Modifications/equipment changes required to repower from '95 Force 120 to '76 Mercury 1500

[conrad503]

I have a '95 Maxum 1700xr with a Force 120. I recently acquired a '76 Mercury 1500 with power trim and controls. I'm assuming some substantial changes will be required to mount and operate the Merc. For one thing the Force has an electrical tilt mechanism which is really handy when towing. I'm not sure whether that can be modified to accept the Merc. with it's power tilt mechanism, or if this is necessary. I'm a mechanic and a fairly skilled fabricator, I just have minimal experience with boats and especially outboards.

 

[Chris1956]

I had that 1500 Merc, so I am familiar with it. The Force, not so much.

The Merc will have a power trim pump that mounts in the boat. 4 hydraulic hoses will need to be run to the trim cylinders mounted outboard of the transom bracket. There is a 4 wire trim harness that runs to the dashboard. The PTT unit has it's own battery cables.

Since you have controls, use them as I doubt the electrical wiring is the same. The original power trim control on the Merc 1500 was a 3 button panel. This would be mounted in a figure-8 shaped hole in the dashboard. I would convert that to a toggle switch for trim up and trim down.

The Merc uses an older unique bolt pattern with six 3/8" bolts. Two bolts hold the bottom of the transom bracket, along with the top thumbscrews. Four more bolts are necessary, two in each power trim bracket. I expect the Force will have the standard four 1/2" bolt pattern.

Fuel line fittings probably need to be changed over, steering cable should swap easy.

 

[conrad503]

Thanks for the reply. I'm going to try to use the current transom bracket with a single cylinder hydraulic tilt, rather than have to find and mount another pump to operate the 45 year old cylinders on the Merc. That way I won't have to redrill the transom. But we'll see.

 

[Chris1956]

I would be surprised if the transom brackets will interchange. A simple test is to drop the 4 sheet metal screws that hold on the lowermost cowling. Count the powerhead mounting bolts. See if the force has the same amount.

Since the powerhead is the Chrysler design, I do not expect much to interchange.

You can buy aftermarket PTT units. CMC is one such unit.