These plugs started out pretty black the last time I checked them, street driving and a tunnel ram. They seem to be cleaning up with the 4 1/8 mile blasts at the track. I was expecting to see a much richer plug when I pulled them but not to sure I want to change jets now. They all are a dark gray color, not coffee mocha tan though. Sorry for the cell phone photo, not the clearest but what we got to work with.
Just to be sure what fuel are you running and what heat range are the plugs and the gap? Nice Dark Caramel/Mocha brown is what you are looking for like you stated. Yours look a little lean for gas. At idle and a Tunnel Ram it's probably loading up, high RPM dragblasts will allow the Tunnel Ram to start working and no pooling of the gas due to it getting the speed and atomization for flow it needs. Richen it up a little and see if the color changes on the strip, Or lean it out for more mellow street driving to get rid of the fouled plugs and the load up condition. Remember to fatten it up though before you burn a piston when you go to a high RPM situation. Tunnel Rams are tricky. Tim
I am going to go out on a limb here and say from what I see here that you are running a little lean. If they were sooty and all you made was 4 half p***es you should not be that clean and they are not a good color in the pics. The only real way to read them by the way is to run them at the RPM you want to turn, then shut the motor off and get it into neutral at the same time.
You probably already know that the only meaningful plug reading can only be achieved at the end of a WOT pull. Driving back to the pits or idling will change the reading. Also its hard to get color on (non-lead) pump gas. Street driving throws in a bunch more variables. Here are a two "experts" views and they don't always agree: http://www.4secondsflat.com/Spark_plug_reading.html http://www.angelfire.com/fl4/pontiacdude428/Readplugs.html
I agree with shutting the engine down right after the p*** and pulling a plug, but lets read what I got. The plug is a NGK replacement for the Champion RC12YC and gapped at 37, MSD 6al, MSD distributor and coil. Oh yeah 93 octane pump gas.
We can only ball park you with what you've got. you really need to be able to look way down in the bottom of the insulater as a rule and should start with fresh plugs. But like I said from the looks of things you are running a little lean. A little fat is always easier on the engine than a little lean. The operative word here being "little".
Pics are not that great. I notice a few of the ground straps are white looking. Looks a little lean too. How much timing are you running?
Swade, Let me ask you this, how many jet sizes did you drop, can you go in between what you had and what you have? If you can do that and run it again, maybe start with fresh plugs you can always keep those for spares. By the way you should be able to gap your plugs around .044 with the ignition maybe wider than that.
I got a set of fresh plugs in the box and the jets are jetted stock at 58's. These are the 450 cfm Holley tunnel ram carbs by the way.
Phil, I'm glad I took the time to read both " experts " view on plug reading. My advice is to read anglefires section where he addresses the " fire ring ". This is key, and why we as engine builders and tuners spend time deep down inside the plug with the illuminated magnifier/viewer. Of course you collect information from the center electrode, ground strap, thread base, and to a degree the porcelin. The porcelin is tricky because its very easy to get a false reading or a reading that was washed during the plug " chop ". Remember, be very careful with a large gap if your running domes!! I might even tighten the gap up, not open it up we are not trying to meet emisions here. I don't know enough about your new build to say at this point, TR
Phil, invest a few dollars in a index washer kit and play around with indexing the ground strap location, if you don't know how we can walk you through it. If you have aluminum heads don't forget a little anti-seize on those threads, TR
Much better pics now They actually look better in the new pics. Have you looked at the jets yet? Do they have three numbers on them one of the numbers being upside down? Like a 58 and then a 2 upside down? Good tips from Traditions Racing on the indexing. You can see from the pics that the plugs are all different directions. Some ground straps white while others are black.
TR it's the same as the last only forged rods/pistons and 30 over Yup got it on there and all over my fingers taking the plugs out..lol Right about a number after the 58 that kinda looks like an S or the upside down 2
The next richer jet is a 58 with an upside down 3. Each jet size come in three ranges. 1,2 and 3. These numbers are always upside down after the jet size.
Swade41 Do you have secondary meteering plates or metering blocks. IE can you change secondary jets or do you have to change the plate. If you have metering plates it would be worth your while to either go to a metering block or get yourself a set of cheater plates that you can screw jets into. You need to be able to control the jetting after the secondaries come open. You can do that by changing the metering plates (I have a chart for plate numbers somewhere) or simpler to set it up with jets. A cheater plate won't cost you any more than another metering plate. Just a thought. On a side note I cringe every time I call you swade, I spent some time in the south way back when.
