"Ben Jackson" wrote in message
news:Xm1cc.181337$1p.2150841@attbi_s54...
I understand that if I had a CHT, and it had a redline (I don't have one
at all, probably because the PA-24 doesn't have cowl flaps) I would need
to keep my CHT or get something certified to be a primary CHT.

Are there any rules regarding EGT? The one I have is pretty useless.
It's
an analog gauge that displays only relative EGT (it's marked in 100s of
degrees F, and a thumbwheel lets you adjust the position of the indicating
needle). I'd just leave it, except it's a 2.25" instrument right where
I'd like to put the digital replacement.

Lycoming IO-540, right?

Definitely the EDM-700. http://jpinstruments.com/edm_700.html along with a
set of GAMIjectors.

You can probably get one cheaper, but not likely _better_.