popping on 440

[kenkarner]

here we go again... my sons 440 in a 68 RR has a popping over 3000 rpm through the exaust. you can hear it more than feel it. we are chasing the problem and it is getting better but if you have ideas please let me know, we have... new malory dist, new carter carb, 3rd set of plugs, new wires, new coil, new ballast resister,no bent valves, good springs, we have tried 3 different carbs. could i have a manifold leak? weak springs? the entire engine is mopar parts, lifters,cam(purple) balanced from the inside out now it only does it in 1st and 2nd---3rd and 4th are fine,,has blue elect pump 3/8 fuel line It has to be some small something because it still pulls like crazy, will burn the tires off, runs low 13's on street tires but I just hate the sound of the popping, could we need more carb? could it be lean? I have adjusted with vacume gauge.

[1972roadrunner]

double check your firing order, and make sure your timing is correct...

my .02

[sundrop_440]

what temp. are you at when this happens? If it's a little hot you could be getting a little vapor lock , does it happen all the time or if you run through the gears and start over is it still there that would be one way of pinpointing it.

[sundrop_440]

what electronic control unit are you running there's a chance it could be that I had a simular problem awhile ago but my popping was alittle less consistant I hope this all helps

[Bagherra]

I had popping coming out of the exhaust and it turned out I was running very lean. Opened the mixture screws on my Demon carb and it solved the problem.

My popping took about 10-15 minutes of driving to show up (engine warming up) and then it popped a lot. Once I solved the lean mixture issue, the pops completely disappeared.

[6 packin]

It may be a lean condition. What is your total timing? Whats your compression. 99% of the time that backfiring is a a timing or carburation issue. You have had a few carbs on it, still there. I have heard allot of bad stuff from mallory dist lately. Maybe swap in a old electronic one to check. Does it have vacum advance/ Probably not, but if so youmay be connected to a wrong vacum port. Un plug it, plug of the source see if that helps.

[creative1]

my 440 was doing the same thing, kinda... ran good when judt driving... at all speeds. but under load (hard acceleration) at around 4000 rpm, all hell broke loose... popping, loss of power, etc. tried timing... adjusting the POS edlebrock carb, rerouting ignition wires, pulling my hair... lol. turned out the thing was running out of gas. not sure why, but i cured it with the following:

adjust floats to as close to specs as possible, both float level and drop. my level was about 1/32nd inch low, and the drop was about 1/16th inch high;
took a 3/32" drill and carefully drilled the float needle jets with it. the specs on a 1407 eddy carb are 0.935, which is 3/32. (they were maybe .005 small);
replaced the fuel filter.

after doing all these things, i took a fuel pressure gauge and put it in the fuel line at the carb, then made some test runs. lowest fuel pressure was around 5 psi, which is about a 1 lb drop from normal pressure of 6 psi. i havent run it to 500- rpm, but it goes through 4800 really good

another thing that can cause this is point bounce if you have a points distributor, although that doesnt usually happen till higher rpm. if you do have points, the condenser may be causing it too. if you have an eletronic distributor, though, i would put my $$$ on fuel supply. oh... as long as your fuel pressure isnt more than 7 psi on a carburetted engine, DO NOT put a regulator on the fuel line. they just cause unnecessary restriction to flow.

[kenkarner]

thanks for everyones input, I will try some more things and let you know

[creative1]

ok... so i lied. my popping is still there. im at my wits end. it does seem to only do it under hard (???) acceleration with light loads now, though. by that i mean doing impressive burnouts on rain slick streets. gonna try disconnecting the vacuum advance and see what that does. i know i sure cant figure it out, and it is embarassing to get that good-sounding engine starting to talk, then have it shooting craps like that. maybe what i need to do is just find a deserted stretch of rainwet blacktop, put my foot in it and hold it there till something breaks. maybe then i will know?

[fastmopars .inc]

are any of those new products you listed made by accel? the coil or the wires would probably be the problem.

how do the plugs look? third set of plugs? are they fouling? melting? popping is usually a lean condition, or at least that's what it was on my 440. but the popping was occurring at 6000

[kenkarner]

plugs look good, I am saving them for my 413. msd coil, accell 8mm wires, when I have time I am taking off the carter and try my 750 doulble pumper that is proven on another engine

[fastmopars .inc]

change those wires, you'd be better off going to the junkyard and getting some 30 year old mopar wires. i have tested the resistance on most brands of wires and accell is worse than any cheapo sets you can get from auto parts plus and etc

the carter is trash when compared to that holley for that motor.
the 440 will probably love that carburetor.

[1972roadrunner]

Originally posted by fastmopars .inc
change those wires, you'd be better off going to the junkyard and getting some 30 year old mopar wires. i have tested the resistance on most brands of wires and accell is worse than any cheapo sets you can get from auto parts plus and etc

you must have had a bad set of wires, cause accell is the best in my book. we have the accell 300+ racing wires (8mm) on my bro's 440, and we did have some popping but it was because of the points and carb (carter AFB). converted to electronic ignition, reset the timing, and most popping was gone. switched to a holley 650 double pumper, and the popping disappeared. this was on the same set of accell wires too.

another problem we had one night, was right after changin the old plugs to some bosch platnum...we got 2 and 4 mixed around and there was popping out the exhaust as soon as it fired. rechecked firing order, and fixed the problem.

not only that, but i have the accell blue 7mm wires on my 340. no popping or problems there, and resistance is still low. can't remember an exact number, but it was low. (these are all spiral core that we use)

[1972roadrunner]

forgot to mention, i also have an accel super coil on my 340, with absolutely no problems. (mopar gold box)

the only thing i have against accel might be their prices in some things like distributors... a little high, but i like the quality and haven't had a problem.

BTW: that coil is over 5 years old. it was on the car when we bought it!

[6 packin]

Taylor and MSD maks some good plug wires.

[dwc43]

We have run accell 300 wires on our race cars with the msd 7al2 and high vibe coil with no problems what so ever. Good set up with a recurved mopar dist. amd Champion race plugs.

[fastmopars .inc]

yeah, the cheapo accel coils (stock replacement stuff) is the worst, they go all the time.
the cheap 8 mm wires are horrible. these are what i tested and have 5 times the resistance of oem wires. remember what i said about the junkyard?
now imagine what your 7mm wires are like.

the 300 plus wires are good but i worked at a performance parts store and i seen more defective accell stuff come back than any other brand.
the 300 plus wires are 8.8's. as far as resistance goes, they are better than the top taylor and msd wires i tested.

i wouldn't put too much trust in them. i've had cars that i thought ran good, and now i have an msd and i know the difference.