Re: 282 head unknown hole size

Posted by HH56 On 2021/1/31 19:47:32

42 would have a sensing bulb connected to a length of spiral wrapped copper tubing going to the gauge. The sealing surface is between the machined bottom of the threaded hole and a flange on the sensing bulb pressed tightly together by the nut holding the unit to the head. No electrical is involved so not too much worry about grounding issues but it would pay to ensure there is no pitting or rusted areas at the back of the hole where the flange could not tightly seal against.

Some modern universal gauges come with adapter nuts for various threaded holes and on the one I used I found the nut or adapter was too short to press the bulb against the rear of the fairly deep hole. In that instance I used an O ring rated for higher temperatures on the bulb between the flange and hole end to make the seal.