I have read that manual secondary carbs can be used on cars if they fit into a certain catagory, that being less than 3100 pounds, manual tranny or a high stall converter, and with gears no lower than 3.91's. Since my Duster fits this catagory, should I consider maybe purchasing a manual secondary carb? Can the vacuum secondary carb I have (either a 670 Street Avenger or a Holley 3310) be set up to work just as well?

I'm not very carb savvy, so any help is greatly appreciated!

TIA!!!

tell us about your motor and 4 speed / stall headers cam and usage.

Oops, sorry about that! It's a 340 with HP manifolds, .030 over. Street driven, no planned time at the track (yet!!!). Tranny is an A833.

Thanks for the advice, Cab Burge. I currently have 2 carbs here that I can tinker with (if that's possible), and I would prefer to do that, if they will function for what I am looking for, that is. Those carbs are a 670 Street Avenger and a Holley 3310. The 3310 is used, and came with the Duster. It needs rebuilt, also. It also always ran rich, and I had to pull the plugs frequently and clean them before it would start.

I am just looking for the best possible performance from my 340. I had a 71 Charger years ago. I rebuilt a 340 and put it in. I used a carb from a 68 Charger with a 383. It was a Carter, but I don't remember what model it was. But, it had the manual secondaries. The car was definitely heavier than 3100 pounds, and had a stock 727 and stock converter. But, to me the engine responded well when those secondaries opened up, even though I should have been using vacuum secondaries, according to the literature I have read.

As I said, I am just looking for the best possible performance from my 340, using what I currently have, if at all possible.

Thanks for all the advice!

Anybody else???

If you are interested in ET. Mechanical secondaries every time with a manual transmission when you are closed throttle shifting.

I don't care how light of a spring you run in a vacuum carb. It will never open as fast as a mechanical secondary carb.

For your applicatioin, the 670 Street Avenger you already have should be the best carb available. Why do you want something different?

Well, just striving for the best I can get, I guess. I have this 3310 sitting here not doing anything, and I was curious about it's potential, also.