i'm having issue with springs touching the stock 273 , but when i measure the spings install dia is 1.49 od . engine builder install them . went in to readjust the valves do to noisy operation of the valve train . this cam is little , idle to 5k . just a driver . wounding why such a big dia springs .
pomonamissel - im not sure how old your heads are or what has been done but if your engine is a 273- im sure it does not have hardened valve seats unless you had them done.
From the factory the 318 and 360's - SOME newer models had it done but not a full hardened valve seat, just induction hardening. This is where they harden just the edges of the valve seat and not any more. in a production head- that would cost a lot of $$$'s for the manufacture to do. Anyhow if the valve over time has sunk deeper from wear at the seat, the valve stem moves upwards (closer the the valve cover) as well. Now your rocker arm is sitting at the wrong angle and the geometry is off. The wear on the rocker tip is greater as less surface area is touching the valve and the more noise is made.
Large diameter springs are used for longevity- if you are using factory springs. Sorry if this is actually not fitting your topic- your post was kinda vague- more information is help full.
Besides this is a post about my information on my car..LOL!:lol:
Joe