Poor Gas Mileage

Tune-up parts and technique suggestions in this thread. As others have mentioned, you will need to do some careful diagnosis and repair, paying careful attention to the distributor and carburetor. Along the way you may want to do some upgrades, such as the HEI upgrade .

It should not be necessary to re-engineer or modify your Holley 1920 carburetor -- leave the soldering, drilling, etc. for advanced tuning once you've got things working the way they're supposed to, otherwise you'll have no baseline to get back to and can wind up getting "lost". You may very well have a heavy carb float; they are made of nitrophyll (foam) and over the years they will absorb gasoline. Also, the brass retainer rings for the two power valve check balls can fall out of the metering block, dumping a ton of fuel into the engine at all times. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

Check and adjust the valve adjustment as well.