Convert BlackMaxx to longer shaft length

[tbird175]

I have a 175 HP 1978 mercury BlackMaxx engine. It is classified as long shaft, but that was only 20" back then. I would like to convert it to a 25" shaft to use it on later model boats. i have been told conflicting information about this. Some say that it can not be done and others say that it can be. Can any of you Merc mechanics set me straight on this?
Thanks.

 

[boobie]

Re: Convert BlackMaxx to longer shaft length

Try Bay Mfg.com.

 

[Mi duckdown]

Re: Convert BlackMaxx to longer shaft length

Good luck.

 

[Chris1956]

Re: Convert BlackMaxx to longer shaft length

Longshaft was and still is a 20" shaft. You want an XL shaft to achieve 25". XXL is a 30" shaft.

On that old motor, an XL shaft may not be avail.

You need to ask the forum what XL lower units will fit your application, and what items (water tube, upper shift shaft) you need to install. Sometimes water tube extensions are avail. Not sure about shift shaft extensions.

 

[Dukedog]

Re: Convert BlackMaxx to longer shaft length

Try Bay Mfg.com.

Part number 612

 

[tbird175]

Re: Convert BlackMaxx to longer shaft length

Thanks for the info.