3.0L twin engines; differnent manifolds, interchangeable?

[PeterB26]

Hi,

I have twin 3.0L motors in my boat. Manifolds and risers were overdue for inspection, so I bought 1 manifold and 1 riser and started on the stbd side. The manifold looked good; replaced the riser and bought a second riser for the port side to do same. Today I noticed for the first time the port motor has the old style manifold with end plates. The Stb motor has the newer one-piece style.Don't know why I never noticed before because now that I see it I can't see how I missed it.

Both motors were renewed at a re-power simultaneously. I assume the port, being a counter rotation setup, was older inventory.

My question is when it is time to renew the manifolds do I need two different ones? Or can I change the older end plate style over to the newer style?

Carburetors, vacuum gauge fittings, drains, etc appear identical. Everything but the end plates and the aft lifting brackets appear the same, though the water passages to the elbow in the old style have "bridges" across them that are not on the new style, but the elbows and gaskets look identical.
But then up 'till today I thought the two manifolds were identical! LOL

Peter

 

[Bt Doctur]

there never was a reverse rotation inline 4. the only way is to have the Alpha GEN II CR or a CR unit from SEI
The head is what dictates the manifold.
i have the one without the endplate, pm me

 

[PeterB26]

Bt Doctur:
Thanks for your response.
Sent you a PM.... I think.....

I am aware that the only place a CR unit differes from the standard is the bottom of the leg and the cable connection to the remote shift. Just thinking that maybe the whole engine; transom unit; leg was inventoried as a "kit" and being CR there may not have been as much demand for them... so it sat in inventory longer. I don't know if that makes sense or not but I have no other good explanation as to why two motors purchased at the same time and installed at the same time woiuld be different vintage. Motors, transom units, and legs OEM Mercruiser, BTW....

It is not a pressing concern at the moment, but I'm curious as to interchangeability.

Peter

 

[PeterB26]

Here is my answer:

The manifold ***'y changed at motor S/N OM679999

The end cap style is listed as an obsolete P/N 806867A12 and is generally NLA except as old stock at some sites
It is superceded by P/N 860235A03 (no end caps)

So my port motor made it just under the cut off and it would take the one piece (no end cap) manifold as a replacement. So in a nut shell, yeah if I could get the old end cap style the two would interchange.... or more specifically I can put the new no end cap style on my port motor no problem.

Peter