I saw a post on this site about someone who installed 1.94 valves on a 305 head. What wasn't specified was whether or not there was machine work required or if the valves just drop right in? Any clues?

 

Of course there's machine work... kinda hard to jam a 1.94" piece of metal into a 1.84" hole, eh?

Beyond just cutting the seat bigger, in order to get any benefit out of doing this, several parts of the head need to be opened up. Specifically, the throat of the bowl, right behind the valve (which is already not fully the size that the 1.84" valve can use), and the "wall" of the chamber next to the intake.



Not hard to see in this pic, which is a 081 head from a 87-92 non-TBI 305, how bad the chamber wall interferes with the valve. After all, it's kinda hard to get more stuff to come through there, if it all has to go through a little crack that's just got smaller because you put a valve that's bigger in the way.

No clues, though. Sorry.

 

Haha thanks for that explanation. That really clears things up!