I have no idea what it could be, i have a 1973 dodge charger, 318 904 and it has a holley 4bbl vac secondarys, rpm air gap intake, and a orange box. I messed with the timing didnt help, revs just fine in park up to 5500. In drive ill stand on it and ittle pull perty good up to 4200 and like hits a wall and starts popping and sounds horrible, please help. Thankyou..

Could be the orange box or weak valve springs. or something else?

Hookup a small can of gas in the eng compartment to the pump inlet w a 5/16" neoprene hose and try it again. Still cutting out, open the hood and suspend a small container of gas high up from the hood latch like a bag of glucose on a hospital gurney and hook it to the carb inlet and try it yet again. EDIT reread the post and from the descrip it sure sounds like ign. I would check the plugs/wires. One of em might be defective and not be able to support the addt'l load between free revving and in gear. Is that on the road or foot braked in your driveway?

My brother had a 78 Dodge truck with a slant sick. It idled fine but would buck and stall when put into gear. After throwing all sorts of things at it, we tried a known good distributor cap and plug wires on it. It ran great and actually peeled out for the first time!

Im thinking/hoping its ignition i dont wana mess with valvsprings, and wouldnt the float without a load on them? I put new plugs in it but the guy gave me platinums intstead of regular ones, ive had bad experinces with platinum plugs. I also have a accel coil i replaced the stock one thinkin that could have been the culprit. Ill try plugs and then perhaps i put the stock box back on wish me luck!!!

Mine did that when I had a dying fuel pump. Would run fine during normal driving, but stand on it and it would start bucking and surging once the rpms started getting up there.

If the valve springs are stock thats all she will go.The 4400 limit is all she wrote.

Tired valve springs don't cause any popping or rough running issues, at least from my experience - they just limit the upper rpm capability of the engine.

My guess is a bad spark plug wire.

hi
you have low fuel psi or a partialy cloged fuel filter!

is the tach effected?

I just found out that my alternator is shot, so im hoping that could be the culprit, i got new plug wires and fuel pump on it so thats out. tac works but dont seem to be right unless the the rpms are up a lil 1000 or so, and at night with the lights on the tach wouldnt work untill bout 23-2400, maybe alternator is bad??? Im really hopin you guys are wrong about the valve springs....

unplug the tach and try it again.

Valvesprings aren't that hard to change with the motor in the car. You need a few specialized tools and a few hours to do it. A tech with moderate experience should have no problems.

Its a factory four barrel 318 wit 360 heads i would sure hope that hte vavle springs would hold up better than that wouldnt they? I would have no problem changing them im a pretty decent shad tree mechanic, but im hopefully gunna throw an alternator on it tomorrow and let you guys know and go from there...........

Diagnosing is an art. Sometimes it is learned by doing all the wrong things first, sometimes it is by making an educated guess.
Once I had a 73 Challenger that also idled fine, but ran out of breath at midrange. No Tach, so I can't guess the engine speed. The engine was a reringed 440 that went a tire smoking 14.01 at 100 mph in a Charger, so I knew the motor was fine. The ballast resistor felt hot, so I swapped in another known good one. It ran perfectly afterwards. Either the car gods took mercy and lifted the curse on the car or the ballast was AFU.

Well i guess my alternator wasn't bad, i put a new one on, new voltage regulator still not putting out any juice, im going to buy a ballast resistor today and see what happens.....