Please see pic of my carbon-fouled spark plugs just taken out today. This is a dry, sooty carbon and not wet appearing to the eye or to touch although I do smell fuel/ gases from the engine compartment. It fouled these pretty quick and they are the Champion RV17RC's gapped at .035. Just prior to that, it also fouled a set of Motorcraft plugs recommended by John Osborne and gapped at his recommendation of .045. Plug fouling has long been a problem with this car! Carb was just redone/ rebuilt totally for my combo by John Osborne and is a 7040240 Q-Jet. Hasn't been driven hardly at all since getting the carb back less than a month ago. Ignition is an old, antiquated Singer S-4 set up with a modified points-type distributor with Stinger internals. Car is timed appropriately I think? What else could it be? Notice too, the carbon that came out of the tail pipes beside the box with plugs. An equal amount of carbon was on the left/ driver's bank too. Any and all help would be appreciated. I'm really getting frustrated with this car and can't use or enjoy it with all the problems it constantly throws my way. I've also through more than a fair share of $$ at it and that's getting old too. I really hope you guys can come through for me. I have a few more pics of the plugs if needed but they all pretty much look about the same as to fouling.
Here are a couple of good websites to read up on this: http://www.sentra.net/tech/sparkplugs.php http://www.gnttype.org/techarea/engine/plugs.html It sounds as though you're burning oil. It may be the engine is due for a ring job or the valve stem seals are shot. Just my .02.
Ouch.... those would be expensive repairs! Sure hope it's not one of them. Haven't noted any excessive oil consumption on engine. Heads with new valves, seats, and seals have been freshened within last two years with less than 3000 miles on them. Motor was rebuilt about 10-12 years ago but only has about 20,000 miles total on it since the rebuild. Cam, lifters, and pushrods (adj) were changed last year. Thanks for the input. Those links do provide some good info!
OK, now that we have some more info, I would definitely do a compression check and see what kind of cylinder pressure you're generating at all 8. You can get a compression indicator at Autozone for about $35. Each engine will be different because of the cam and it's properties. Which cam are you running and what are it's specs? Also, what is your engine's compression ratio? I think you'd want to see a good 160-180 lbs. or so, depending on your cam. My engine personally was at 205-210 lbs. on all cylinders with Poston's 113A cam, but I also used file fit rings for little leakdown. Next, as recommended by others, check your fuel pressure and see if you've got 6-7 lbs.
What cam is in the motor, and was there an excessive period of idleing right before these plugs were pulled out? Are there any other indications of problems.. (hard start, run on, spark knock or poor performance) JW
Cam is a Poston GS112-A which is a mild cam slightly hotter than a stock Stage 1 cam they state. Got a cam card somewhere but don't know specs by heart? Don't know what CR is for this engine either?o No: I can prolly borrow a compression tester from a friend early next week and will check that. As far as measuring FP, how do I do that with a carbed car? I know how to with my SFI Turbo Buick and have a mechanical test n tune gauge that connects at fuel rail. I also have a Stage 1 mechanical fuel pump on the GS. I think that addresses questions right now. I'll check back in alittle later. We're on the old dial up system and don't want to tie up lines all afternoon. Thanks for all your help.
Jim, Yes, lots of idleing before motor was pulled. Pretty much all of the time on those plugs pictured was on either on idle or in driveway. With all of the probs with this car, I'm really leary about getting out and getting stranded! Major mistrust factor if you know what I mean! Haven't noticed any of the indicators you asked about Jim. I can say that the car has never ran like I feel that it should but has been stronger after getting carb back from JO.
I was thinking of that too now. Maybe you don't have a good hot spark any more and sitting there idling you're not getting complete combustion. Have you tried "blowing the carbon" off the car getting on the highway at all?