Yup 4160 style carbs with a metering plate, not much room between carbs as it is. These are the old 600 cfm's in this picture but fit the same as the 450's. I'll start looking around for the next step up in jets here.
Well I went up from the 58's to 60's and changed the power valves down to a 3.5. The ET picked up from a best of 7.41 @ 91.91 mph to a 7.27 @ 93.57 mph. The plugs actually look pretty close to the same with only the #1 cylinder with a touch of mocha color on it. I might need to step up again, I'll try and get photos up soon.
new photos, they actually seem to have a bit more color in the photos and I had increased the gap to 45
Are they cast iron heads? Those plugs are for aluminum heads and they are not race plugs. If you have aluminum heads i would use ngk5671-8; cast iron head 5673-8 - they are colder than what you have and they don't have a projected tip. Get some race gas into the engine, the pump gas has too many chemicals. I am not sure the effect but i can't get a read on your plugs and i suspect that is why. They are just too contaminated and that might be the addi***ves in the pump gas. there isn't any indication of timing, you have msd and it is powerful enough so that we should read the timing on the ground strap - it just isn't visible and i don't know why. The plugs i read have much higher compression and maybe that is why i can't make sense of yours - here is what i would expect to see. The plug should come out of the engine and be bone dry, the flat of the threads around the top of the metal caseing should be light gray with a tinge of tan from the octane (lead) in the fuel; on the ground strap there will be 2 colors with a blueish line seperating the color, that blueish line is set by the amount of timing and it should be located about halfway in the bend of the strap, too far forward not enough timing and the plug is firing on top of the piston; in general the plug should look like it came straight out of the box. In a proper race engine with high compression and run under a heavy load at high rpm there is nothing going on inside the combustion chamber that will discolor the plug. The plug gets color from contamination, be it overly rich or oil or too much octane or weak ignition. Most people prefer to run a tad rich as they feel it is safer.
I thought they must be aluminum, it is such a traditional engine that i had to ask. I would try some low octane race gas, cam 2 purple maybe and see what happens. If you look close at the 2nd pic, plugs #7 & 5 you can see the timing mark trying to form - there just isn't enough heat/pressure in the cylinder to make it very distinctive. from what i can see there isn't enough timing - but taht is open to interpretation because the cylinder pressure is low and that might be due to too much fuel as well. Anyway, the timing marks on the ground strap is what i look for; the other biggie is cylinder heat and you read that on the threads. The top 3 threads should be nice and dry if a slighly different color, nothing dramatic, it is an indication of how much heat/pressure is in that hole.
There's a station in town selling 91 octane non ethanol gas, I just don't see the sense in running high octane race gas in this combo. I understand the want to see the race gas used to get a good reading though. Does bumping the timing up two degrees to 38 and not increasing the jets make sense or up the jets again ?
The carb mixes the air and fuel, atomizes it into a mist. Streeting a TR tends to break that vital chain- the longer those two are in the tunnel, and the slower they go with more bends, the greater the propensity for seperation. Add a fat plenum and you get pooling at low velocity. So folks usually do two things. Carry xtra plugs and hope the cool factor dont wash down the rings or lean it out then burn a crown @ the track. Reading junk pump gas on plugs is pretty futile. Unless you like 3 shades. Black, pink or speckled. Cranking more timing in on the threshold of stoichiometrics = burned crowns blah blah blah. You have a low-compression engine with a designed-for high-compression/WFO racing induction system on it. Short of spending time at the track under controlled conditions (sniffing the exhaust as it leaves the port is best, next is WFO, chop/kill/stab clutch @ the same time hoping you don't pull over on the vacuum or hit the wall), recording every little detail yer not gona see much other than the obvious pulling a plug run on pump gas with this combo. Ideally you'd have two set's of carbs and tune-up's. On the track who cares, yer in the slow speed circuits once then it's WFO put on the big guns. Street, smaller is WAY better on a streeted TR/10:1 motor- try and limit your lugging/lumping around and tune it for good tip in and WFO. Short of that for street cross-mount the carbs and go down to the smallest ones you can find. Most low compression combo's w/ overlaped sticks are way over carbed anyways ( flame on! ).
Well I went up to 37 shooters and a 63 jet and the car lost a tenth and a half mph. Back the other way...lol
Just pulled the plugs and the front 4 are darker than the rear, must be the way the tunnel ram is working. I might try and change the jets in the front carb only and see if I can get an even color of plugs all the way around.
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