RB Back fire

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mrtires24

mrtires24

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Well I have been driving my car for a couple monthes now, but now it back fires like crazy. It will idle fine, but when I put my foot down at all, it just starts to back fire, and misses sometimes. All the wires, and plugs are new, rotor is new, cap new, distributor new. No vacume lines have come off, and the distrubuter is tight and has not moved. New carb, I bought a power valve because my buddie thought that might have gone. I put it in, and nothing. What do you guys think. The motor is pretty much new, and there are more new things on it that used.

Phil
 
No ideas anyone?

Do you think it could be that the carb is screwed up. Its new, I could warantee it. Why would it start doing this without any changes done to the motor?

Phil
 
I havn't pulled them yet, but they are brand new as well. i am guessing that they will be rich seeing that there is unused gas burning in the exhaust ( back fireing)

Phil
 
Thrasher said:
Perhaps it's running far too rich? What's the motor setup, and what carb do you have on it?
Click to expand...

440 bored 30 over
forged magnesium pistons
Torker 2 intack
Electronic ign ( out of 73 and up)
750 double pump, with vacume secondaries holly.
 
Why would it start running to rich now, when I have been driving it for the last month with no problems?
 
Hey Phil, couple things to check. Check your ignition timing just to make sure then you could replace the coil, your secondary voltage could be low.

Terry
 
I had a ballast resistor that started to have a very high resistance vs. completely barfing and caused the exact same problem. Check it out with a multi-meter. Of course that would be caused by a low primary voltage.
 
demon seed said:
Hey Phil, couple things to check. Check your ignition timing just to make sure then you could replace the coil, your secondary voltage could be low.

Terry
Click to expand...

I will do it once I find a timing gun to barrow.

Mine are broken, ARRRG.

I do have a couple extra coils kicking around, I can try that.

Thanks
 
ramcharger said:
I had a ballast resistor that started to have a very high resistance vs. completely barfing and caused the exact same problem. Check it out with a multi-meter. Of course that would be caused by a low primary voltage.
Click to expand...


What should the balast resistor read for voltage???
 
Longgone said:
Is it backfiring through the carb or exhaust?
Click to expand...

Exhaust.

Does it throught the carb only once in a while if the RPM's get to a certain point. But because of the way it is running so poorly, I don't like to bring the RPM's High untill its fixed.

at idle its OK
at 1000-1500rpm it starts to backfire out the exhaust
1500-2500 it is nothing but backfiring out the exhaust with a bit of a miss on the engine once in a while. it will start to back fire out the carb here too, but only once for every 20 exhaust backfires at least

Phil
 
I assume it have to be unburned fuel getting through the exhaust.

What can cause this?
A bad plug wire so that the spark jumps to the block or the head instead for to the spark plug. A damaged wire of the heat from the headers
A bad or jumped timing chain? But that one is new!
A bad coil ?
I`m thinking loud here, as you may notice....ok,ok maybe I shouldn`t LOL
Doesn`t it have to be a missing spark that causes backfire through the exhaust?
 
swedefish said:
I assume it have to be unburned fuel getting through the exhaust.

What can cause this?
A bad plug wire so that the spark jumps to the block or the head instead for to the spark plug. A damaged wire of the heat from the headers
A bad or jumped timing chain? But that one is new! Not only new, but it has a double timing chain!
A bad coil ?
I`m thinking loud here, as you may notice....ok,ok maybe I shouldn`t LOL
Doesn`t it have to be a missing spark that causes backfire through the exhaust?
Click to expand...

i was talking to my Uncle who is a mopar freak, He said it sounds like it might not have enough fuel, He said if it was too rich, there should be some smoke coming out of the tail pipes. I thought this seamed weird, I am going to go outside and test stuff shortly.

The wires are all new, and are not touching any headers. They all look great, I will spray some water on the wires to see if I can get them to arc, but I don't think that will be it

maybe it is the coil. a couple people have mentioned that.

Phil
 
Check to make sure that the plug wires are on correct. This sounds like you could have crossed a couple of them when you put new plugs in or changed the distributor cap.
C
 
Some of you guys were on the right track.

I could notice at idle that it had a miss coming out of the Drivers side tail pipes, but the pasanger side was fine without a miss.

I tried to adjust the carb a bit, but then stoped because if it was the carb it would be doing it on both sides.

You could here a small tick once in a while coming from the drivers side engine as well.

I pulled all the plugs and tested for spark, and they all had spark, some better than others. I put the plugs back in, and while it was running, I would pull the wire out of the dist cap one at a time starting with 1..3...5..7

The engine ran worse when pulling 3, and 5 but pretty much ran the same when 1 and 7 where pulled. So I then switched #1 plug, with #2 plug and tried it again, and this time it ran wors when # 1 was pulled and ran the same when #2 was pulled....meaning I had a pair of bad plugs. I ran out to Crapy tire ( For those americans out there..its canadian tire parts store..but they suck) and grabed a pair of plugs just to see if it would make a difference.

and presto, it runs fine with no backfires.

Thanks again for all your help guys.

:)

Phil
 
Great news Phil, now get out there and
burn some rubber. :burnout: :thumbup:
 
mrtires24 said:
Some of you guys were on the right track.

I could notice at idle that it had a miss coming out of the Drivers side tail pipes, but the pasanger side was fine without a miss.

I tried to adjust the carb a bit, but then stoped because if it was the carb it would be doing it on both sides.

You could here a small tick once in a while coming from the drivers side engine as well.

I pulled all the plugs and tested for spark, and they all had spark, some better than others. I put the plugs back in, and while it was running, I would pull the wire out of the dist cap one at a time starting with 1..3...5..7

The engine ran worse when pulling 3, and 5 but pretty much ran the same when 1 and 7 where pulled. So I then switched #1 plug, with #2 plug and tried it again, and this time it ran wors when # 1 was pulled and ran the same when #2 was pulled....meaning I had a pair of bad plugs. I ran out to Crapy tire ( For those americans out there..its canadian tire parts store..but they suck) and grabed a pair of plugs just to see if it would make a difference.

and presto, it runs fine with no backfires.

Thanks again for all your help guys.

:)

Phil
Click to expand...

Glad you got it going again without a miss. It would be wise to go back to the store and buy 6 more plugs because if two were bad ,chances are the other 6 aren`t far behind. I find Autolite plugs seem to hold up a little better than the Champions.
 
Longgone said:
Glad you got it going again without a miss. It would be wise to go back to the store and buy 6 more plugs because if two were bad ,chances are the other 6 aren`t far behind. I find Autolite plugs seem to hold up a little better than the Champions.
Click to expand...

i will be doing that. The original set where brand new. Maybe have 600 miles on them. V power...I forget the brand. I bought Chanpions ( 2) but I think I am going to buy a full set of 8. Do you use autolite in a 440?

Phil
 
Mr. tires, im not surprised that your car was having electrical problems. If wiring is messy it will only perform that way.
 
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