Carb troubleshooting

[wtm442]

The fuel level on the rear sight glass looks like it doesn't make it up to the bottom of the glass, but there is fuel back there. I know they should both be half way up.

Wrong. With the engine running and the sight plugs removed, when you rock the car gently (just a bump) a little gas should just trickle out of the hole. Forget the plastic sight glasses. They are just a fire hazard in my opinion.

After making the levels correct, go for a short ride. Stop and remove the sight plug and check the level again.

Now go and adjust the idle screws for smooth idle and best drive-ability. Usually that is at the max vacuum point, but not always.

I doubt that you have a blown power valve since it idles smoothly. It appears that you also have to set the fast idle screw and/or the choke setting.

Sounds like you are percolating the gas in the carb bowls due to heat from the manifold. Adding a spacer between the manifold and carb will help cool down the gas in the bowls, as long as you currently have some clearance between the air cleaner and hood. You can check by putting wet towels underneath both carb bowls and see if the continues to run longer than 5 minutes from a cold start.

One of the best Holley carb book IMHO is Super Tuning and Modifying Holley Carburetors by Dave Emanuel. After you get that book, read it ... and then read it a second time.