472 HEMI, MP Alum heads, JE 10.5:1, Eagle 4.15 stroke, CompCams solid grind 285S-8, 250/250 @ .50. .557/.540 lift at valve with stock rockers, 108 LSA, M1 intake, Holy 4150 vac secondary 0-80531 with 78 primary jets, 82 secondary, orange box ignition, MP distributor, Accel super-stock coil.

I'm having trouble figuring out why I have a miss on acceleration. It's a street car. It idles fine and drives ok but has a bad miss when I romp on it. Plugs look tan. I've got 1/2" fuel line with an electric pump and return-type regulator.

What should I be looking at?

Plug wires , carbon tracking , a lean condition maybe , valves too tight ?

It's got a new set of Taylor 10.4 MM wires and I doube-checked the valve settings already. I'm guessing the fuel is ok with the plugs looking tan in color

You know what's wierd is I just took the air-cleaner off and took it for a ride and it runs like a bat out of hell. When I mash the pedal there is a slight bog (vacuum spring?)and then it revs thru K4.5 rpm without a miss. At K4K it acts like it wants to go airborne.

Maybe it's jetted too rich for the air cleaner? There's no room to put anything larger than what I have.

I would suspect that the air cleaner base is interfering with something on the carb, or is grounding or arcing at the distributor cap or wires, if removing it cures the problem.
I wouldn't think even a VERY small or restrictive air cleaner would cause a miss; lack of airflow would act more like an RPM or power limiter, where the motor stops pulling. More info on the carb might help: power valve, shooter size, float settings - a 78 primary jet sounds small for 572" and that size cam, but I could be wrong; you indicated that the plugs have color. Then again, idling will color-up spark plugs, where full throttle & cutting the engine will give a more accurate reading - look down a ways at the sides of the porcelain. Another thing to look at is the timing. Is it a miss like 1 cylinder & rhythmic, or scattered misfire, detonation ("rattling"), or ???

arcing over to the air cleaner

I just had a similar problem with one of mine, I changed air cleaners, then I had missing, stumbling, it ended up being the air cleaner was blocking a vent. Blamed other things I had changed, but then it ran like it always did after I removed them. Note to self......don't fix things that are not broken!

There's plenty of clearance betwen the distributer and air cleaner. All the other wiring seems ok as far as clearance.

When it cuts out is does not really seem like one cylinder. It almost seems like a rev limiter, it just cuts out across the board until the rpm drops around 3,500. No rattling or detonation.

It's a 472, not a 572. Holley advertises it as an ready-out-of-the-box carb for a 502 crate motor so I would expect it to be close. Primary power valve is 45 and secondary is 35. Pump nozzle is .040.

I'll keep checking for stuff the air cleaner might be affecting. thanks

I sthere clearance between the air cleaner lid & the bowl vents? Look for clearance at the needle & seat adjusters, throttle linkage, secondary linkage, fuel line if you're running hose.
So, it runs fine without an air cleaner, but installing it acts like a rev limiter, breaking up at 4,000 and shutting it down to 3500, and then it runs fine? Or does it continue to strangle until you remove the air cleaner & restart the motor?
What's this air cleaner look like?

clearance to the vents and throttle linkage, etc look good. The air cleaner is a low profile round. I think it's about 14" diameter.

There car runs better all around with it of. Off-idle is better, full throttle is better. I'm wondering if maybe it has something to do with vacuum. The engine has low vacuum at idle (5-6 inches) and if the engine is choked-off it would create less vacuum accellerating possibly affecting the vacuum advance on the distributer or possibly the vacuum secondaries. Just brain-storming, I don't know if that makes any sense. The distributer is the MP unit. I went with that because of hood clearance. Most of the performance distributers are long.

I think if you have a highly restrictive air cleaner your vacuum will go up. Is the air cleaner a matched set or pieced together. I created a problem trying to use my original 340 lid with a dropped base. Due to the shape of the lid it created a choke point of less than 1/2"

Well, I discovered part of my problem. I went to re-jet the carb and discovered the jets and power valves were swapped end for end from the factory.

But now it has a different problem. If I'm rolling in second gear and romp on it the engine runs strong through all the gears 'till I let off. But if I romp on it from a dead start it sputters and misses until I let off the gas. I can't drive through it.

Could my excelerator pump be too small? It seems like an ignition miss the way it cuts out but it doesn't make sense to me.