What is up with this gas mileage???

[Oldguy]

Sounds like you're getting back fire from the engine going lean. I think you're right and you need bigger jets. Good thing you're going to check. Good luck Mike

[Bubb]

one difference is the carb base gasket. the old gasket was oblong the new one fits the bottom of carb,
probably why I had vac on idle before.

So you're saying that the carb base gasket can cause vacuum at idle? I ask because I have a vacuum at all ports at idle. Well, at least the two possible ones that I could hook vacuum advance line to. Didnt check the bigger one coming from PCV.

Brad

[JeepersCreepers]

Sounds interesting, did u check your timing too?

[Bubb]

Yup. Timing is spot on.