I am in the process of re-powering my '79 255 Formula Liberator w/Alpha Drives.

The existing 260 Mercruisers are pre Vortec with 2: piece rear main seals.

I can get a great deal on New Mercruiser Gen+ crate motors that are Vortec bases with roller cams, complete with ignition and fuel system. I know I am looking at a different flywheel requirement as well as exhaust manifolds (maybe). My question is as follows:
Are there any issues with external brackets, bell housing configuration, reverse lockout issues or any other issues that I am overlooking?

I am at a crossroads on which way to go with this. If I can easily drop in a pair of these crate motors it sure would beat building two new motors from GM Marine base engines....but if I have to I will.

Update:

Spoke to the very helpful folks at Michigan Motors and learned the following:

1. Need 12-3/4" Flywheel to work with the early bell housing and starter.

2. Need Updated coupler to match with the new style 1: piece main bearing crankshaft.

3. All brackets, hoses, thermostat housings, and exhaust manifolds will work with the Vortec engines.

4. The shift brackets cross over with out issue.

Stay tuned...

5. I am adding a remote oil filter kit to each engine because on mine you can't even see the oil filter much less get to it.

You'll have to switch to electric fuel pumps.

Jeff

i think you need different flywheel housings also .the bigger dia flywheels dont fit in them

1. Need 12-3/4" Flywheel to work with the early bell housing and starter.

Need smaller flywheel as opposed to my 14"...roger that.

Negative...comes with all fuel system components...including mechanical fuel pump installed.

http://www.michiganmotorz.com/mercru...ne-p-1209.html

I think this is going to be a winner...

That looks like a great package!

Jeff

I think it's going to be bolt in...I suggest redoing oil lines, cooler, filter mount etc...

I agree...Michigan Motorz sells the remote oil kit from MerCruiser and I am getting two. As I have said...I can't even see my oil filters in their current configuration.

For simplicity I plan to keep the log style exhaust manifolds which will probably require that I fabricate a custom bracket to mount the remote oil filters. I am thinking that I can use something similar to the water separator mount that attaches to the front of the starboard side exhaust manifold. I am doing quite a bit of pre planning and think the only thing I haven't covered is the dip stick. I will consult with MM before shipment to make sure I have that covered.

I can go up in power for about $500 per side but in the long run I don't think it's worth the extra bucks. Torque is what we all go for in a boat anyway...and all the higher horse power versions do is move the torque peak to a higher RPM.

My goal is long-term reliability with the ability to run long distances at a sustained 45~55 mph without killing the engines. That will let me run to Freeport/Lucaya in a little over an hour on less than half a tank....pretty decent safety margin.

Roger and crew at Michigan Motorz do a good job with their replacement marine engine packages and that seems like an ideal upgrade engine for your boat.
Being your old log manifolds might be near end of life and you certainly don't want to destory two of these new beauties with an exhaust water leak you might want to consider the change to a nice header or header manifold with a dry joint riser that would probably get these engines up closer to 300HP and some better volumetric efficiency which can translate to better fuel mileage.
Good Luck with your upgrade.

Best Regards,
Ray @ Raylar