In response to the exchange on location of the temp probe for CHT, I'll repost this from Dec. of 2003 for your consideration: ================== Howdy, Netters-
I got my "Beetle Flyer" (from Great Plains Aircraft Supply) over the weekend and took notice of a tech tip on locating your CHT sensor on the VW engine ( down the page, at http://www.greatplainsas.com/bf20032.html ). Standard practice is to install it under a spark plug, but Steve Bennett points out that your CHT temps will read high if you do this... by as much as 150F. He recommends installing it under a head stud (location is given in the text in the Flyer, but not as clear as it could be). Long and short of it is that if you're running a VW and have your CHT sensor under a spark plug, you may not be getting readings that reflect what you're really interested in. If Bob Hoover is still monitoring this list, maybe he would care to chime in? If Steve is monitoring this list, maybe he would care to elaborate more clearly on the preferred location? The picture in the Flyer identifies a boss that is used for fuel injection temp. probe, but doesn't say this is the recommended spot (and doesn't seem to be a good spot anyway). The idea is to respect the metallurgy of the head castings by not allowing the CHT to exceed recommended temperature... bad and irreversible damage can result if the metal gets too hot. Oh, and somewhat timely and related to Mark Jones and Mark Langford's two different approaches to cooling plenum on the Corvair, the Beetle Flyer also addresses cooling plenum design for the VW on the above-referenced webpage. Oscar Zuniga San Antonio, TX mailto: taildr...@hotmail.com website at http://www.flysquirrel.net
