head temp gauge question

[BP125V]

has anyone tried a head temp gauge from a company besides Digatron? I'm looking for a lower cost alternative.

thanks,
Bill III

[bill van steenwyk]

other sources for head temp guage

You might try some go-cart web sites/suppliers, or possibly jet ski? Dont know whether they use or not. Simplest way is buy a automotive sending unit, drill and tap the head if allowed, and use an automotive guage. JC Whitney probably has something or possibly Autozone, Western Auto, etc.

Good Luck

[17W]

Pyrometer Adapter...

Bill,

You can get a pyrometer adapter for your digital multi-meter.....

[hydroplay]

Try Extech. They make a great number of multimeters. I got one with K-temp and 1 inch digits and a tiltable viewing area for around $30. The K temp stuff is neat in that it is just two very small wires that you can cut to length and twist together and put under the spark plug. And its a great meter for the shop when its not in a boat. Not much need nowdays since the safety nazis imposed a 1/2 inch height for the Yamatos and running that high is childs play.

[raceboat61-S]

I'm thinking of trying an "aviation" exhaust gas temperature probe and guage. I think I can drill a tiny hole and mount this in the neck of megaphone just downstream from the ports of the exhaust stack without too much disruption of exhaust flow. The advantage may be that it will provide more responsive sensing of performance. I'm looking for "just rich of peak EGT" for most power. I don't think a head temp sensor will react quickly enough to minute changes in fuel/air mixture. Discussion? Mike Marshall, Raceboat61-S

[Richard Duncan]

Hi Mike,
I install, calibrate and repair EGT reading and monitoring systems for aircraft. Your real challenge is to calibrate a system. How are you going to determine rich of peak or lean of peak unless you have a target temperature or way of sensing peak? One crude way of detecting peak for a 4 cycle aircraft engine is leaning until there is rapid drop off in rpm and roughness. How can you progressively lean your engine to attain peak?
Regards,
Dick 39P

[raceboat61-S]

Richard, et al,
My experience tells me that calibration isn't important. Relative temperature, is ! I just continue to lean the carb (via jets or needle) until I get to the point that further leaning causes the temperature to start falling, ....reverse (richen) the high speed needle until it passes peak egt, and then just a bit more on the rich side and I have the perfect mixture for that day, that barometric pressure and that outside air temperature. Whaddya think? Mike

[Richard Duncan]

Mike,
You are on the right path! Calibration will help you lean to the optimum temperature when the humidity and altitude change. All the calibration does is determine the target temperature and is marked on the gauge.
Dick 39P

[17W]

Question for you Bill......

Isn't it cheaper to make the investment w/a Digatron tach/head temp gauge, then it is to put your burnt down Hot-Rod back together?

Brent