I have a question about interchangeable mercury marine motors?

Question

i have a mercury marine 165 hp straight 6 cyl. with an alpha drive,if i want to go to a merc V-8 like a 350 cid or a 305 cid,do i need to change anything behind the engine ,like the transom mount??,lower unit ,engine mount etc.or will the merc V-8 bolt up in place of the 6 cyl engine?

Answer 1

Your question is worded wrong.  The engines, an inline 6 to a V-8, are not interchangable.  You want to know if you can change from a inline 6, to a V-8 and it isn't a good idea.  Boats are built for a specific engine and boats are not like cars, where you can, with slight modifications, swtich engine sizes.

It would make more sense and be cheaper, to switch boats, not engines in a boat.

Answer 2

Everybody thus far has good points!

Changing an engine from IL-6 to V8 is a big deal and you need to thoroughly research what you're doing before you do it!

GMC is right about the gear ratio and the motor mounts. In addition the older IL-6 engines used a special (shorter) splinted shaft on the outdrive upper which would need to be changed. The exhaust pipe (from the manifold to the transom) would need to be changed for a Y pipe style used in V-engines. The flywheel shield may or may not fit (depends on which generation V-8 you used) and if the boat isn't rated for this weight of engine you may end up with an engine too deep below water line which can cause water intrusion and running problems.

Way too much work for very little gains in my book.

Answer 3

http://www.mercurymarine.com/utility/con...

Contact Mercury and ask them!! They are the only ones I would actually trust to give the correct answer about what you're asking, seriously!! You really can't trust some people on the net!!! Talk to the people who deal with these types of questions everyday!! Plus if anything goes wrong you can always go back and sue that company for giving a costumer false information about a product!!! L.o.L.!! Am I right or am I right!!!? Think about it!!?

P.S. When are you ever going to get back onto Yahoo Messenger!!!!!!!!!!!

Answer 4

different upper gear ratio

Answer 5

that #1 drive(alpha was later) has a different upper gear ratio than used on v8 engines. It will prevent you from properly propping the engine/drive and you will have problems with performance and engine rpm's. depending on what year v8 engine(if its a complete engine with mounts and coupler) it may fir your transom bracket. usually when people want to up-power their boat a complete package (new or used ) is the best way and cheapest to go. the engine mounts are also very different from inline to v8