Running a 4 port 13b bridgeport with a holley truck avenger 670 (mech. sec.)on my sandrail. Have a huge flat spot on the bottom and boggle in corners. No vacuum leaks, fuel levels and pressure are good, mains are 73/67, Have 1" plenum spacer (primaries shared plenum, secondaries separate rails). Timing is -23. Acc pump pushing max fuel. Squirters drilled for max fuel delivery. Ignition (coils) tested good. I'm a nuub at all of this so I've probably got it all setup the wrong way. Any wisdom would be greatly appreciated. Thanks all.

 

Throw away the non-rotary carb and get a Racing Beat carb. It's calibrated to work correctly.

You are adding way, way, WAY too much fuel.

 

the holley bogs in corners due to the way it sits on the intake. the float bowls sit side to side, not front to back, like on a V8. i would think that lowering the fuel level in the bowl would help, but then u run the risk of starvation when u start winding the gears out.

 

The truck avenger carb has a unique float bowl design supposedly to combat slosh-n-bog and to allow the carb to be useful in off-road applications. For the most part it works great all over, just a bog at the bottom if i stab it. I'm going to try an open plenum spacer today, hopefully it will allow more fuel from the primaries to the engine via the 2ndary runners and fix the bog. I'll update.

 

Ignore "fuel". Think "air preparation".

 

The carb will like the open spacer more, but you prob aren't going to get rid of the low rpm stumble any time soon.
Timing helps but doesn't get rid of it. I'm guessing youre running a muffler? I'm also guessing you also have a power valve and that's why you have such a wide jet spread?
Why are you trying to stab it at such a low rpm? A smaller carb will work better down low but it will choke the bridge.

 

Problem solved. I put in the open plenum and changed the linkage to the secondaries so they open simultaneously with the primaries. No more flat spot at all, starts easy and it runs like a raped ape. Thanks all for your thoughts.