Best lower for OMC V8

[phantom16ft]

Can anyone tell me which OMC lower would be best to run on an Evinrude V8 gt300? I am running single engine and around 75mph offshore. I will be modifying the mid to run a Merc offshore saddle and trim but I have heard bad things about the standard v8 lower.

I have a magnum 1 lower which I have read is strongest but costs a few mph, I have a set of internals from a lightning 1, a couple standard v8 boxes and a rare second effort racing lwp lower.

Whats the weak point on standard v8 lowers?
How strong is the second effort box compared to the other boxes and can it be made stronger or accept the internals from any of the newer lowers?
Is the second effort lower just a different case with standard v8 internals?

[powerabout]

AFAIK, 2nd effort is just a case with lwp, stock internals.
Unless you mean the twin pinion lower, but thats a bit rare.

I think I would be installing a Merc Sportmaster

[phantom16ft]

I have a few cle's and 2.5 sportsmasters, is there an adapter available to fit these to a gt300 mid?

Are the omc lowers really that bad?

[baja200merk]

3.0 sporty or maybe a torqumaster would work and give you a better gear ratio too. M2 Evinrude cases are tough but huge might hurt top speed.

[FUJIMO]

...don't use 2.4/2.5 gearcases, CLE's etc. use merc 3.0 gearcases of your choosing. yes, the second effort gearcases were stock stuff on the 3.6 johnrudes they sold to the public.

[STV_Keith]

I put Merc 2.5 CLE's under my Monty V8's years ago. They definitely lived longer than the OMC V8 cases, but still didn't love the power. Also, the smaller water pumps struggled to keep up.

If I were to do it again, I'd run 3.0 Merc cases. At 75mph, probably a Torquemaster.

[mrpenguin]

To piggy back off this discussion, does anyone make an adaptor to allow the 3.0 liter Mercury Lower unit bolt up?

Also what if you have the parts, what needed to be done to the engine to convert an OMC V8 to a Fastrack trim unit and saddle brackets?

[STV_Keith]

I don't believe you can do an adapter as the bolt holes are too close together, but not close enough to work. I *believe* (have not seen one personally), that they are welding up the stock OMC holes in the mid and redrilling/tapping them.

[baja200merk]

Yep there is half the bolts to loosen up and you don’t have to readjust motor height or change anything on the mid, water tube, or adapter.

[MattGreen]

No disagreements on the feedback on the various Merc cases, but just a heads-up, I asked this same question a few years ago in another thread, and Al Stoker responded that OMC M2 cases hold up well under V8 torque and only require minor shift shaft mods and a different upper drive shaft. Baja is right that they are fat but so is a regular V8 case. The M2 has factory low water pickup holes too - you might not need a cone.

Matt

[phantom16ft]

Thanks for all the good advice, I will keep an eye out for an m2 case to compare with the stock and second effort lowers. Is the m2 significantly different to the m1 apart from the lower pickup holes?

[powerabout]

You can fit a 300 e-tec case as well with some grinding of the v8 exhuast tube and fitting the older top drive shaft

[V-bottom]

I ran the Offshore Gearcases for almost 20 years without any issues before I sold the boat. Unfortunately Merc 3L cases were not an option 30 years ago.