Re: does anyone know if a 78' 90 hp mercury tilt trim fit a 74' 85 merc. tilt trim?
I'd expect your 90hp Inline Six has an externally-mounted pump, with (2) tilt-n-trim cylinders mounted on brackets, in place of the standard shocks; (2) hoses per cylinder.
This setup will swap directly to your 85hp.
When you do this mod, leave out the shift interlock actuating cam. Just pull it off the 85hp lower unit's shift shaft. You won't need the mechanical reverse lockout mechanism since that function is accomplished by the power tilt-n-trim cylinders.
You'll find a travel-limiting strap on your 90hp, hopefully you'll be able to get out the parts that hold this strap in place and transfer the strap over to your 85hp; if not, you can have a new strap sewn up using an equivalent rot-resistant, non-stretching-type strap. This strap is a safety device to prevent overtravel of the motor when in the tilted position; you'd run without it at your own risk.
One alternative would be to swap your 85hp powerhead onto the Six-Cylinder exhaust tower. The exhaust tuner tubes are different between Four and Six, so you'd have to swap over the 85hp tuner plate as well.
If your motor isn't a Salty Dog, it should come apart relatively easily. If not, an application of PB Blaster or equivalent rust-buster should help. As will application of heat from a propane or MAPP torch. Use caution when applying heat after penetrant, as most are flammable.
HTH.............ed
