one plug not firing

[gtxrt]

number 3 spark plug not firing. changed plug changed plug wire and did a compression test. any ideals ? 440 engine.

 

[WileERobby]

Good compression, good wire, good plug. OK. Did you check the cap & rotor ? ( assuming the wire is not arcing to adjacent cable or metal )

 

[gtxrt]

Good compression, good wire, good plug. OK. Did you check the cap & rotor ? ( assuming the wire is not arcing to adjacent cable or metal )

what I just did was take the plug out and it was firing while I was watching it. so it must be running rich for some reason. I only had only 3 other plugs out so far and will have to check the rest. heading to go to work now. if the carb is too rich it should be more than 1 plug wet right ? seems it starts running bad after I get on it and then the plug is missing.

 

[WileERobby]

"so it must be running rich "... well, what color is the electrode ? You're stating an electrical issue then a fuel issue, without complete diagnosis. You're jumping to conclusions, and not providing enough information.

 

[tonysrt]

You didn't mention what ignition system you're running or even what engine. Basic information may help with a diagnosis. I had a 55 Chevy 265 and plugs would foul slightly. I changed to a Mallory dual point distributor and cured my problems. Electronic ignition wasn't available then like in the 70's. I'm talking early 60's.

 

[WileERobby]

You didn't mention what ignition system you're running or even what engine. Basic information may help with a diagnosis. I had a 55 Chevy 265 and plugs would foul slightly. I changed to a Mallory dual point distributor and cured my problems. Electronic ignition wasn't available then like in the 70's. I'm talking early 60's.

He says 440, but that's about all we know.

 

[gtxrt]

just came back in all the other plugs are good just the 3 plug is flooding out and not firing can see gas on the plug. mopar dist. small solid lifter cam. can't be ignition if the plug is firing when I am watching it fire ?

 

[gtxrt]

sorry trying to do these in a hurry before I go to work you know how it is going to work and thinking about your car not running right.

 

[RemCharger]

Stock .035 plug gap?

 

[lewtot184]

One single plug gas fouling but others ok doesn't sound right. Maybe it's oil fouled?

 

[gtxrt]

no oil just gas. .035 gap. i put a plug in the 3 cylinder, then took another plug put in the 3# plug wire and started the car and watched it had good spark.

 

[gtxrt]

with good compression can't be the valves ?

 

[dadsbee]

Why I run all my plugs through a plug tester at 100 psi to verify spark.

Did you actually put a different plug into this cylinder to see if it runs?

 

[gtxrt]

Why I run all my plugs through a plug tester at 100 psi to verify spark.

Did you actually put a different plug into this cylinder to see if it runs?

yes two different ones plus the first one . can't have 3 bad plugs.

 

[ruffcut]

Sounds like oil fowled. It will have gas on it even if it's oil fowled. Time for a compression test. Betting that #3 is down a bit. Could be a broken ring? Time to start digging deeper if it's a high mile 440. JMO ruffcut

 

[gtxrt]

Sounds like oil fowled. It will have gas on it even if it's oil fowled. Time for a compression test. Betting that #3 is down a bit. Could be a broken ring? Time to start digging deeper if it's a high mile 440. JMO ruffcut

i will check again the oil would have to be clean looking it is not black looking. that would make sense oil fouled or if not then valves. how would i tell if it oil and not gas ?

 

[RemCharger]

You said you checked compression and that ruled out a bad lobe I thought.. maybe not

 

[gtxrt]

it will run good for a short time with a fresh plug but the more i can on it then it fowls. i can check the lash it is a solid lifter cam. if i ring was bad it it should be smoking out the tail pipe right ? i rebuilt the engine about 1500 miles ago but that was eight years ago i just bought the car back and put about 500 miles on it it was fine. my friend i sold it to and bought back from only put 200 miles on it in eight years.

 

[gtxrt]

You said you checked compression and that ruled out a bad lobe I thought.. maybe not

yes, but am going pull all the plugs and check again for compression

 

[lewtot184]

If it's a shiny wet black more likely than not it's oil. Too much fuel on a healthy cylinder will be a flat, dry, sooty black. Get a picture.