Which Mercruiser engines...?

[lord frith]

Hi all,
First post, if that matters. Anyway, I have a 1989 Mercruiser 4.3 and outdrive. Which Mercruiser engines can I use to replace the 4.3? I am not concerned with adding a larger engine and accompanying increase in horse power. I have my eye on a couple of 5.something engines. Advice please.
Stephen

 

[Scott06]

Hi all,
First post, if that matters. Anyway, I have a 1989 Mercruiser 4.3 and outdrive. Which Mercruiser engines can I use to replace the 4.3? I am not concerned with adding a larger engine and accompanying increase in horse power. I have my eye on a couple of 5.something engines. Advice please.
Stephen

If you have room in front a 5.0 or 5.7 will work fine. If you are not looking for more hp why are you asking about replacing the 4.3 witha 5 something ??

the 4.3 and the sbc have a common lineage front and back are same on blocks , sbc is 4.5” longer otherwise easy swap

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Generally speakin', when ya change the number of cylinders the motor has, ya gotta also change the outdrive gear ratio,.....

 

[Scott Danforth]

Hi all,
First post, if that matters. Anyway, I have a 1989 Mercruiser 4.3 and outdrive. Which Mercruiser engines can I use to replace the 4.3? I am not concerned with adding a larger engine and accompanying increase in horse power. I have my eye on a couple of 5.something engines. Advice please.
Stephen

What is wrong with the 4.3 and why do you want to change. Easiest would be a vortec headed 4.3

 

[QBhoy]

As bondo has said…if you go too much larger, you’d half the time need to think about drive ratios. If you’re lucky you might have one of the higher ratio 4.3’s like a 1.6. Then you might get away with a prop pitch change perhaps. But usually the more powerful of the v8 short blocks might use a 1.47 ratio. I know my 18ft with a v8 mpi merc uses a 1.47 alpha

 

[achris]

Hi all,
First post, if that matters. Anyway, I have a 1989 Mercruiser 4.3 and outdrive. Which Mercruiser engines can I use to replace the 4.3? I am not concerned with adding a larger engine and accompanying increase in horse power. I have my eye on a couple of 5.something engines. Advice please.
Stephen

What boat is it in? What is your current propeller pitch and drive ratio? Is there a problem with the 4.3?

Chris.........