Fireball out of Carb

[OhBuoy]

I have this posted on CobraForum, and have had great input there, but looking for more ideas...

I have a 302 that was rebuilt, it has a Holley 1850S carb, MSD distributor, MSD ignition and Edelbrock Performer RPM intake. First attempts to start were close but futile with a fireball comming out of the carb. Yesterday, we discovered one vacuum port on the carb was open. I plugged it, and subsequent attempts to start were easier, but some yeilded a fireball still. However, I was able to get one good start by depressing the pedal and backing off to about 1/4. After a good 30 second run, I knocked the pedal free (it was stuck, will have to work out that kink) and it died. No fireball, but it died. Subsequent attempts yeilded the fireball.

I have verified that it is at the #1 plug at TDC. Could be 180 out, but then it would not start, right?

I have triple checked the wiring according to what the builder stated the timing order should be.

I do have two holes in the back of the heads open, apparently for the air pump, I was originally told they could be left open, but the forum consensus, along with my gut is they need to be closed.

I have not set the float levels, and quite honestly, with flames coming out of the carb and open headers, I am a little cautious of doing this at this point. Something tells me that adjusting them to the point where fuel barely comes out of the site holes at this time would take care of all my worries with the car, the only thing is, it would not be the way that I want to take care of them (up in flames).

The only vacuum source on the Performer Intake that I was aware of is the port at the neck where the carb attaches. Am I missing something there?

Also, I have a manual choke. If I close the plate, it will not start. Half open seems to be a key, but will backfire occasionally. Full open is definately great balls of fire.

The neighborhood kids are having a blast watching this. I quite honestly, am getting a little nervous.

BTW, engine builder will most likely not be much help on this unfortunately.