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| Looking for opinions / help reading spark plugs https://slantsix.org/forum/viewtopic.php?t=26435 |
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| Author: | 65deuce [ Sat Dec 29, 2007 1:24 pm ] |
| Post subject: | Looking for opinions / help reading spark plugs |
These are the plugs I fired the engine up with, they have about 1200 miles. From what I've read, I think these plugs indicate an over advanced timing condition, but what do they tell us about mixture or heat range. They are NGK ZFR5N's The shot with 3 are cyl. 1-3 and the close ones are cyl. 2 & 4. I guess regardless of the issues they reveal, I think it's good that they all look very consistant. Let's hear some opinions.    
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| Author: | SlantSixDan [ Sat Dec 29, 2007 1:28 pm ] |
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Mixture looks slightly lean. What about these indicates overly-advanced timing to you? |
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| Author: | 65deuce [ Sat Dec 29, 2007 1:31 pm ] |
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Well I thought that since the color change on the ground strap was so close to the body that meant too advanced, I was also under the assumption that the speckling was from preignition. |
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| Author: | SlantSixDan [ Sat Dec 29, 2007 1:56 pm ] |
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I wondered if that last photo showed metallic speckling, which would indicate pinging, but not necessarily overly-advanced timing — a lean mixture causes pinging, too. Can't think of a mechanism by which overly-advanced timing would affect the colour change point on the ground electrode, and have never read or heard of same. |
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| Author: | 65deuce [ Sat Dec 29, 2007 2:17 pm ] |
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I was searching the web recently and found a number of sites that refer to the coloration of the strap. http://www.4secondsflat.com/Spark_plug_reading.html |
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| Author: | SlantSixDan [ Sat Dec 29, 2007 2:26 pm ] |
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Interesting. First I've seen of it. Wonder if it's true. 
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| Author: | LUCKY13 [ Sat Dec 29, 2007 3:09 pm ] |
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That is detinating real bad, infact with a magnifyling glass and the right light you might even see some aluminum in thoughs black spots. My guess is that you may be runnning the vacume advance with a recurved dizzy and the ping is at part throttle high load. I know it goes against the grain but wiht a engine that has this much compression I would get away from those extended plugs and get a little colder heat range. When reading the plugs like this the fuel mix can effect those timing marks, and the timing can effect the fuel mix. The heat of the engine & intake manny also come into play. It really is a balancing act to get the plugs where you want them. There is a lot fo conflicking info on this subject but if you weed through it all yo will get a good understanding on what is going on. I have many other links I can supply to help but I dont have th etime right now to dig them all up becuase I am helping my son put his truck back together. I will come back later and try to help plus give some good reading links. You really need to be cutting the plugs apart to get real readings and you need to only run the plug ( a new plug for every test) for the part of the power curve you are testing if you dont have a wideband. I would love to see a pic of th eplugs cut apart. Take a little disk grinder and cut into the threads at the base of the plug. The housing will pull off and you can view the white part of the plug all the way to its bottom. This or/and a wideband is where you determan if its fuel you need to add, heat you need to take away, or timing you need to change to reach the results you are after. It can take a lot of plug, but it can be minimized with a little thought. By looking at your photo's I expect you have put a lot of time & money into your setup and would like to take the tuning to a higher level than most. It will pay off if you do but it will take a lot fo work & time & can drive you crazy before you reach the end. But its worth it. Jess |
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| Author: | 65deuce [ Sat Dec 29, 2007 3:22 pm ] |
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These are interesting revelations, since I put the car back together I've been dealing with a hot condition at highway speeds, and I beleive I do hear some pinging aroun 25-2800 rpms on the highway. What options are there in NGK's anyone....SSDan? |
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| Author: | LUCKY13 [ Sat Dec 29, 2007 4:16 pm ] |
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I just checked back in real quick and dont have much time, but if your running hot on the highway that is ussauly a good indication that you have a retricted water flow. It may be from the radiator ( stoped up or to small) or even a hose that collaspes when hot, or has alot of vacume pulled on it from a good pumping water pump. A spring in the bottom hose can cure this. You really should run your coolest at highway speeds. Even a loose water pump belt can cause a lack of flow if there is no restriction. But also to lean can cause it to run hot, or to low of timing. Or the water can flow to fast from to low a thremostat ( like a 160 that would stay open all the time) or no stat. Restriction, or to fast a water flow, will most of the time cause a slow incress in temp and keep climbing while at speed. As sooon as you slow down it cools back off. No matter what the cause, the heat of the engine should be fixed to run consistant before chasing a tune problem. The closer to the edge of a tune you get, the more small things can effect it. But also the better she runs when all is right. It will be late tonight before I can post the links, if i am not to warn out I will. If not I will get them the first thing in the morning. I wish I had a good camera to show the results of our tuning on the plugs with the steps we took for each condision. We have discused this but its hard to put the money out for such things even though we would like to help others learn what can be done. We have been quite surprized with our results and if we can find a dyno local we will atleast get a base pull of the power level of our stock engine. Kinda interested in the numbers ourself after seeing the performance we achived. I located three dyno's in the area today and will call monday to see if we can afford to test. For now I want be back until late tonight, or tomarrow. Jess |
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