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Old 07-29-2006, 12:29 AM
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rich or lean

hi hows it going i have probably a stupid question how do u know if your car is running rich or lean i recently put a new cam and carb on my vehicle also put new plugs and wires on but have a miss from 1700 rpm to 2100 rpms i am not sure if it is an electrical problem or fuel problem i pulled my plugs and cant get a reading yet

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Old 07-30-2006, 07:51 AM
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there are a lot of indicators Black smoke on acceleration= rich. Inside of pipe white=lean. Spark plugs white=lean. Spark plugs black= rich. plugs should be a nice dark tan. running hot=lean and the list goes on and on. The best way? Find someone with an exhaust gas analyzer and have them test it.
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Old 07-30-2006, 08:22 AM
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Quote:
Originally Posted by 61bone
there are a lot of indicators Black smoke on acceleration= rich. Inside of pipe white=lean. Spark plugs white=lean. Spark plugs black= rich. plugs should be a nice dark tan. running hot=lean and the list goes on and on. The best way? Find someone with an exhaust gas analyzer and have them test it.
Ditto. Doesn't get any better than reading your plugs. I'd skip the anal-yzer and just learn to read your plugs. Inside every Chilton's manual, there is a nice color photo chart that explains it in perfect detail. Learn to read your plugs, and you'll never be at a loss for what your car is doing.
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Old 07-31-2006, 02:24 PM
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The miss

Is your dizzy cap new?
Sometimes there could be a small hair line crack in your cap, it will track out a ground if the conditions are correct. At certain rpms, there is enough energy released from the coil that will cause yous cap to ground out and cause the miss. Then are your wires new? Wires can get weak at certain spots if they are left against the engine for a long period of time. The insulation brakes down and creats a weak spot, or may it pe called a soft spot in the insulation, which in turn will lead to an arching and short in the plug wires. You can test this by being in a dark garage, crank up the engine a nd set it up to around the miss rpm and watch for archs jumping across your wires to the block. Your carburetor flot adjustment could be off and at that range of rpm, your float fails, thus your engine is starving for fuel. Or your if you have a mechanical fuel pump, it could also be the weak link and has a small diaphram hole, which stumbles and pushes air into the fuel flow.
There are several small but significant gremlins which would give you the problem. Make a check list, balance it against your Hayes or Chiltons trouble shooting section, and do like the rest of us are prone to do. It is time consumming and does lead to partial break downs in the mental aspect of things. Have some local gearheads over and make it an evening project with a cook out and some good drinks. It does take time and patience.
Don't pull out too much hair in the quest of the great miss! LOL
Good luck.
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Old 08-01-2006, 10:04 PM
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thank you guys for your help i know reading your plugs is a crucial thing to be able to do. i am totally color blind so it makes it kind of difficult to read but have had a rodder neighbor of mine read them and says they look good but still have that break up. i have changed the plugs, wires, cap, rotor, checked fuel pressure, changed metering rods and springs, jets in the carb, even the carb itself (was an edelbrock 600 so i changed to a 750 edelbrock). i also checked play in the distributor and the stator for looseness, replaced advance springs etc. everything i can think of i am at a total loss. it sounds electrical and now has progressed to happening at higher rpms under a heavy load i run the flashlight drags in this area and when i get to 4500 to 5000 it will break up but real quick then straighten out. to give a little more insight as to what i am running i have a chevy 350 .030 over, vortech heads (guides cut down for large lift cams), matching gm performance intake, lunati voodoo camshaft, lifters, springs (all matching) lift is 504/525e - 233/241e duration @.050 also has a 110 seperation, roller rockers with a 1.6 ratio, new msd 6aL ignition box, accel plugs, cap, rotor, and wires, the fuel pump is also a holley mechanical pump rated at 110 gph regulated at 5 psi, timing set at 44 degrees total advance and use no vacuum advance. headers are wrapped as to protect plug wires and starter. holding 10 hg of vacuum at an idle.if you sit there and hold the engine at 1800 rpms u can hear the miss slightly and if you goose it from an idle it will stumble (just like a plug is weak or failed)for half a second then will smooth right out and now when making a run it breaks up real quick at somewhere around 4000 or 4500 rpms most noticable when heavy load is on it or trying to cruise through town at a low rpm. the rest of the time runs real strong. ( have already put 2 sets of plugs in with no change) like i said i am lost.
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Old 08-06-2006, 04:27 AM
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I have a question along the same lines regarding the sparkplugs, so the top of the electrode is white, but the ring around the bottom is sooty black
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Old 08-06-2006, 12:45 PM
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Your running 44 degrees of advance with Vortec heads? That is way, way, way too much timing. Timing should be a total of 32.

A miss like your experiencing is either:
A) ignition
B) a very, very lean condition
c) bad camshaft
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Old 08-06-2006, 12:50 PM
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Quote:
Originally Posted by Ortie666
I have a question along the same lines regarding the sparkplugs, so the top of the electrode is white, but the ring around the bottom is sooty black
The sooty black means your rich.
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Old 08-06-2006, 01:54 PM
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Quote:
Originally Posted by Rick WI
The sooty black means your rich.
Ok, but the top of the sparkplug is bright white?? there is a jacobs electronic ignition in it, i went to one step colder plug already,
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Old 08-06-2006, 03:55 PM
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What you want is an indication of what the combustion chamber is burning like. The part of the plug that will give you that indication is at the base of the threads. We can run 9:1 air fuel ratio on our 1200 HP nitrous motor and still have a white plug like yours with a super cold 10 NGK.
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Old 08-06-2006, 06:15 PM
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OK and when i it accelerates threw the primarys but it feels like asoon as it hits the secondarys it starts crackling but not poping and banging threw the pipes not the carb, too rich??
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Old 08-06-2006, 07:48 PM
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Ortie, it's impossible for me to decipher what the sound is your talking about. I just don't know. The plugs though tell the tale, and soot where your describing tells me it's rich.

The safe way to diagnose is to set what the jets are in the secondaries and install two sizes bigger, if it's worse it's rich. If your not sure it's always best to er on the safe side.
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