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914World.com _ 914World Garage _ Cylinder Head temp sensor

Posted by: Joe Owensby May 8 2008, 09:43 PM

I have one of the Dakota Digital CHT sensors. Works great by the way. However, I have a question on the sensor that goes beneath the spark plug. Do these normally get distorted? See photo below. Using this on a set of heads from a Raby kit, with the smaller spark plugs. The sensor fit reasonably well on the plug, but it is now distorted from clamping down on the head. Thanks, JoeO

Attached image(s)

Posted by: SGB May 8 2008, 10:02 PM

Seems like it would not seal right. Is the opening sized for the smaller plug?

Posted by: Joe Mama May 8 2008, 10:29 PM

I put mine under the plug and then slip the washer back on....

Posted by: type47 May 9 2008, 08:34 AM

mine got distorted/bent up when i installed it under the plug. i seem to recall there are 2 ring sizes available for the thermocouple so maybe the smaller ring would fit your smaller plugs better.

Posted by: HAM Inc May 9 2008, 08:42 AM

Yes, you'll need the 12mm thermocouple. That is the same set-up we use on our race car, with no issues.

BTW, how does it run?

Posted by: toon1 May 9 2008, 08:57 AM

Same thing happened to me. I made one out of a piece of copper , worked good

Posted by: purple May 9 2008, 11:24 AM

i would take the sealing washer off the plug if you put a ring thermocouple underneath the plug. that's what I did...

Posted by: Joe Owensby May 9 2008, 11:21 PM

Thanks everyone for the suggestions. I will get a smaller thermocouple.

Len, the engine runs good, lots of pep, etc., but it still wants to run hot. CHT temps will go over 390 if I drive up a long slight incline on the interstate at 70 or so in 5th. Dropping down to 4th brings them down to 375 or so. This is at only about 75 outside temperature, so it should be lower than that. CHT temps are about 360 when driving hard in lower gears.

The engine has some old DRLA 40 carbs that came with a parts car, and were rebuilt by Art in Utah, per Jake's recommendation. They have 60, 140, and 180 jets. I am not sure about the venturis. I had an old std distributor, and also tried an old 009 distributor. I just received a new Mallory Unilite and coil today that I briefly tried, with not much improvement, although the engine ran a little smoother. Timing set at 27degrees at 3500RPM. All cooling tin is installed, and flapper is free. Checked the jets, and they seem clean. The only thing that seems out of what I think should be there is the idle mixture screw on cyl 2 has to be turned almost all the way in to cause a noticible drop in rpm. The others cause an effect a little sooner (starting with about 3 turns out as suggested by the Dellorato manual). I set the idle screws out 2 turns from where the engine started to stumble as they were turned in. Only have about 180 miles on car, all in short trips to check out operation and cooling. Any suggestions, or recommendations of a good mechanic in north east SC? thanks, Joe