help with 440 back firing

[charger2fast4u]

i got a 440 in my 73 challenger.  it started about 2 weeks ago it was running good. i took it out for a drive and as i got on the gas it seemed ok until about 4k-6k not sure of the exact RPM  don't have a gauge in it. but it started breaking up real bad and back firing. so i took it easy on the way home it runs great still at low RPM until you go all out. checked over all wiring made sure nothing was loose spark plugs are 2 months old if that cleaned the 1 fuel filter and replaced the other and tried it out. still the same results now it got worse and anything over half throttle it now acts up what should i check into next i don't think it is fuel issue as i shot flames out the exhaust so i'm guessing something in the ignition. motors a stock rebuild basically with 4,000 miles on it and a tremec 5 spd trans. also don't think this has to do with the motor problem but just incase my turn signals are acting up to one day they work fine the next day they blink real slow or don't blink at all. this started not to long before the motor acted up thanks for any help

[maxwellwedge]

Electronic or points distributor?

[b5blue]

Ether way check advance, check dist. shaft for wobble...grab it and wiggle it around...it should not move side to side. (I had a new re-built do it and it played hell with high RPM)

[charger2fast4u]

it came with a electronic ignition installed when i bought it. from the way it looks i think this is the one i have with the orange box http://images.google.com/imgres?imgurl=http://www.bouchillonperformance.com/images/Ignition%2520Kit.jpg&imgrefurl=http://www.bouchillonperformance.com/BPEelectronic_ignition_kit.asp&usg=__CN4gZJHaWziRZEggAweWjqCEDI0=&h=250&w=394&sz=17&hl=en&start=1&tbnid=UPoO3bsEEsX25M:&tbnh=79&tbnw=124&prev=/images%3Fq%3Dmopar%2Bperformance%2Belectronic%2Bignition%2Bbox%26gbv%3D2%26hl%3Den%26safe%3Dactive

[charger2fast4u]

i checked over the distributor took off the cap cleaned the arking points put it back together and checked for any wobble couldnt budge it at all. what should i check for next?

[greenpigs]

Check the air gap. It sounds like old gas.  I have had the exact same issue and I just had to run the old gas out. After a re fill with 94 the problem went away. It wasnt knock either as I used the same octane gas.

[charger2fast4u]

i don't think the problem is old gas as this was my daily driver up until this happened. also i just filled it up 2 days before the backfiring started taking over at low RPM's to. is there any way to confirm it isn't something in the fuel system? i think it has to do with the electrical system because if it's backfiring that means unburned fuel is entering the exhaust am i right?

[mikepmcs]

fuel pump, distributor, spark box... time to grab a fuel pressure gauge and a fluke meter and start checking pressure and voltage...... and you said you checked the plug wires right(as in threw another set on there). I'd really go over that electrical wiring one more time with a fine tooth comb. Check around all your splices etc......

If you did suspect gas and wanted to check it, throw a gallon of toulene in there, 114 octane mixed with your already exisiting fuel, you should definitely notice a change.

[Back N Black]

I suspect coil is weak under load. 

[Bob]

Mine was the cam. 

[b5blue]

This is a points dist.? Check for a wet (fuel) cylinder.  

[mikepmcs]

Mine was the cam. 

I can't say that didn't creep onto my mind as well as the other stuff, but......  I'm hoping it is something more simple than that. My fingers are crossed for you. 

[Bob]

Mine was the cam. 

I can't say that didn't creep onto my mind as well as the other stuff, but......  I'm hoping it is something more simple than that. My fingers are crossed for you. 

I was hopeing the same thing. Even had my toes crossed. Cam 

[charger2fast4u]

i didn't replace the spark plug wires just checked for any burn marks exposed wires and loosness. i have a fuel pressure gauge hooked up in the system along with a regulator reads around 5-7 PSI which is in the normal operating range for a mechanical pump right? i hope it isn't the cam going out i don't know if they used the stock cam or put a new one in when the motor was rebuilt. i'm leaning towards the ignition system being the culpret. one day it ran fine the next day it started backfiring at high RPM and a week later after driving it easy the backfiring crept down to anything over half throttle. i will try putting new plug wires and new coil on the plug wires are a chrysler reproduction with the logo on them last owner put them on and the coil isnt the best looking either. what's a good coil and plug wires to go with theres alot of options i was thinking of getting a MSD blaster 2 coil and what plug wires sould i go with

[greenpigs]

Firecore 50 are good wires and many use NGK plugs. I use a MSD 2 blaster coil as well plus the other parts mentioned.
Make sure you let them know what coil you are running so they use the correct style boot as each wire set is custom fit. BTW FIREFIGHTER3931 is a Firecore 50 dealer.

[b5blue]

  PM Ron

[Khyron]

Mine did the exact same thing, I replaced the distributor and fixed the issue.