PoorPersonWithADatsun Posted March 28 Report Share Posted March 28 I put new spark plugs in my car about a year ago, today when driving I noticed my car was running a little rough, I figured it may have been because I haven't driven it in a while, but it got worse over time. Cylinder #3 was not contributing, and after confirming compression and spark, I threw in a spare spark plug I had as the old one seemed wet. There was no buildup of any kind on the old one, just wet with what I'm assuming was fuel. Amazingly, that one spark plug was all it took, and we're running smooth again, however it seems odd that a spark plug would foul after only a year, especially foul with what I'm thinking was fuel. I'm assuming that my air fuel ratio is a little richer than stock as I have a 32/36 carb, but is that enough to foul plugs or could something else be causing this? Would running a different type of spark plug help? (I'm running standard NGK copper plugs). If not, would I need to change out the jets in my carburetor to reduce the air fuel ratio? My ignition coil is also the original, although it still seems to function fine and the spark is strong. I live at around 6000ft so there is less air up here as well. Thank you! Quote Link to comment
Crashtd420 Posted March 28 Report Share Posted March 28 Being a 6000ft it could probably use a little adjustment but having 1 plug foul not all 4 seems suspect..... You'd think if you air fuel was off it would effect all cylinders..... The only thing the comes to mind are counterfeit plugs from Amazon or ebay.... Where did you get the plugs ? Quote Link to comment
datzenmike Posted March 28 Report Share Posted March 28 Six thousand feet will run rich for sure. A couple of thousand not much worry, but 6 is a lot. My 710 was from Nevada (average 5k feet) it had a 99 jet in the Hitachi primary. I noticed that in the mountains on long trips I got better mileage than at home. I'm at actual sea level where the air is like syrup. I got a local L20B and it had a 112 jet, so I put that in. What a difference! You could actually feel it. Thicker air needs larger jet and the opposite is true also. Best way to dial it in is a wide band air/fuel gauge (which I now have) but other than that I guess reading the plugs. They should be light tan. If running rich the plugs will have soot on them from the extra unburned gas. Dialed in properly your gas mileage will also improve. Quote Link to comment
Stinky Posted March 31 Report Share Posted March 31 I don't care how strong your spark is....if you are running rich, you'll foul plugs Quote Link to comment
Stoffregen Motorsports Posted March 31 Report Share Posted March 31 Modern spark plugs with neat options are not made for older engines, so stay away from plugs with gadgets. Standard old NGK B6ES is what I run on a street L motor down here at sea level. As you go up in altitude, you may want a different plug, but you definitely want to play with jetting first. Plug gap can absolutely affect fouling. If fouling, try running the gap tighter. Maybe .025" gap. Snap-shot taken from the interweb - Quote Link to comment
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