What's the difference between 72 ga heads vs. 68-69 c heads? How can I tell if the ga heads are from a W-30? I've read on COTech section that is was a w30 but didn't have large valves. Someone please clarify........

 

Large valve Ga heads were used on 1972 W-30s (X code) and 1972 455/M20 4 speed (V Code cars). That's only approximately ~1,600 cars total. Not sure about Toronados. All other 1972 455 applications used small valve Ga heads. I need to dig up my specific info but the valve angles were different on the large valve heads too. As far as external identification, there is a debate that the three "ribs" on the casting of certain Ga heads possibly indicates that they are large valve heads, but I don't think that was ever proven conclusively.

Others will chime in on this I'm sure.
Terry

 

This is where I saw the w30 info...http://tech.classicoldsmobile.com/43.shtml. Casting#409100. Stating w30s. Hardly any were big valves if any at all.

 

If vie got small valve ga heads and plan to get a valve job to mark them large valves, wkd it matter if I were to get c heads with large valves even if they have to have machine work done?

 

I have several sets of GA heads, and iirc the small valve heads had 45 deg seat 2" intakes and 30 deg seat 1.68" exhaust valves. The large valve heads had 30 deg seat 2.07" intakes and 45 deg seat 1.63" exhausts. The latter heads should also have pressed in hard exhaust seats. All the GA heads ( and E and G heads) have "ramps" in the intake port floors while the A,B,C heads have the floor dropping right to the seat. The 70 up heads also have lowered intake port roofs to allow for valve rotators which lower the valve spring seats for a taller spring installed height.

 

I've never seen a factory pressed-in hardened seat. I thought all the factory hardened seats were induction hardened.

 

Joe, please see p. 6B-16 of the 1972 fsm for verification that those heads indeed had pressed in exhaust seats.

 

Thanks. The 1972 CSM is one hole in my collection.

 

So what about the '71 G heads, induction hardened or pressed in?

 

Acc. to 1971 fsm, 442 and Tor have seats and bigger intake valves. however, no 1.68" exhaust valves; all 455s have 1.625".