Wow Evans!, I never realized your fouling problem was that bad. The only two things I know of that will cause fouling like that are overly rich fuel jetting or weak ignition. The carb has been rebuilt by John Osborne, so I know it is right. I would suspect your Stinger is not supplying a hot enough spark anymore, for whatever reason. If I was you, I would get an MSD 6A or 6AL, and trigger it with the Stinger distributor. The MSD box is really easy to install, and all you need to use your Stinger distributor is an MSD connector part # 8824(available from Jegs or Summit) You simply clip off the Stinger connector, and solder on the MSD connector. The hardest part is getting the polarity right. If you wire it backwards, the engine will run very advanced, just reverse the leads. With the MSD, you won't foul plugs, it generates alot of multiple sparks at idle. Have you ever adjusted your idle mixture? When I got my John Osborne Carb back, I found the idle mixture needles turned out way too much for my engine. Just a thought. Hope that helps.
My hunch and intuition on this problem kept me thinking that it MIGHT be ignition- related. Suppose it may be time to ditch that old Stinger box and step up to an MSD 6 or 6AL box. Thanks Larry for the reference on the harness plug needed to make that work with the Stinger distributor. I don't have one (MSD) to borrow- would the general consensus be that the old Stinger unit probably isn't creating enough spark? Any other different opinions or like ones? Thanks for all the help everyone.
How about maybe a weak coil in addition to an old ignition box? Are your connections tight on everything? Any corrosion on any of the ignition connectors? Seems a shame to keep an old coil when going to a new ignition box, particularly when the technology has improved.
Coil is new- Borg Warner unit from NAPA less than 3 months old. I'll check for corrosion on any ignition connectors. Connections are tight I believe but will recheck tomorrow. Thanks for the insight!
Evans, I chucked my Stinger because it was intermittently misfiring up on top end. MSD is the way to go. I love my Digital6, it will fire anything. I'm running a .050 gap with no problems. I guarantee it won't let those plugs foul. The MSD 8200 made in USA coil is the one to use.
I think your Stinger S-4 has given up the ghost.The Stinger over time has a problem with it's grounding, and shorts out resulting in poor spark operation. A friend of mine had an old Stinger and his plugs looked exactly like yours.He now runs an MSD and hasn't had any problems whatsoever. I agree with Larry,get yourself a MSD digital 6.
Evans, Have you checked the idle mixture? With the engine running, pull off a full vacuum line. If the engine speeds up alot, your idle mixture is overly rich. Idling an engine like that with the Stinger will foul those plugs. The engine idle system adds fuel even at part and full throttle. Something to consider.
OK, befrore we all go nuts and start ripping stuff off the engine, Tell me about the carbon, please, Dry and dull, sooty? Slightly shiny, wet? Dry and dull, sooty, too rich. Float level, liquid level in float chamber too high, idle stopped throttle plates too far open, air correctors blocked/dirty/wrong size (too small), idle fuel orifaces in the base plate modified too large, decreasing sensitivity and altering flow volume control. Slightly shiny, wet, oil. Oil that is present in the exhaust at fireup only, with clean plugs designates leaky exhaust valve/guides, loading oil onto valve heads in the exhaust ports, burning same on fireup only. Wet oily indicates intake valve/guide issues, leaky oil control rings (although with this, you should also have a fog screen of smoke following the car as you drive), leaky inlet gaskets, wrong weighting of the PCV system (wrong valve), bad venting of the crankcase giving too much pressure, anything the vacuum the engine makes that can pull oil/oil vapor into the inlet system. Will smoke white smoke for a fair amount of time after startup, even when at ops temps, not just cold. I'd say that then issues weren't ignition related, but fuel, too much of it at idle, leakage and possibly, exhaust flow being restricted, a possiblilty. I'm really leaning twords the carb, though, unless the Stinger system has failed completely. Does the Stinger work at higher rpms? If so, I'd figure it wasn't the Stinger making trouble. BTW, Stinger plug gaps, .035 max. With 8 to 15 initial degrees of initial timing, where it should be, even with a lowly no volts points system, there shouldn't be that kind of richness. Since the Stinger gives about 18,000 volts at the plugs, it is at least twice as powerful as a points system, shouldn't be an issue. Engine temps need to be 180 degrees, lower will make the combustion process inefficient, and require richer fuel volume, sooting the plugs up. At this point, I'd go with two tests, compression and leakdown. When you do the compression test, two things should be done, disable the ignition system, and block the carb wide open. Just remember to take the block off the throttle before you attempt to restart the engine, or...you'll have your own version of a 'Brick-Out". Next, leakdown test, and you do need one.
