Corzette Posted November 15, 2003 Share Posted November 15, 2003 I am running rich and the plugs are kinda black. Do I run a size or two colder or hotter plug to help with this? What is the proper thinking of the two. I know I have the jet issue but I have already come down significantly and its still rich. Would the plug change help? Should I change my gap? Imat 43 now with MSD.... CZ Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted November 15, 2003 Share Posted November 15, 2003 I believe cold helps slightly with a rich condition and hot helps slightly with a lean condition. It doesnt help so much with any burning or producing any power, it just helps make sure that the spark plug fires. I'd check the AFM and timing as well. Oh ya, and if all else fails and you are still running too rich, just get some more air in there to make the fuel burn! Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 15, 2003 Author Share Posted November 15, 2003 Im running 16 advance or so at idle and my idle screws are about 3/4 a turn on four corners. I have a 750 DP now with 69/76 jets. Used to be 71/80. Maybe I can come down in the rear a little more... Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted November 15, 2003 Share Posted November 15, 2003 Get one of those color plugs to check your AFM. Those double-guzzlers are known to suck a lot of fuel until you get them tuned just right. Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 15, 2003 Author Share Posted November 15, 2003 Oh yeah, how would gap affect this...closer/wider? Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted November 15, 2003 Share Posted November 15, 2003 This is starting to look like a chat session Gap isnt going to make much of a difference, if you are running too rich there isnt going to be anything you can do to get more fuel to burn. Fuel, of course, needs air to burn. Any changes to the plugs are going to be simply to make sure that the spark plug keeps firing and you dont get any misses due to the richness. A closer gap will help make sure that the spark plug fires, but will only hurt performance if it is not having any trouble firing at the gap that it is at now. Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 15, 2003 Author Share Posted November 15, 2003 Thanks...good to chat with ya! Im going to the Zone and get 1 step colder plug and come down to 72s on the secondaries and see what happens..... CZ Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted November 15, 2003 Share Posted November 15, 2003 Hi corZette... The reason your plugs are black is they are covered with unburned hydroCARBONs. A hotter plug will help burn this off, but you really need to get your engines air fuel ratio tuned. Once you get that set, you can play with heat ranges. (I like NGK plugs as they seem to have a broader heat range than the other brands I've tried. YMMV). If a person has a stock engine that burns oil (fouls plugs), going up a range or two from the known factory spec. plug is a relatively easy call. With a modified engine one must make an emperical determination as to the proper heat range after the AFR is known to be correct. I'd say a dyno day is in order. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 16, 2003 Share Posted November 16, 2003 yeah dude you want hotter plugs to burn off the black soot, colder plugs only gonna make it worse. It's only covering up the problem though. Well and yeah it is good to have it so that they burn off the soot so that you dont start having misfire problems. Colder plugs are good if your plugs are glazing, which is basically when the deposits on them melt, or if you're having problems with detonation, it can sometimes help that too. Also if your motor diesels. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted November 16, 2003 Share Posted November 16, 2003 Thanks...good to chat with ya! Im going to the Zone and get 1 step colder plug and come down to 72s on the secondaries and see what happens..... CZ Your carb set-up may be the overrich problem. Before I turboed it, my Z had a 383 with a 750 Double Pumper. The carb came stock with 70 primaries and 80 secondaries. Champion RC12YZ plugs ran clean at .035 gap. Is your float level correct, powervalve not ruptured, and idle screws adjusted to highest vacuum setting? My carb is 20 years old and naturally aspirated my Z ran 11.15 at 123 mph, with that setting. Turbo Meister Quote Link to comment Share on other sites More sharing options...
Tim240z Posted November 16, 2003 Share Posted November 16, 2003 As said above, you can't tune your fuel/air ratio with plugs. Tune the carby first Tim Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 16, 2003 Author Share Posted November 16, 2003 Thanks guys..yeah I tuned the idle AFM already and its decent. My original jets were 71/80. I now have 69/76. I also find it next to impossible to cross reference the next hotter plug. I am running NGK BCPR5ES now. I know I need to bump it up but should I try one step hotter or two? Your right I do have the black soot a little but the electrode is tan.... your move... CZ Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 16, 2003 Author Share Posted November 16, 2003 By the way, power valve is new 6.5, vacuum is around 12 to 13 hcg. I have the 750DP, but my gap is at .043. Should I run .035 with the MSD 6A? The float level is good, barely trickles out a little when you take out the plug. Idle screws are good....Aluminum Heads AFR190s. CZ Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 16, 2003 Author Share Posted November 16, 2003 Another find....the NGK plugs get hotter the lower the number. AC Delco is the opposite. NGK goes from 2 (hottest) to 14 (coldest). Mine is BCPR5ES-11 so I think I will try the BCPR4ES-11 and see. Thats only two steps away from the hottest plug. I will lower the gap to .035 as well and recheck. CZ Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted November 16, 2003 Share Posted November 16, 2003 If I had your car I'd run it as it is. If you develop a misfire problem, then consider a hotter plug/narrower gap. If the electrodes are tan, they are close enough to run... they may get a little warmer when you hit the highway, and going hot enough to get a bone white electrode is, IMO, not good... If the MSD is firing the wider gaps, why mess with them? I think that Detroit went to higher voltages and wider gaps to better fire lean mixtures (which you don't have) but I see no harm in lighting off a little more mixture. You'd have to do some research or ask Grumpyvette for a definitive answer. Quote Link to comment Share on other sites More sharing options...
Corzette Posted November 16, 2003 Author Share Posted November 16, 2003 Roger that , I am concerned wit the black soot that is collecting around the bottom of the plug. Im gonna see what the NGK BCPR4ES will do. I have the 5s now. Oh I meant the 4202 Bosch Platinums. They are the same as the 4ES's. My car will make your eyes water and I think I need to dyno it, but I remember that some on the board picked up quite a bit of torqe and HP etc by de-Jetting from a real rich condition. Thanks for the advice, I can always put the NGK 5ES plugs back in if it doesnt work out. CZ Quote Link to comment Share on other sites More sharing options...
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