cant figure this out_440 pops and lacks power ...

Is there a good ground from the engine to the body? My 68 dart was missing a ground, ran great until I floored it. It ran 13.01 and missed bad the whole way, fixed the ground, went 12.40's and never missed a beat.

Try narrowing the gap on the plugs. If it gets better then the coil is likely weak.

I just remembered another incident......
I am not a drag racer by any means, but I built a big motor for the Charger anyway. 440 block, 4.15 stroke crank. 10.8 to 1 compression, Edelbrock heads, 850 carb, MP '509 cam, 2" TTI headers too. 727 with a 3000 stall converter and a 4.10 SG diff. Long ago I did an electronic ignition conversion.
A local dragstrip had a car show & drag race event and I decided to race the car. I opened up the spark plug gap to .045 thinking the wider gap would make for a bigger spark. I put-putted to the venue to keep the wife from wigging out. So there I was, at the starting line. No burnout really, just a quick spin to clean the tires. The lights came down and I walked it out of the hole to avoid blowing off the tires. As I laid into the throttle, the motor started cutting out. At full throttle it was bucking, sputtering and hesitating. By the halfway mark I let up to about half throttle. I was shocked to see that I still turned a 14.83.
At home I dug in to see what was to blame. Nothing was obvious at first look. I pulled the plugs and closed the gap to .035 and went for a drive. It ran better than at the track, but was still cutting out. I pulled the distributor cap and saw that the air gap from the reluctor to the pickup coil was W I D E ! Its supposed to be set to .008 inch. Mine was at .020, 2 1/2 times the recomended gap. I reset the gap and everything was back to normal!

I've had some of these issues come up too. Too much reluctor gap, dying mechanical fuel pump, poorly tuned carb/distributor have been the main ones I've dealt with.

Mine was weak valve spring's.

Remove a variable...Maybe a friend can let you borrow a carburetor that runs on their car and doesnt have problems...Once you have that squared away, move on to another variable. Do you have a fuel gauge maybe?

Apples to Oranges. My Dart used to do that when I first got it..but it was a 1bbl carb. moving up to a 2bbl improved but the 4bbl woke it up quite a bit.

What kinda carb you got on there? maybe a power valve is blown? You are leaking excess fuel into your manifold?

Does it pop from the carb or exhaust?

I had a car do what you describe and it popped out the exhaust. I picked up a $5 spark checker and put it on a plug. I had someone start the car. At idle I could see the spark. When he pressed the accelerator the spark went away.

Mine ended up being a bad orange MP ignition box. Bought a $20 box at Autozone and it ran way better than it ever did with the old box.

TIME to find-out what your fuel pressure is.

Is your vacuum advance hooked up?? Is it hooked to manifold vacuum?

thanks for all the replys
this weekend is "work on the charger w/e" some facts, the carb is the edelbrock 1401 or 14xx cant remember, its the same on my challenger and it works great, i dont think its the carb. vacum advance is hooked up, wires are on corrrectly, fuel doesnt seem to be an issue,i have a electric pump, it does pop thru the exhaust though, maybe bad exhaust vavles? i'm leaning towards a bad cam. i'll report my findings this week.

I would do a comp check first and look the plugs over again

I will bet it is MEGGA lean when the secondaries come in ..

I was thinking too much pressure with his electric pump and eddie crab.

Eddie crab ?

I thought you would get a kick out of that!

You know the word CRAB was an error in spelling THEN it stuck ... 'specially ferr 'da Bumz

MY experience with this situation .. I have had a combo go lean and fat. Lean was when I was doing some major tweaking on a TQ ... I changed the secondary jets and FORGOT to tighten one down. It fell off(and that cut-off 50% of the fuel in the secondaries) ... then the car was popping and banging SURGING big-time.

Later that month I took it to the track..... muffs, OEM dual-snorkel air-cleaner and all..... it would lazy nose-over when you got into the higher revs .... MPH was not what it should be.

I double-stacked the AC element ... problem solved

THAT situation was going way FAT.

I feel like Al Pacino here.... I'm getting pulled back IN!
One more time... I had a 71 Chevy truck that ALSO ran fine at idle but popped up through the carb on anything over half throttle. THAT truck had several exhaust lobes going flat on the cam. The limited escape path for the exhaust gases resulted in reversion into the intake ports and up through the carburetor.

I have the Eddy 500cfm and the eddy 750. If you put your foot down, maybe you need some more fuel. Is your accelerator pump linkage on the middle hole? Try readjusting it to the bottom hole, it will allow more fuel to come in. Your jets/rods would be another question. They are usually pretty good from the factory but you have some fine tuning in your future to perform. Are there any vacuum leaks? Is the back port on the carb sealed? I have vacuum lines coming off mine and maybe you have a fray or crack in yours. I have but one car and I saved up some cashola to buy an Air/Fuel readout so I can fine tune the carbs.

If you have another carb as you say...doesn't hurt to spend 15 minutes and take it off the other car, all the fuel lines will hook up the same way too.

How many miles you have on that cam? Hydraulic? Solid? If you think its the cam I dunno how to go about checking it. It'd be the blind leading the blind...maybe pull a lifter and check the bottom for damage

Hate to add fuel to THIS fire..
but if the engine IS NOT rebuilt-
He may have excessive slack in the timing chain, or he may have slipped a tooth. Wouldn't show up at light throttle, but would alter the timing enough to cause an issue under load.
Stupid Plastic-toothed 'Silent' drives were known for this kind of issue.

Just my
CC

Also sounds like a weak or broken valve spring, or a worn cam lobe, or worn lifter base with a slight hole causing leak-down with backfire under load....

no its a complete rebuild, i'm going to start back at the begining, and go thru every detail.

Ya Know...I'm leaning toward the Cam Lobes myself.
Reason being-
Did you use an Oil with Adequate Zinc??
Not trying to advertise, but I've seen a couple of 2.2's and at least 1 small block with wiped out lobes because of the newer 'ecologically sound' oils that don't have enough Zinc in them.
I run Rotella in my cars now- save for my Stratus which has a factory roller cam.

Real important in this day and age to know what the ^($*&% they are doing for the 'enviroment'.

Good luck with it!
CC.

Knew a car that did this..was a pin hole in the fuel line where it ran through the crossmember.

Also second poster beat me to it...the bad coil.You try another?I hada Duster that went to acting like that and finly got a real mopar ol timer to come over..he listed looked around and said..you got another coil?I said yes and slapped it on and away we went!

Does the carb have a power valve?

Can you pop in a diff dist?? Or can you put a vac source and watch the plate come around and see if somthing is grounding or if the gap is changing alot.

I ask this because I chased the same deal and did everything from fuel pump to float level, coil, ect only to after a long time find the cause was the advance plate had issues when it was moving in the advance of the dist plate..?????

Who knows, but good luck.

Got it figured out! it was a bad control module and a little tweaking of the timing. runs good now.

but now my aftermarket tech bounces around, it doesnt stay steady

bad ground? hate these gemlins !!

Mine does this too. Bounces from 800 - 1000 RPM but the engine idle is nice and smooth...