78 mercury 1400 with a 1961 800 fgs lower unit

[angelvigil03]

I'm wondering if some can help. I bought a pontoon boat with a 78 mercury 1400. I was trying to perform some maintenance on the outboard and could not find the water pick ups for the impeller anywhere. Turns out some one put a 1961 merc 800 fgs lower unit on the motor. The water pick up is the Trim tab and has holes in it. I took the boat out on the lake and everything worked great. Except I noticed the water stream wasn't as good as I think it should be. So I am trying to figure out which water kit to use for this unit. Ultimately I'm wondering if this lower unit will last all together. I'm looking for a original lower unit but am wondering if anything was modified to adapt this older lower unit. Appreciate any help.

 

[angelvigil03]

No Title

Here are some photos of what I'm talking about.

 

[Faztbullet]

A toon with a trolling plate??? some of the earlier units had a square shift shaft instead of spline so they may have switched them in lower unit

 

[angelvigil03]

Yeah I think someone was trying to race this pontoon ? So your saying someone might of just switched the lower casing ? Is there any reasoning why someone would do that ? I just bought this whole set up for $3500. Was planning on investing money into a new motor but the merc runs good. I'm planning on opening the lower unit it up soon and I'll post pics. Want service the impeller but not sure which one I need ?

 

[emckelvy]

It will take the same impeller as what would have been used on the 140hp: 47-89984T 4 or Sierra 18-3017.

One thing to note is that some of the older L/U's had a groove machined for a pin in the driveshaft, this is what would drive the impeller. Newer L/U's had a flat ground into the shaft and a regular impeller key used. This is the better setup, so if yours has the flat on the driveshaft, make sure to upgrade to a 28-8M0032834 key.

If the driveshaft has a pin-drive setup, make sure the impeller has a snug fit on the pin and doesn't rock around a lot.

If the pin looks worn, replace it, it's still available: 17-8M0034466.

HTH & G'luck..........ed

 

[angelvigil03]

Thanks for your help I appreciate it. Going to order the parts and open it up. Might need some help as I've never done it before.