Identify Mercruiser Chev engine

[djrmj]

I have acquired a chev mercruiser SB engine. Need to know which model and how much HPower it has.

I found a service manual for 1978-84 models and it shows a distinctive shape stamped into each end of the heads to signify hp. It also shows a Mercury number stamped into the block.

I cant find the number stamped into the block, and the shape stamped into each end of the heads is a block letter " L " laying anticlockwise on its back. This is not same as my book so must be different year.

Looking for help with identifying motor please.

[Galaxie_406]

Without knowing if the engine is OEM and never been rebuilt it's a little tough.
If you can get me the actual block casting number as well as the head casting numbers I can at least decipher a little for you.

Being that you have ab early book, could you check my latest post "OMC /SBC Question" maybe your book will have the information I need.

Thanks Gary

[RMSOSF]

should be no Mercury # stamped into the blok, but there should be a tag on the side of the block where the flywheel housing meets the block