need help with carter AVS carb

[resq302]

Ok, since I have had the carb rebuilt by Dick Katter, I have had an issue of it backfiring once through the carb and then it would take off.  Thankfully, Dick has been trying to help me through this but it still has the backfire from idle to wide open trottle.  If I gradually accelerate, it runs fine and does not backfire.  Only when you go from idle to WOT.  We have increased the jet sizes on the primary jets and now we are trying a larger squirter for the accelerator pump.  I am trying to keep the carb original as everything else on the car is pretty much factory standards.  I was thinking that since we increased the primary jets, that we might need to richen up the metering rods for the power step however, no one makes the three step carter metering rods anymore.  Does anyone know how to cross over a part number to find out what the correct stepping rod I need?  Is it possible to convert a three step AVS carb to the two step AFB carb style?  I really need to get this problem straightened out as my first show is a week from Sunday and my car will be the feature car at the show since I won Best Restored Car of the Year last year.  Be kind of a  if I pull in and the engine is backfiring here and there with it supposed to be the best car last year.

[FLG]

I could ask my carb guy when he gets back from carlisle, or if i see him there ill ask if he might have some. I'll also keep an eye out for them while im there and if ya want can pick em up.

Also found this info on the metering rods, hope it helps..

"AVS carbs use three-step metering rods with corresponding jets. Theseare no longer available as tuning parts, whereas AFB rods and jets arecommonly available. The difference is the AVS three-step rods arelonger, and the jets are deeper. The AVS top cover is also raised forthe required space. Substituting a flat AFB metering-rod cover willallow common AFB rods and jets to be used. The metering-rod springs willinterchange, and the AFB accelerator-pump squirters can be used if theforward edge is ground to the AVS profile."

http://www.moparmusclemagazine.com/howto/155_0305_carter_avs_carburetor_install/pictures.html

[acelondon]

retard your timing 2 degrees, then give it a try. When you WOT it, the engine vacuum is changed dramatically, and it may be telling your vac advance to move to too early. I don't know how youd adjust the advance its self, except maybe disconnect it. I don't use mine. Make sure you plug the line!

Adjusting your initial timing will change your final timing which is too much advance if your getting backfires. Adjusting the advance would keep your initial the same and retard your final timing.

Could also be a sticking valve, but most likely a timing issue.

Cheers!

[John_Kunkel]

Backfiring at WOT is caused by too much air; the AVS is named for the air door in the secondaries that controls air flow, have you tried tightening the adjustment of the air door?

[resq302]

John - The secondary air valve is closed when it backfires.

Acelondon- The vacuum advanced is no longer hooked up and plugged, I only have mechanical advance now.

[MOPARHOUND!]

Were you able to fix this? 

[acelondon]

i always thought backfiring trough the carb is caused by the plug firing while the intake valve is still open. aka, too much advance