Originally Posted by 406 bug
Your right, the problem has come up before. When you purchase an AutoMeter temp gauge, the package contains, adapters/ reducers so it will fit most applications (such as yours). If you feel usure of using a reducer based on what others have indicated, call the Autometer folks and obtain direction from them. I think you will find that its ok.
What I have seen, the 'threaded' hole in a Vortec head is 1/4NPT.
I have "adapters" in stock, and from what I see, by the time you 'drill' them out to fit the stock "temp sender probe" they will 'break if you sneeze'.............
There is no way this will work!
waiting for a 'pic'.