My T.T 91 F.S was giving minor problems with poor mid-range running. A new flyer handed me an I.R pyrometer ,we found the mid range cylinder head temp to be 170 F and the max speed temp was 150 F. A small adjust of the low speed needle evened the temps at 150 F and my problems went away. I wonder if anyone out there has used this method for setting an engine. What might the temp range be ? I look forward to the "if's 'n but's "

225-250 F is where most people that use IR heat guns to tune their engines set their engines.

Seems 150F is fairly low. What is your max lean rpm and how many rpm rich is your 150F setting? Just curious.

You need to measure right around the base of the plug on the head. Always try to measure the same place on the head. Above 275 is beginning to get too hot.

This system of using the pyrometer is best used with your own comparisons and would not be good measures for someone else to go by.

Enjoy
Jim

Personally I'd never tune by temperature because there are too many variables that can affect the reading, especially between different engines. A square headed engine like an OS or ST for instance has a greater cooling area than a round head. As w8ye said, the only part on any engine that's much the same is the base of the glow plug so this is where I use my thermocouple but I only do it for interest's sake.

.......I must be using the wrong type of thermometer, cause my engines run best between " porkchop-med and meatloaf-well" :stupid: (sorry - couldn't help myself) hehehe

Ed
You made my day

Have any of you that have a way of checking temperature, compared the temperature difference to the amount of nitro in the fuel?
Use the same engine and take temperatures with 5%,10%.15% and 20% nitro and see what the difference is.

Greg

Would this technique of using temperature readings be a good way of tuning a twin-cylinder/twin carb engine like the saito 300?

To-day I took another look at the head temps.The READINGS from the aluminum and around the plug are in the order of150 F. The black Allen head cap screws showed 225F !!
Many years ago( when worked) I had some experience with I.R pyrometers and found them difficult to use. Thanks to all for the replies -they seem to support my thoughts. The reply from Ed was just so funny and so right .LOVE THAT MEAT LOAF .

OldRookie...the best I've seen for a well tuned engine with different nitro percentages (and the correct plug) is at
http://www.modeltechnics.com/glowplug/firepower.html

Their method for reading temps was to drill a hole within .020" of the combustion chamber for a thermocouple. Some of the results are surprising.

Hello; I took my IR heat sensing gun to the field for two weeks and took readings of all the engines that flew for thoise two days, mostly 4 strokes. There were 3 os 70 surp;s there both days, one was 178 degrees, one was 155, the other was 225, The first one definately sounded better, but all thre of them ran fine with no dead stix. Each of them was on a GB Protoge, the hottest one had a little more vertical, and the coldest one made more smoke. The three guys tried precision airobatics, so it was easy to see the differences. Other Saitos at teh field that day were all near 180 degrees. A few two strokes I measured went from 255 down to 130 degrees. All were measured at the glo plug boss. I try to tune my 4 strokes for 175-180.