Pmaenner Posted September 24, 2022 Report Share Posted September 24, 2022 Hi everyone, Got a dumb question I need answered. I recently added in a cold air intake on my R1 avanti, before that it was breathing from the oilpan. I'm trying to re-tune the engine. I know how to make carb adjustments, but have been getting conflicting info on reading spark plugs. How long does the car need to run before reading plugs? Also, do I need a new set of plugs for every reading? I've heard people say 1/4 mile and 200 miles, and I've heard you can and cannot re-use plugs. Lastly, is there a preferred plug to read or do you have to read all of them? Thanks for the info! Link to comment Share on other sites More sharing options...
64studeavanti Posted September 24, 2022 Report Share Posted September 24, 2022 The "breathing from the oil pan" is part of the PCV system. Link to comment Share on other sites More sharing options...
Pmaenner Posted September 25, 2022 Author Report Share Posted September 25, 2022 But that was the only air intake to the engine. I have an enclosed air housing, and the the only intake was 3/4" hose from the oil pan to the air cleaner. I kept the the 3/4" air hose to the cleaner, but added a snorkel and 3" air hose to get in fresh air as well. So, in regards to the first question, what is the procedure to read plugs? I think I am running lean and want to get an accurate reading before I make any adjustments. Link to comment Share on other sites More sharing options...
64studeavanti Posted September 25, 2022 Report Share Posted September 25, 2022 If you have the stock air cleaner, the engine gets air via the gap between the base plate and cover. That air goes through the filter into the carb. The air hose from the oil pan is the part of the PCV system that scavenges crankcase gasses. This is very similar to PCV systems on other makes and years. The other part of the PCV system is a much smaller hose that connects to a valve at the base of the carb. All very well engineered. Adding additional fresh air to the system does no harm as the engine will only use as much as it needs. Link to comment Share on other sites More sharing options...
Leo B Posted September 25, 2022 Report Share Posted September 25, 2022 (edited) In older engines and racing engines, the breath is not directed back from oilpan or valve cover to the combustion chamber/carburetor. The crankcases and covers breathe directly out through their own filters. Racing cars want as clean and oxygen-rich air as possible into the combustion chamber. But in our standard cars, the different is not so urgent. So keep it like it is. Works like 64studeavanti wrote. You can only read rough values from the plug regardless of whether the mixture is too rich or too lean. Today's fuel no longer gives coffee brown color. Test plugs are available with which the richness of the fuel can be adjusted reasonably well. Search on google: Gunson Colortune Spark Plug Tester. But this way the problem will be youll find that one cylinder is richer or leaner than the other and endless tuning with eights plugs. Good tool in one or two cylinder engine (motorcycle). You need best total solution. The best way to find the correct adjustment (do it yourself) is https://actron.com/content/engine-performance-testing-vacuum-gauge These are the things I have learned. If anyone can add or correct, please let me know. Edited September 25, 2022 by Leo B Link to comment Share on other sites More sharing options...
Pmaenner Posted September 25, 2022 Author Report Share Posted September 25, 2022 Ah, never noticed that gap, its pretty small. I thought colder air was better than hotter air for an engine, do the studebakers like hotter air? Right now the plugs are bright white, last time I checked they were light tan, so I think I am running lean. How long do you drive it around before checking? Thanks for the tips! Link to comment Share on other sites More sharing options...
Leo B Posted September 25, 2022 Report Share Posted September 25, 2022 (edited) How long? Time and distance are not important. Drive with warm/hot engine using avarage driving speed and normal engine load. Stop and turn off the engine (less idle the better). Light tan or brown is nice. Some plugs will be lighter and some darker. This is normal. About crankcase ventilation... Please read Workshop Manual / Engine page 5 and 6. Dont do any changes. Please check this article https://www.championautoparts.com/Parts-Matter/automotive-repair-and-maintenance/how-to-read-spark-plugs.html Edited September 25, 2022 by Leo B Link to comment Share on other sites More sharing options...
Pmaenner Posted September 25, 2022 Author Report Share Posted September 25, 2022 The colortune looks pretty cool, but I don't know how you would read it when driving the car to see how wot or part throttle looks. Link to comment Share on other sites More sharing options...
Leo B Posted September 25, 2022 Report Share Posted September 25, 2022 (edited) 2 hours ago, Pmaenner said: The colortune looks pretty cool, but I don't know how you would read it when driving the car to see how wot or part throttle looks. More Edited September 25, 2022 by Leo B Link to comment Share on other sites More sharing options...
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