TOPIC: Mercruiser 120 or 140?

friends,

for you Mercruiser experts, this is likely a DUMB question but i'm going to ask you anyway, as i don't know.
(i've never owned a Mercruiser-powered boat before.)

i bought a 1970 SternCraft 17ft open utility I/O boat/trailer last Friday which has a 4-cylinder Mercruiser engine that's either a 120 or 140HP engine but i don't know which. - there are NO decals left on the engine as the valve-cover/block has been repainted, at some time or other.

so how do i tell which 4-banger that i have and/or what are the outward differences between the two?
(i need to order a engine service manual & want to buy the correct book.)

THANKS for reading this post.

yours, satx

Post a good picture of the manifold & I will identify it for you.

jimandros,

as soon as i get the rig home, throw out the junk that's accumulated in the boat over the last 2 years & cleaned up a bit, i'll do just that.

THANKS.

yours, satx