I just recently purchased a 1975 Stingray(My First vette). The engine is not orginal. The previous owner could not offer much info. I was told it was a 350CID 4bolt main modified to 375HP and the auto trans was replaced with a Hurst 4Speed. Cars and parts American ID Numbers Catalog indicates that there are letters on the cyl headPassenger side. I could not locate them. Where all 350 in vettes 4bolt main? Are there any other letters,codes, or dates, markings on the block. Any info would be appreceiated. Thanks Rich :confused:

 

Rich, basically only your higher hp motors in Corvettes were four bolt main motors. L-82s, LT-1s, L-72s, L-88s, etc. All 327s were 2 bolt main motors. Also I believe your 390hp 427s and lower hp 454s were also 2 bolt main motors.

On your '75, the is a "pad"(machined surface) that protrudes from underneath the passenger side cylinder head that is an extension of the block itself. Here is where the "numbers" will be. Remember too, if the engine was ever decked by a machine shop regrinding this surface, this pad area included, your pad MAYBE completely blank, removing any and all stamped numbers. Anyways, a '75 pad might say "V0214CHB" which would be V=Flint Engine Plant, 0214=Febuary 14, CHB=350ci, 165hp, automatic transmission. This is just an example. The second set of smaller numbers might say 1S5435026, being 1=Chevrolet, S=St Louis Assembly Plant, 5=1975, 4=check digit, 35026=the last five digits of the actual VIN of the given Corvette you're checking-again these numbers are just an example, but these examples are typical of what you'll find if "original" type numbers are there-let us know what kind of numbers you see and we'll help you out. Also, looking down at the block flange where the engine mates to the transmission(looking down at the flange kinda like you're looking at the master cylinder or booster)will be a large raised embossed number. 350ci blocks of this era were typically #3970010(mostly 1970-1980 350ci).