Found a guy who claims to have one out of a 68 GTO.
The casting #16 is only on 1 exhaust port. Not 1 # on each ctr port like i'm used to seeing.
Could this be the small vlv hds?
Did the small vlv hds have pressed in, or screw in studs?

He's goimg to pull a vlv cvr and check.
Also get me the engine serial #, date code, intake #(4-bl), and dist #.
No carb.

Thanks.

Small valve 16 was 1970 only, pressed in studs 1.96/1.66.

They could be 216 casting heads...don't remember enough about them to elaborate.

Very early August-September-October '67 build, most likely.

AFAIK same specs as other '68 #16.

Never heard of 216's. Wonder what they were used on.

So, early production, but the same as later ones?
IE; big vlv, screw in studs.

That's what I've heard. 216 may be another callout for them, if the casting # under the rocker cover ends in 216. Wallace Racing lumps 16 and 216 together for '68. 216 are listed GP and Firebird, 400 and 428.