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EFV-8 Club Forum / General Ford Discussion / Fouled Spark Plugs

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Posted By Discussion Topic: Fouled Spark Plugs -- page: 1 2     carguy 07-16-2010 @ 6:42 PM reply profile send p.m. New Member Posts: 167 Joined: Oct 2009 When I install new plugs the engine (original '34) runs well but they too soon get fouled and the engine starts to run poorly with a significant loss of power. I have had the coil, distributor, & carb repaired and new plug wires. The compression seems OK at 110 - 120 for each cylinder. I have not yet removed the intake or heads. Before I start tearing into the engine is there something else I should do? Pauls39 07-16-2010 @ 7:13 PM reply profile send p.m. Member Posts: 81 Joined: Oct 2009 Hook up a good vacuum gage and see what it will tell you. The points may be worn or the timing retarded. The exhaust may be partially plugged. The valves may be worn or out of adjustment. Your carburator may need adjustment. Use the gage to pinpoint problems before you start tearing the motor apart. You might try disconecting one plug wire at a time listening for a drop in RPM. If there is no decrease, that cylindar is not doing its job. Rebuilding an engine because the distributor or carburator is faulty, is expensive and largely a waste of time. supereal 07-17-2010 @ 9:19 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Are you adding anything to the gas? Constant use of Marvel oil, or other additive, will foul plugs eventually. It is a good product to use occasionally when a sticking valve is suspected, but adding it constantly to fuel as a preventative measure is asking for trouble. That is why the highly advertised automatic "upper lube" oiler accessories went out of style years ago. We still see them at swap meets, and I've been told they are being made again. TomO 07-17-2010 @ 9:45 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Plugs can become fouled due to too much idling or low speed driving, not driving the car long enough for the engine to reach operating temperatures, weak spark, oil leakage past rings,etc. Here is a link to photos of spark plug conditions and causes. Compare your plugs to one of the photos and if you have any further questions, come back here for answers. http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm Tom 37RAGTOPMAN 07-17-2010 @ 2:09 PM reply profile send p.m. Senior Posts: 1961 Joined: Oct 2009 how old is the gas,? this stuff they sell today gets old fast,and will create problems, also try running the engine without a aircleaner, or a different one and see if that may be the problem..a dirty or clogged air cleaner is like running with the choke on,and will foul the plugs, see if you are getting a strong blue spark out of the distributer,and make sure the condensor is grounded and tight, with a mirror and a flash light, with aircleaner off look down though the carb and see if it is dripping gas, does the exhaust blow black smoke out the back while running,? let hear how you made out, 37 RAGTOPMAN and KEEP ON TRUCKIN,,!!! carguy 07-21-2010 @ 7:54 AM reply profile send p.m. New Member Posts: 167 Joined: Oct 2009 I havn't yet tried all of the suggestions but I did compare the spark plugs I recently pulled with a set that I pulled a year ago. The interesting thing to me is that the fouling is not uniform, running from normal to dry fouled to heavy soot, and that the recent set of plugs look almost exactly like, cylinder by cylinder, the plugs I pulled a year ago. Both sets of plugs are Champion D16. And, I don't have very many miles of use in the last year. supereal 07-21-2010 @ 9:38 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 As you have covered most of the tests, compression, etc, and replaced the plug wires, finding the cause of a rich mixture is likely in the fuel system. It could be a partially clogged air filter, a misadjusted choke that is not opening or closing fully, or the now common problem of a leaky power valve gasket. Even though you had the carb repaired, that doesn't mean it is OK. The replacement power valves have a rounded shank, allowing incomplete sealing. Remove the carb, set it on the bench, and with the bowl full of fuel. leave it to stand overnight. That will tell you if there is leakage that otherwise can't be detected. With the compression reading you quote, tearing down the engine isn't likely to do much except cost time and money. Pauls39 07-21-2010 @ 9:50 AM reply profile send p.m. Member Posts: 81 Joined: Oct 2009 What did the vacuum gage/test show? Is your carburator a 97 or 94? That will make a difference in the type of power valve you have. You may have a leak in the intake manifold which would account for some of the plugs being darker than others. A sticking intake valve could also upset the mixture on other valves. Run some tests and let us know. sturgis 39 07-24-2010 @ 3:00 AM reply profile send p.m. Member Posts: 74 Joined: Nov 2009 GO TO A HOTTER PLUG.I HAVE NOT HAD GOOD LUCK WITH CHAMPION PLUGS. I WENT TO SMALLER JETS AND NKG PLUGS WITH EXTENDED ELECTRODES.THE PLUGS LAST ABOUT A YEAR NOW. This message was edited by sturgis 39 on 7-24-10 @ 3:09 AM 1934 Ford 07-24-2010 @ 8:19 AM reply profile send p.m. Senior Posts: 573 Joined: Oct 2009 I gave up on the champion D-16 and switched to the Autolite 386. Much cleaner running plug and better looking too. Cost $1.44 each at Advance Auto Parts when on sale.

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