engine bog problem

[plumsun3]

Looking for suggestions to help on engine bog.
Have mild built 71 440 R/T. Had problems with edelbrock that was on car when purchased.
I had a TQ 9801S rebuild, after installation car still bogs at around 3000 rpm. Idles fine and goes like hell otherwise.
Should I be looking at distributor. Has mopar electronic unit with orange box. Read advance could be problems. Does
a performance improve timing. I was told cam is mild lift crane, stock heads and springs,  has headers w/ 3" exhaust.

[XH29N0G]

Can I ask for clarification on the 3000 rpm bog and the other behavior of the car.  What I interpret from your description is that if you mash the pedal from a stop, it does fine (no bog, goes like lightning, but if you mash the pedal from 3000 rpm, there is a hesitation/bog and then it recovers and again goes like crazy.  Is this accurate?  If it is, I would think it is something with how the carburetor is set up.  An effect at 3000 rpm could be related to fuel delivery and a transition between between a cruise circuit and to the main circuit.  It may be that the accelerator is already depressed to keep you at 3000 RPM and when you hit the throttle there is not enough left in the accelerator pump to make up the difference.  There are people on here who know a whole lot more than me, and should be able to tell you if what I said has any merit at all.

Timing and the timing curve will have an impact on performance, but you will need to provide additional information about the timing (initial, and what the curve looks like) for people here to advise. 

[Dino]

I had something similar going on with my TQ a few years back and it turned out to be the floats were not set right so check them out. There's different settings for phenolic and brass floats. I should have the measurements somewhere...

[plumsun3]

It acts like the transition to secondary opening that it's starves out. The Edelbrock that was on there was really terrible at that.
Guaranteed carbs down here in Florida did the rebuild on the TQ, they seem to be competent and have a good rep.
Since both carbs have same issue I keep going back to the distributor. I use car as a cruiser but it acts up on highway at about
60/65 mpg and the power loss causes me to pull over till it recovers, At speeds under 60 it's just fine and will accelerate like a r*ped ape.
I run a stock fuel pump backed up with electric for startup. Car starts up at just a flick of the switch.

[John_Kunkel]

Why do you think they call it the Thermobog? 

Air door and metering rod adjustments are critical.

[justcruisin]

If it's a bog and not a miss it is probably fuel related. I would put a gauge on the inlet to the carb that you can read while driving to insure fuel pressure, if OK borrow a known holley or the like, or go out and buy a quick fuel/ proform/ holley HP which suit your build and plumb up an o2 gauge, money well spent IMO.

[plumsun3]

Thanks all for the information. guess I'll try with float and pump adjustments first. I bought this identical 9801S aftermarket carb. from a speed shop back in '74 and installed on a built 440 in a Challenger. Carburetor performed fantastic. never felt secondary surge like it on any other brand including Demons on the street. Holleys I've had always run well, but never exceptional. I'm tearing front of engine apart this winter for some more modern component upgrades, perhaps address fuel system to monitor feed and pressure then.

[John_Kunkel]

Again, the secondary air door's sole purpose is to prevent a bog when the secondary throttle blades are opened. The door is held closed by a spring and the spring tension is adjustable.....too little tension and the door will open prematurely causing a lean bog.

[Nacho-RT74]

[XH29N0G]

As explained, I agree too, but I suspect the issue could still be the transition (float levels could affect this).  The way I see it, the issue is either it is not getting enough gas which could be transition or accelerator pump, or that it is getting too much air, and the way to optimize it is to walk the line with the most air and gas.  I do not have a clue as to what is the most likely (and therefore, first place to look).

[BSB67]

As explained, I agree too, but I suspect the issue could still be the transition (float levels could affect this).  The way I see it, the issue is either it is not getting enough gas which could be transition or accelerator pump, or that it is getting too much air, and the way to optimize it is to walk the line with the most air and gas.  I do not have a clue as to what is the most likely (and therefore, first place to look).

Without knowing in what context it bogs at 3000 rpm, it is difficult to even try to help.  Missing too much information to really be helpful

[Highbanked Hauler]

   I have been dealing with a "bog" situation  on the 440 six pack  and it turned out to be the dreaded ORANGE box. Changed that and it improved greatly. There is still more to go  but no more bog above 50 mph.

[plumsun3]

I've been suspect on the wiring on this car since I purchased last year. Owner gave me a ton of literature and there were a number of notes apparently given to repair shop. Tracing the cd harness shows that it's not wired as the diagrams I can find. The box is a 4 pole, 2 leads to distributor, the one to ballast seems right, but last wire is connected to positive coil terminal. I changed wire to negative as per diagrams but engine doesn't fire there at all. Ballast is new, orange box was on car.
Puzzling!

[Nacho-RT74]

You could burnt the ECU, conecting the black traced yellow wire from ECU to + lead of coil

[plumsun3]

Wouldn't it be dead, but it starts right up on positive lead and runs. I'm still trying to tackle the hesitation issue at 2,500/3,000 rpm. Stills seems to me electric rather than either of the 2 carbs I had on.