Pablo Posted January 25, 2009 Share Posted January 25, 2009 Hi! On my racer the #2 and #5 cyls the plugs run richer, black residue on them not wet, while the rest are nice and light brown. the comp is good about 5 lbs apart from best to worse, valve adj is good. tried swapping plugs, wires, cap and rotor? I'm using two dome top SU's converted to electronic ign? any suggestions? could it be because those two are a strayter shot in the manifolds? Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 28, 2009 Share Posted January 28, 2009 sounds like a differance in flow. check for crushed header. Is there any work done to the head? If a head was ported and the flow from cylinder to cylinder is off it will cause AFR differances between cylinders. Quote Link to comment Share on other sites More sharing options...
Pablo Posted January 29, 2009 Author Share Posted January 29, 2009 Thanks jc. I didn't think of exhaust makes sense. The head is stock E-31, the header is an old motorsport auto 6 into 1 the car sat for a long time [years] with out running the was some rust inside and out cleaned must i could ran car 3 times this past year thats when I noticed the cylinders running slight richer than the rest. Guess we'll look into that. Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 30, 2009 Share Posted January 30, 2009 Thanks jc. I didn't think of exhaust makes sense. The head is stock E-31, the header is an old motorsport auto 6 into 1 the car sat for a long time [years] with out running the was some rust inside and out cleaned must i could ran car 3 times this past year thats when I noticed the cylinders running slight richer than the rest. Guess we'll look into that. This is a bit hard to understand. Try using punctuation! Also a weak spark in those cylinders could cause them to carbon up like that. I would replace plugs, wires and the cap and rotor at least. Quote Link to comment Share on other sites More sharing options...
naviathan Posted January 30, 2009 Share Posted January 30, 2009 Could be bad valve guide seals allowing a bit of oil in those cylinders. Quote Link to comment Share on other sites More sharing options...
Pablo Posted February 1, 2009 Author Share Posted February 1, 2009 Hi JC! Sorry about the puntuation, sometimes I go to fast and don't think about it. I get reminded about it when I E-mail my kids teachers. the cap, rotor and plugs were new, the wires are old Moroso Blue Max. Tryed swapping wires between cylinders but those stayed the same, they ohm out good. I'm gonna run it again in May hopefully. The eng. runs strong don't want to take it appart just for that. Is not that bad, they get powder black if they get worse then I'll have to. Naviathan! the head was gone over at a thrustworthy machine shop I hope they didn't miss that. But I didn't notice the plugs getting like that with the E-88 the only difference is the E-31 I put in the beggining of last year. Maybe there is something there? I need to do a clutch on it for sure. then I'll spend more time on this plug deal. Thanks for the replies guys. I'll post any updates. Don't hesitate to post any other suggestions. Thanks Pablo Quote Link to comment Share on other sites More sharing options...
jc052685 Posted February 2, 2009 Share Posted February 2, 2009 Well if it runs and your happy with it I would never tear the motor down for that. Quote Link to comment Share on other sites More sharing options...
naviathan Posted February 2, 2009 Share Posted February 2, 2009 If you think it's related to the head you put on, it could be the valve stem seals. If the guides haven't been changed they could be worn and despite good seals oil could be leaking from play in the valve stems movement. Did the shop check the head over, or did you have them actually do some machine work on it? Sometimes taking a head to a shop and asking them to look it over doesn't give them much incentive to actually put any effort to it. They may have checked the gasket surfaces and let it go at that. The only way to check the seals would be if they had removed the valve springs at a minimum. Quote Link to comment Share on other sites More sharing options...
Pablo Posted February 2, 2009 Author Share Posted February 2, 2009 They had the head completely appart, I assembled it. I think I just checked the guide by moving the valve side to side in the guide minimum play didn't actually took a measurement reading. The shop told me they were good, I've known the owner for many years good honest guy, now he has help which did the work, giving him the benifit of the dought till find the cause. also I put brand new factory valve springs, need to ck. if any are broken? Quote Link to comment Share on other sites More sharing options...
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