The International Cessna^® 170 Association

Which one do I need, bayonet or washer type cht probe? Also how far down the exhaust manifold can I place the egt probe? Mechanic says that it will hit the clamps if 4" is followed on the O-300A. Can it be installed at 2"? Will the probe be too hot possibly damaging it?

Alvin,

Unless you have ECI cylinders with the boss for bayonet probes, you'll need the spark plug gasket type. Just an interesting note, but ECI has a service bulletin on the bayonet probes that lowers the maximum cylinder head temperature from 525F to 500F when using these probes due to the fact they are installed in a cooler location on the cylinder. The highest I've seen so far is 400 in an extended climb on a hot day (gotta love that new baffling!)

I just installed an Electronics International UBG-16 engine analyzer, and they recommend installing the EGT probes 2" down from the cylinder port. This puts them about halfway down the riser. For a picture of the installation look about a quarter way down http://cessna170.org/phpBB2/viewtopic.p ... &start=105 . I have some better pictures if you're interested. For clearance with baffling, cowling, etc., I installed mine about 45 degrees clockwise from straight out (toward the front on the left, toward the rear on the right). Your mileage may vary.

Miles