how is this done mercury power head swap

**ferdthe4** · 05-19-2016, 11:04 AM

Just saw this and was curious how in the heck this is done of if the larger 90hp L3 power head is able to bolt up the smaller 60hp L3 mid. Also would be nice to know what outboard jet model he is running.

http://semo.craigslist.org/boa/5583055979.html

**home made tunnel** · 05-19-2016, 12:30 PM

Easily - Unbolt the 60hp powerhead, and bolt on the 90hp powerhead. Not all powerheads have the same bolt-pattern... But very similar to putting a chevy 4 speed automatic transmission to a V6 or V8 - Usually the same bolt patterns, sometimes different shaft lengths.

This gentleman must have done his research, and tried it out.

**ferdthe4** · 05-19-2016, 12:57 PM

Ok good to know didn't realize the two power heads had the same mounting bolt pattern. Wonder if the cranks between the power heads use the same splines or if they are different he must have had a 90hp drive shaft cut down and splines cut. Aren't the 75hp L3 the same block and mounting pattern as the 90hp?

**Lil' Blue Rude** · 05-20-2016, 05:05 PM

I've seen this motor on here when it still had a prop lower. It's a 90hp that's been cut down and put on a 60 trim bracket. I didn't get to see it run myself on the river but I know everyone that did see it run talked like it was a pooch, keep in mind we have a 40hp limit on our river. It might be a different story with a prop lower but if it was something hot with a jet it would have been sold by now.

**ferdthe4** · 05-24-2016, 06:16 AM

Ok I so he cut the 90 midsection? I am just kind of curious cause I have a extra 60hp mercury short mid and AG model outboard if the 75/90hp blocks bolt up to the 60 mid it would be tempting to find a 75-90hp with a junk lower or in need of repair to use for a donor power head to put on the short mid I have.

**checkmate45** · 05-24-2016, 09:08 AM

Yeah the mid appears to be the 90 mid cut down with the 60hp swivel on it. The size difference between the 2 blocks is huge, had an l3 60 and ive got multiple l3 75/90's and the 75 is huge

**ferdthe4** · 05-24-2016, 10:33 AM

I knew the size difference was probably pretty big, given the displacement difference between the two 60's and 75/90's. Just never realized the mounting bolt pattern of the two different blocks was same.

**checkmate45** · 05-24-2016, 02:14 PM

The adaptor plate and mid are different, the width where the powerhead bolts go are probably wider on the 75/90. If you measure how wide the 60 bolt pattern is i can measure my 75 to see but i dont think theyre the same