??

Vacuum advance?? What port is it hooked to, full time(manifold vacuum) or ported??

Any idea what the cam specs are??

[rusty duck]

Eric,
We think the rear gears are 3:08's and the cam is supposedly stock.
At 60 mph the tach reads about 2700, so the gears may be lower, not sure. No tag on the rearend, so will have to jack it up and do the rotation counting process. The other things you ask about are things I will have to determine, I am not a mechanic, although I can take things apart and put them back together pretty well. However, when it comes to the analyzing stuff I am a novice.
Appreciate your questions and will have to get back to you.
Jim

[cobalt327]

HERE is an easy to use calculator. Measure the tire diameter carefully, preferably mark the tire and ground and do a roll out of 3-4 revolutions, measure the distance in inches, divide by pi (3.1416) to get an accurate tire diameter. In another thread just recently, a tire that was measured at 26" turned out to be over 27", so it matters.

The type of driving (stop and go or interstate cruising) makes a big difference in mileage, because every time you are off and back on the throttle, the accelerator pump is working- this will effect mileage a lot, as well.

You should use the smallest shooter and pump arm position that still gives bog-free acceleration. Accelerator pump nozzles come in .024", .033" and .043" sizes as a set under Holley p/n 1475. Your 600 (1405/1406) comes w/a 0.028" nozzle, w/the pump in the middle hole. Moving to the top hole reduces the pump shot, IIRC.

The 1405 is calibrated richer than the 1406. Not by much, something like 2%?

While you are checking things, see what the vacuum is at idle. This can have an affect on what step up spring is needed- you don't want the spring to allow the rods to lift at idle, or the carb will be too rich and mileage will suffer.

[rusty duck]

Cobalt, thank you for the info. I surely do appreciate it.
Jim