2.5 Sportmaster to Shorty OMC Mid

[aj06bolt12r]

Im looking to adapt my 2.5 sportmaster to work with a shorty OMC mid... Who is willing to point me in the right direction or refer me to the man who can make it happen. I know it's been done by guys on here. I searched the threads but Im not totally clear on what all needs to happen. Thanks!

[Instigator]

On to who’s and what mid??

Ive done a couple on Taylor mids w/the Merc bolt patterns for the case.

Drive shaft, shift shaft and water tube all need shortened.

Drive shaft needs cut to OMC splines.

OMC shift shafts raise/lower to shift the case.
Mercs rotate the shaft so that must be engineered.

Other than that, it’s a piece of cake ��

Im looking to adapt my 2.5 sportmaster to work with a shorty OMC mid... Who is willing to point me in the right direction or refer me to the man who can make it happen. I know it's been done by guys on here. I searched the threads but Im not totally clear on what all needs to happen. Thanks!

[aj06bolt12r]

On to who’s and what mid??

Ive done a couple on Taylor mids w/the Merc bolt patterns for the case.

Drive shaft, shift shaft and water tube all need shortened.

Drive shaft needs cut to OMC splines.

OMC shift shafts raise/lower to shift the case.
Mercs rotate the shaft so that must be engineered.

Other than that, it’s a piece of cake ��

I have not seen the mid in person yet. Going to get it Friday. But I'm told its a shortened factory OMC 3.0 looper mid. I was thinking there was an adapter plate out there that could be used to get it to bolt up. Would still have to deal with the rest of the issues you mentioned. Then if using the adapter plate that would change the needed length of the drive shaft, shift shaft and water tube. Do you know of anyone who can/will cut down the Merc shaft and cut OMC splines?

[aj06bolt12r]

Ill have a nice lightning 1 gearcase that fits the shorty mid but I'm not sure I want to run it on my Allison. I don't know how they do surfaced or what speed they tend to blow out. You think its worth getting that coned or should I just spend that money getting the sporty stuff adapted?

[FUJIMO]

...lot less work($) using the omc l.u...

[BarryStrawn]

How much horsepower and how fast are you wanting to go? Sportmaster may not be the best choice.

[aj06bolt12r]

I'm sure it would be cheaper to use the L1 OMC LU. But I'm not sure how safe it would be. How fast are they considered safe before blowout? Like the general rule for a Merc Torquemaster is something like 82-85 before they will usually blow out... What is that number for a L1 OMC case? What kind of power can they survive behind?

How much horsepower? I don't exactly have a dyno number. It's a Monty Race ported 3.0l looper with custom fuel injection and a Brucato PCU running it. Pump gas tune and heads 145psi on all six. I'd say... quite a bit.
How fast do I want to go? I'd like to run low 100's. Boat is an Allison XB 2003. It ran low 90's with my Promax before I melted #6

[STV_Keith]

I put CLE's on V8 OMC mids, which is the same pattern as a Sportmaster. Just need an adapter plate. Jack Barsh can shorten the mid from 20" to 16", not sure if he can do anything with the bolt pattern. I believe JPEROG on here has welded up the OEM holes in OMC mids and redrilled the bottom to accept the Merc pattern without an adapter plate, so maybe contact him.

[Instigator]

I think that id for a 3.0 Sporty which is a different pattern than the 2.5.

Bajamerc does them all the time.

I believe JPEROG on here has welded up the OEM holes in OMC mids and redrilled the bottom to accept the Merc pattern without an adapter plate, so maybe contact him.

[Instigator]

On the Lightning’s, they have a horrible reputation, especially w/any power put to them.

That being said, I’ve built a few, including one on a 300-ish hp 3.3 looper w/zero issues.
But…….,I only have a couple hrs on it.

The theory is, the housings flex under load, the gears go out of alignment and boom!

If your mid has OMC bolt pattern, I’ve run coned OMC cases over a 100 many,many times.
Heres your question to the nay saying experts, “if I am surfacing my case, who cares what it looks like?”.

If you dig deep enough on here, you should be able to come up w/one I did.

I added/welded a slab on the factory skeg, making it deeper and longer.

Ran low 100’s on an STV and similar on an Xr2002.

Ran it on a Hydrostream Vector at 101.

Happy to help if i interested.
If so, PM me and we’ll swap #s.

I type too slow to think it’s fun.

I'm sure it would be cheaper to use the L1 OMC LU. But I'm not sure how safe it would be. How fast are they considered safe before blowout? Like the general rule for a Merc Torquemaster is something like 82-85 before they will usually blow out... What is that number for a L1 OMC case? What kind of power can they survive behind?

How much horsepower? I don't exactly have a dyno number. It's a Monty Race ported 3.0l looper with custom fuel injection and a Brucato PCU running it. Pump gas tune and heads 145psi on all six. I'd say... quite a bit.
How fast do I want to go? I'd like to run low 100's. Boat is an Allison XB 2003. It ran low 90's with my Promax before I melted #6

[aj06bolt12r]

Thank you Instigator I'll do that.

Matt Green. I'm interested in your adapter but your PM box is full

[aj06bolt12r]

If anyone on here knows Matt Green tell him to hit me up please. 615 339 7043

[BarryStrawn]

aj06bolt12r - I knew someone with a very spicy Dave Bush powerhead on an XB2003 a few years back but don't recall what he ran for mid, lower, gear or props. I'm looking for his contact info but nothing yet. Will let you know...

[aj06bolt12r]

aj06bolt12r - I knew someone with a very spicy Dave Bush powerhead on an XB2003 a few years back but don't recall what he ran for mid, lower, gear or props. I'm looking for his contact info but nothing yet. Will let you know...

Ok awesome! Id definitely be interested in hearing what worked for him.

[MattGreen]

Thank you Instigator I'll do that.

Matt Green. I'm interested in your adapter but your PM box is full

Inbox cleared out, sorry about that.

Matt