It is my understanding that a 327/250HP engine was cast and assembled in other than the Flint assembly plant and that the 327/300HP was produced at the Flint plant (only??). I have a mid-1963 block (327/250HP) STAMPED with a "T" on the ID pad…the short block cast number also has a "3T" CAST in it next to the casting number…..Do 327/300HP short blocks have an "F" cast into them?? thx…Billu38

if the machine assembly stamping on a 870 casting numbered block begins with a T, then the block was cast in tonownda. if it begins with an F, that block was machined in flint michigan. both flint and tonowanda assembled 250 and 300 hp blocks. all 1963 Corvette engines came from michigan. No 1963 corvette blocks originated in New york. mike

OK…that speaks to machining but would a block with an ID of "F" stamped have a casting marking with an "F"….that's my question…thx…Billu38

i've never seen an F casting mark on a michigan cast 870 but i have seen a tonowanda casting figure( recall it being a T) on the drivers side flange just outboard of the 870 casting on a new york casted block. that particular tonowanda cast block was a 63 pass car 250 hp engine. hope that helps, mike

The Flint cast blocks are easy to identify at a glance because the "870" casting number is much larger than a Tonowanda casting number.

by about march of 1965, the height of some flint 870 casting number shrunk to the small size of then current tonowanda 870 castings. i have a 63 870 from tonowanda that is the large size casting # like flint casting #'s. mike

Mike…my understanding, as I stated in my original question, was that all 300hp engines came from Flint…and the 250hp from Tonowanda….this is not what I hear from you??? thx…Billu38

The July 63 Tonowanda 250 casting I have has 3/8 inch. high 870 cast numbers…Billu38

Bill,
My records indicate that between '62 & '64 the passenger car 250hp engines were supplied by both Tonawanda and Flint, but the 300hp only came from Flint.

Verne

Verne, any particular reason why? When cylinder bore dias. etc were the same and real differences were add on parts? (crankshaft, carb etc.)…Billu38

I can only imagine it was due to cost savings. If one plant could supply the demand for the 300hp 327s, then Tonawanda saved the cost of casting the heads, intakes and exhaust manifolds.

Verne