[pmrath]

I have a good 175 (late '80s) power head that I want to install on a '87 150 (which is blown). The blocks look the same but the intermediate exhaust housings are different - the 175 has a bubble in it just below the block and the 150 does not. I'm assuming that this is a larger exhaust port for the 175. Does anyone know if I can set the 175 powerhead on the 150 intermedaite housing (without the bubble)? It looks like it would save me a lot of time and knuckle busting. Any input on this matter would be GREATLY appreciated.

[Faztbullet]

If the 175 is a 1987 -1991 and has the "bubble back" it is a 3.625 bore( 3 5/8) where the 150 is a 3.500 bore (3 1/2). If the motor is complete just swap them out as 4 bolts hold it to boat/jackplate and install a new impeller for safetys sake.

[jogle1023]

But you need to swap the exhaust tuner from the 175 onto the 150 mid. Everything else will work just fine. As long as you go crossflow to crossflow or loop charged to loop charged...

[pmrath]

Thanks for the info. The 175 is a good runner but the steering arm is shot, rusted right through, that's why I'm making the switch. Do you know if it's a major project to remove and replace the steering arm on these motors after the powerhead is off? If so, that might be the better way to attack this, rather than moving the 175 powerhead to the blown 150s exhaust housing.
Appreciate the help!