1978 Mercury 90HP serial number 5033791

[Gomer50]

I picked up a 1978 90hp inline 6 for next to nothing (0=$) and it looks good.There are however a few questions I would like to throw out here.With todays gas what should this one be set at for WOT degree wise.Also the switchbox looks to be damaged,is there a difference between 332-2986 inline 4 and 332-2986 inline 6 switchbox? And one other question this model calls for coil 332-4895T2 and I have one 4895A1 Ignition Coil 85 hp are these more or less the same (they look the same)?
Did a compression check all the way down 140 except number 3 which was reading
110. So I took the cover off on the starboard side for cylinder 3 and 4 and found a bunch of aluminum shavings,frozen rings,scored piston.I decided to take the whole motor apart to check things further.Number 3 piston wall was scored as well. So I honed it out (looks good),popped in a another piston and should be good to go.I do have one other concern the trigger (distributor) wires are shot so I would like to take one of my good 4 cylinder distributors apart and switch out the window disk.Is there anything special about these disks? I read on Cdi website that one side of the disk goes up,is there some special coating becuase the one I have is scratched up. This might be the dumbest question but never hurts to ask..

 

[daveswaves]

Re: 1978 Mercury 90HP serial number 5033791

I picked up a 1978 90hp inline 6 for next to nothing (0=$) and it looks good.There are however a few questions I would like to throw out here.With todays gas what should this one be set at for WOT degree wise.Also the switchbox looks to be damaged,is there a difference between 332-2986 inline 4 and 332-2986 inline 6 switchbox? And one other question this model calls for coil 332-4895T2 and I have one 4895A1 Ignition Coil 85 hp are these more or less the same (they look the same)?
Did a compression check all the way down 140 except number 3 which was reading
110. So I took the cover off on the starboard side for cylinder 3 and 4 and found a bunch of aluminum shavings,frozen rings,scored piston.I decided to take the whole motor apart to check things further.Number 3 piston wall was scored as well. So I honed it out (looks good),popped in a another piston and should be good to go.I do have one other concern the trigger (distributor) wires are shot so I would like to take one of my good 4 cylinder distributors apart and switch out the window disk.Is there anything special about these disks? I read on Cdi website that one side of the disk goes up,is there some special coating becuase the one I have is scratched up. This might be the dumbest question but never hurts to ask..

With todays gas I set them at 19 degrees before TDC, there is no noticable reduction in power at all, just safety for piston no 3 as you found out. There is no special coating on the distributor disk, the reason there is a top and bottom is one of the windows in the disk is narrower than the others. I usually just mark with a felt pen before I take the distributor apart. I would suggest that you check the bearings in the new dist before you re assemble, good time to change them.
The switch boxes are identical.