Lower Units and Casting (housing) numbers 65HP '71 Merc

[turtle1173]

Hi,

I've been searching for a replacement lower unit for my 1971 65HP Mercury. Do I need to find a lower unit with the exact casting (housing) number that I have? Does this show what is compatible or not?

My housing number is 1623-4021 but I've seen several that were close yet not right on. Recently I found one that was a 1623-4930.

Can anyone help with this?

Thanks!

 

[Laddies]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

If it's a short shaft it's a A4 or the long is a A5
1623-5246A5 or 1623-7339A2 are short
1623-5246A7 or 1623-7339A25 are long numbers that number I cross it to.

 

[turtle1173]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

Laddies, thank you for the response.

Do you happen to know what other casing numbers I can be looking at that will be compatible with my motor? Anything other than 1623-4021??

Thanks,

Shane

 

[Laddies]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

Those are casting numbers the number on the casting won't have the A5 or what ever justs the first 8 digits but the long and short shaft engines use different castings back then. You could install a complete 6 cyl unit but the gear ratio is different

 

[turtle1173]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

Do you know if this one will work?

Casting number is 1623-5243

It is off a 1972 115HP Merc, which is supposed to be a 2:1 gear ratio.

Thanks!

 

[Laddies]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

If it's a complete unit it will work other than you will have to change the prop pitch to make it work

 

[Bondo]

Re: Lower Units and Casting (housing) numbers 65HP '71 Merc

Ayuh,.....

Those old 650s used a Gear Ratio All they're own,......

Other lower units will bolt on, but will be geared differently....