Jeep Strokers

I am stuck with a stoker motor that runs great at idle and bogs, stumbles and backfires under any kind of load. Here is the set-up and scenario, if anyone can help I will send motor oil in laue of flowers.
4.6 stroker, clifford intake, holley 470 CFM Truck avenger, MSD Offroad box, Coil, and Distributor. Cam is a bit aggressive.
The problem started a few weeks ago as I noticed the engine would stumble under load in third and fourth gear. The stumble and/or miss would last for about 500 rpm's and as I let off the throttle the motor would start to run well again. I took it to a friend who tried to adjust the curve on what was a DUI dizzy. He also adjusted the jets on the carb down a few sizes. I retrospect he got stuck as well. He reccomended I go with and MSD set up. "The motor wasn't burning all of the fuel and couldn't keep up"?? I took his advice bought and installed the MSD set up. Tonight I set the timing up and noticed something seemingly strange. At idle the motor seemed to really like 18 -12 BTDC. Anything less than 12 and it would being to bog. I set it at 12 and took it for a spin. It has never run worse and is now undriveable. As soon as the motor was put under ANY load it stumbles and even backfired on me. I'm a complete rookie but it feels like the motor is loading up on fuel??? In neutral the motor sounds good and revs like a champ. Another problem I had and remains is that when it's cold it poars soot out the tail pipe along with black smoke. It so bad it leaves a huge black mark on the driveway. Once the motor is warm the soot and smoke go away. Running rich??? Tonight this problem seemed to be even worse.
I don't know where to turn from here...any advice?? PLEASE?!?!
Thanks

you should have 2 fuel meters on the front of the carb try screwing both of them all the way in. if i remember right that'll lean out your fuel or maybe it leans out the fuel at idle...i can't remember it's been 2 decades since i messed with a carburator.

here try reading through this

http://holleyrebuilds.com/carburetor_tr ... oting.html

Thanks for the link! Is anyone running a Holley 4150 or Truck Avenger on thier Stroker? If so what size jets are you running?

I'm running the same carb and manifold, it's very rich on the idle curcuit, I have about 100 miles on mine , and too many other projects. I turned the idle screws on mine in and I lose rpm and it stalls so the power valve is ok.If you can turn the screws all the way in and it still runs the power valve is bad. I set the idle screws at one and quater turns out . What are you using for a fuel pump? I'm running a regulator at 3-5 pds.I also turned the electric choke to the leanest setting, helped some but not enought. I need to set timeing and reset the valve lash. I'm also going to a motorcraft 2100 two barrel 114 venturie,I don't have the time to mess with the holley at this time.Holley has had some problems with the metal make up of some carbs and inside the float bowels will be all flaked might be worth looking at.Keep me posted and I'll find some time to work on mine and see what we can learn.

I'm running rich as well. It's been an ongoing problem. The motor will stall so I think my valve is fine. It was actually stalling until I was about a full turn out. The screws are set about the same as yours. Fuel Pump is a Holley rated between 4 -7 psi. I think I'm pretty close on the idle mixture. My existing problem is when I put it under any kind of load it bogs. To the point it's not drivable. It sounds/feels like it's loading up on fuel. Maybe the Squirter or Jets? I shooting a bit blind without a gas analyzer and vacuum gauge.
I'm new to carb tuning so I'll keep messing with it.

i honestly think your jets are way to big...if you can i'd go down a couple more sizes

I'm using stock jets, I need to make sure that the secondaries are closed at idle. I'm running the same ign system as you, plugs are gapped at .055 i may go to .060. my next move is to check my lifter pre load, because i may not have enough, making for some extra noise,and rough idle.

I gapped my plugs to .50 and didn't notice much difference. When I retard the initial timing to stumbling gets better but it's still backfiring and stumbling under load. It just takes longer (more load/throttle) than it did before. What should this tell me? From a layman's perspective I'm still looking at a timing/ignition issue or could it still be the carb. I also check the resistance on the wires, here is what I found:

1.) .713
2.) .527
3.) .414
4.) .348
5.) .726
6.) .465

Is cylinder 1 & 5 to high/bad? Seems like quite a variation but too much??