[jeffschevelle]

Another interesting tidbit shown in John's early picture is the bypass hose clamp. It is a tower clamp rather than the usual flat style clamp. Assuming those clamps were not changed before the picture was taken (which John's post indicates would not be the case), this tells us his engine was built at Tonawanda somewhere between 5/1/67 and approximately 6/14/67 !

Per a Chevrolet service bulletin dated 5/22/67, 396 and 427 engines built on or after 5/1/67 through “approximately” 6/14/67 used a “new clamp” to prevent the bypass hose from blowing off. Up to that time, the nipples in the intake and water pump had no lips on the ends of them, which (per the bulletin) was occasionally resulting in hoses coming off. Then on “approximately” 6/14/67 a new nipple with a lip on the end went into use at Tonawanda, which allowed them to go back to the original flat style clamp.

The bulletin does not identify the type or the part number of the temporary clamp used at Tonawanda, but it does say that in service repairs if a hose comes off the dealer should use an AC hose worm clamp, part number 3840818 (which is the stainless AC worm clamp with a locator tab sticking out one side). So I had always assumed that Tonawanda also used an AC hose worm clamp on the engines assembly line between 5/1 and 6/14.

But John's picture suggests that they used a tower clamp instead during that period. So now the four NOS AC hose clamps that I had squirrelled away for my two cars with T0509EG engines will have to be put back with my AC parts stash!