Jon,
I guess this thread has strayed a bit, but then there haven't been any new votes for the most "significant" in a while, so I guess it's ok (right Charley?
)
Regarding the 50 or 57 number, I know there have been MANY quotes by magazine writers, etc stating 57 was the number. Several people who have been digging into the history of those cars for many years believe the number is really 50. A production report issued by the Tonawanda engine plant (dated I believe July '63) lists production of total engine assemblies at 50. It lists other partial engines that were shipped, but only 50 complete units. I don't believe the Flint plant would have built a car from a partial engine plus the extra parts. They were not in the engine assembly business.
Now as to short-comings, I don't see any with the engines themselves. Raising the ports on the heads and using a 2-piece intake manifold was an engineering leap for that W design in '63. Along with pushrod guides and an aluminum water pump (which I forgot to add to the earlier list
), they made more milestones with that engine (surpassing any other Chevy design of the time).
The short-comings I see are subjective. I don't see that they did anything "wrong", but I feel they stopped short. It's as though all the engineers on the project wern't on the same page, all working toward the same goal.
For instance, they took the time to replace 2 grille brackets, that weighed a few ounces, with aluminum ones. They replaced a battery tray that weighs about 2 lbs with an aluminum one. But then they also designed an all-new air cleaner the size of a washing machine and built it in steel! They did not move to an aluminum radiator. I think more items could have been made of aluminum, but then, they might have learned an expensive lesson when they ruined a set of inner fender dies making the aluminum ones for '62.
The weakest point of a '63 passenger car was the rear axle assembly. Most other serious drag racers had already added a left upper rear control arm to control housing twist, but (again, contrary to rumor) they were not provided on the Z-11 Impalas.
A heater delete option was not part of the RPO Z-11 package. Someone just simply forgot......or thought they were also building a race car that could be driven to the store in the winter.
It was up to the buyer to realize a heater was standard equipment on a '63 Impala, thus he should specify the delete option. There are several known Z-11s that were delivered with heaters.
And of course, they did not go to the extent that Ford or Mopar did with light doors, teeny seats or a trunk mounted battery.
All those subjective short-comings aside, I still believe the RPO Z-11 was Chevy's most serious attempt at building a complete race car bundled in one RPO, available to the public (although few), with such an assortment of unique equipment not available on other models.
Verne :beers