Reply to "Factory fitted Holley"

> Australia never cast ONE large port (4V) head, ever

Actually, they did but not for production engines. When the inventories of
4V heads ran out in the mid-seventies, Ford Australia cast another batch in
1976. The 1976 re-casts were modified "D1AE-GA" castings and will bear that
number under the intake ports. They incorporated revisions to minimise
warpage, especially at the ends of the heads where the large square holes
meet the block surface. These heads were machined asstandard 351-C 4V heads
(Part # D1AZ-6049-B) and also as Boss 351 heads (Part #D1ZZ-6049-B). Both
used the same common casting, differing only in rocker pedestal and spring
seat machining differences. The casting dates were typically June, 1976.
There was also a further production batch made in March of 1978, these
supposedly had a little more meat added to backs of the chambers (directly
under the rocker pedestal) to minimize flexing under the the rigors of NASCAR
abuse.

Dan Jones