OK, I've got this gauge, it uses a thermocouple washer, goes on the plug instead a regular spark plug washer. a couple of wires go to the back of the gauge. What I'm asking is the "ideal" spark plug temp on a warmed up carb'd small block Chevy. I ***ume i'm looking for all 8 to be as close as possible to each other, (fuel distribution), and the hotter, the leaner the mix, or the later the timing, or the hotter the water temp. Keeping the water temp within "norms" and the timing within reason, plug temps should be? I figure I'll hafta take a couple days of driving and rearranging the gauge hookup to get a starting place. Then jet the carbs and check again. Yes this sounds a bit tedious. But then you never know what you've got or if you can make it better 'til you check it out......
I've used these aplenty on air cooled engines, typically called a cylinder head temp (CHT) gauge. As yours gauge suggests, 300 is great, 400 is hot. I've run 425, and seized pistons at 450. No idea how much value it will have on a liquid cooled engine in terms of tuning, will be interesting to see if anyone knows. Exhaust gas temp gauges (EGT) are often the preferred tuning aid.
going to be a little hard to use as the plug is right next to the water jacket and thats will very the temp as the threaded portion will strip alot of heat away from the end and you want to actually read the inner core . one of the troublemakers on here told me how to read spark plugs the proper way by looking at the strap for color and location . and it is the best way to tune a car .EGTs are a way also to do it and so are piezo pressure transducers ..
As said, its best used on an air cooled engine. Reading your plugs is your best tuning aid. The strap will tell you what the engine likes for timing. Cutting the threaded portion off will give you a look at the porcelain, and tell you if you need more or less fuel. Your best bet would be to post the engine specs, and ask what others have had luck with for jetting and timing.
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