Cracked mercruiser 260

[powerstrokeplumber87]

I have a mercruiser 260 that has a crack under the exhaust manifold in the block. Can I change it out with any 350 block from any year truck or car. Boat is an 86 I have my hands on a 1990 350 engine block. Tia

 

[Kola16]

That depends. What is the block's serial number? 1986 is when Chevy went from a 2-piece rear main seal to a 1-piece. So it depends if your boat manufacturer put a 1985 block in it or 1986 block. The serial number will tell you.

 

[Scott Danforth]

I have a mercruiser 260 that has a crack under the exhaust manifold in the block. Can I change it out with any 350 block from any year truck or car. Boat is an 86 I have my hands on a 1990 350 engine block. Tia

if your 1986 boat has a 1986 motor (center mount valve covers, 12 manifold mounting holes and 1-piece RMS), then it is the same as your 1990 motor

if your 1986 boat has a 1985 motor (2-piece RMS), then you will need a flywheel to go along with your 1990 motor

the block crack is from poor winterization. I would also suspect the exhaust manifolds are cracked. so you will need new manifolds. the heads may be bad as well.

your truck motor will need to be stripped down. you will need to install brass core plugs, marine head gaskets and install a marine circulating pump (you should be able to use your old one)

then transfer all the stuff from the marine long block onto your long block

this is the time to upgrade to vortec heads should you choose to.

 

[tank1949]

I have a mercruiser 260 that has a crack under the exhaust manifold in the block. Can I change it out with any 350 block from any year truck or car. Boat is an 86 I have my hands on a 1990 350 engine block. Tia

If the

I have a mercruiser 260 that has a crack under the exhaust manifold in the block. Can I change it out with any 350 block from any year truck or car. Boat is an 86 I have my hands on a 1990 350 engine block. Tia

I have a mercruiser 260 that has a crack under the exhaust manifold in the block. Can I change it out with any 350 block from any year truck or car. Boat is an 86 I have my hands on a 1990 350 engine block. Tia

change to motor out. Be prepared for possible different flywheel bolts. Remember that you will have to marine it.