More 840 head questions...

[Chevy454]

I recently bought a set of mint 840 heads, and they are currently at the machine shop. Well, I told them to do a basic rebuild on them, and to put the correct for 1969 2.19/1.72 valves in it. Well, they called this morning, and said that they thought the heads originally came with 2.19/1.88 valves, as the area around the seats were uncut and had not been changed. The heads are dated F 7 9 and E 9 9. So, are these late heads, which GM felt were going to be used as service replacements, thus they recieved the 1970 size 1.88 exhaust valve, or... ?

Now, NHRA lists both the 840 and the 291 head as acceptible for use on the '69 L-72, and Colvin's book is unclear about the use of 291 heads (or at least un-clear to me!) in '69. The 291 heads came with the 1.88 exhaust valves, and Colvin said the 840s ceased production around May of '69. So what do we have? Could these be a "combination" 840/291 head? Was the 291 ONLY a service replacement in '69? Were 840s used as service replacements?

I am building this engine for the certified stock class at the Pure Stock drags, so whatever I find needs to backed up with some info.

[Edited by Chevy454 (06-18-2001 at 11:39 AM).]