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1978 omc 400 died

T

thedoubledeuce

New member
I have a '78 OMC 400, in which the upper unit seized, and the lower unit has been repaired from freeze damage. I purchased a "new to me" 400. The "new" unit is an '86. Are they interchangeable? Will I need anything to make the swap? Any help would be AWESOME.

Mike
 
Re: '78 omc 400 died

1985 was the last year for the 400. 1986 was the first year for the 800. If your sure the ( new ) one is a 400 and the gearing is the same it should work. Is the new drive off the same size motor ?
 
Re: '78 omc 400 died

400 is for the 4 and 6 inline motors. 800 is for v-6 and v-8. 86' was for the first year of the cobra.

However i have a 86' 400 stringer and i have seen a few boats that are 87' that are stringers. Every thing up to the cobra is considered "Stringer drive"

Soo have pics ? Reason i ask there are electric stringer drives, hydro-mechanical drives, and fully mechanical drives, and of course cobra and king cobra.
 
Re: '78 omc 400 died

Hi guys, thanks for responding so quickly. I have been swamped here with work, trips outta town, school and family, that I have not been able to get time for the boat. I will get pics asap.

Here is some more info about the boat. '78 Silverline Hilo 16VBR, 140hp gm 181 cid (3.0). The outdrive is a 400, it is marked on the top of drive, and if I am correct it is the hydro mechanical. Drive model #:981110 Motor model #: 990245D. Hope this helps.


Thanks again.

Mike
 
Re: '78 omc 400 died

any lower newer than 1981 would be full mechanical and not compatible with your shift converter etc.

the rectangular zinc next to the idle relief holes on the lower is how you can tell it's full mech.

your 1978 would not have this zinc being hydromech

You can use any 1978-1985 400 or 800 series upper if it has the right gears in it. it's only the lower where you need to be careful of generation.

There were 2 ratios used behind the 400 series, so with prop swaps etc you might be able to use an upper with different gearing
 
Re: '78 omc 400 died

dunno... I get them from a guy behind the Keswick Tim Hortons.... just ask for a "double double"

:)
 
Re: '78 omc 400 died

OK, so the upper unit is interchangeable. What would I need to replace to use the lower unit, shift converter... I am new to I/Os. I have only ever owned OB's.

Mike
 
Re: '78 omc 400 died

yes, lower complete with its shift cable, shift converter from the newer boat with the ESA switches on it, and then you would need the ESA module and associated wiring.
ESA = Electronic Shift Assist. It's a module that stumbles the ignition while you shift, primarily to help the dogs in the lower unit disengage so you can shift to neutral.
 
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