I am trying to get my motor to run for the first time. I think my timing is close and I have TDC but...if the car backfires 'mist' through the carb, some of the mist leaks out of a spot between the intake and the head. This must mean I have an air leak in the intake?

I can't get this thing to run and I don't want to damage my carb with backfiring through it. It is a new Holley Street Avenger - can it hurt anything? I am getting close but the engine will not stay running.

Also, to start for the first time, do any of the ports on the carb have to be plugged?

all of the ports you're not using should be plugged.

mist out of the intake manifold??? That's a little.. uh... questionable.

If you're SURE - you better get that manifold off and resealed. I had good luck despite my amateur install with fel pro gaskets.. the ones with the raised blue ring around the ports.. anyway.

I think backfiring can hurt power valves.. but the avenger is supposed to have something to stop that I think. Hopefully someone more knowledgeable than I will pitch in.

Yes, you need to get that intake leak taken care of first, but I should start and run even with a vacuum leak. If it's backfiring and not starting, it sounds like the timing is a notch off. Marv just posted a good reply on how he sets initial timing, check it out. Good luck in getting it up and going.

I agree with CorkyE about fixing the intake leak first. You don't want it running too lean and do some damage. And I know this sounds amatuerish, but could #5 and #7 wires be crossed?

I'll quadruple check 5&7 to make sure. I pulled the distributor out, pulled the plug wires off, and found TDC again this weekend just for S & Gs but it still does the same thing - fires a couple of times and then shuts off.

Some guys were working across the street and came over when they heard it bust off for the first time - they both independently said that it sounded like it was getting too much air - this could be a combination of open carb nipples and an intake leak?

Would this stop it from running?

I have open headers so I dont have backpressure on the exhaust.

Yes, it could. Block off all open ports on the carb and seal the intake leak and try again. Update us when you do this.

I got a 770 cfm street avenger and when I went to first start my engine my timing was off and its been backfired a lot. Probably a total of 50 backfires on that carb and its perfect still so I don't think that your carb will be damaged at all. Plus I ran it on open headers with no issues for a while. Also check your valve lash if you got that to much than your valves could be stayin open and you'd get backfires and bad performance. And just try to tune it by ear: twist the dist 1 way and if it gets worse twist it the other way