Carburetor Baffle Plate

[Solitude 69]

A bit of a story here but.... I have a 1969 Mercuiser 160 HP straight 6. In trying to find a replacement intake manifold I found......none to be found. So I bought a "log style" made by Barr Marine which fits the 1970 and later Mercuiser 165 which as far as I can tell is identical dimensionally in every way such as block, cylinder head etc. This new manifold is quite different than the 1969 in that it requires an alumninum carburetor adapter plate that first bolts to the manifold, then the carb bolts onto the adapter. Not to mention other things, like it also requires a special aluminum bracket that supports and attaches the throttle cable. Now, in researching the carb adapter plate I see in some pictures that there is a separate aluminum baffle plate that bolts to the underside of the carb adapter plate. You can see it in the pic below. My question is, is this needed and if so, what is the purpose? I speculate that it helps to balance intake flow into the manifold by restricting flow a little bit to the two middle cylinders. If I can't find one I will either make one as close as I can based on pictures or just plug the holes in the carb adapter. Thoughts? Has anyone run into this before? Thanks

 

[Scott06]

Would generally assume Merc didn't add unneeded parts.. Looks like the later manifold uses what looks like a 4 bbl to 2 bbl adapter plate... I would only think the baffle hanging down directs the airflow to the closest cylinders as they would have a really short intake runner length? Hard to say but would think you are best off including it.

if I didn't have one you can try it out with out but keep an eye on the spark plugs in case it leans out some of the cylinders. if it runs ok and plugs have the right color leave it alone.

On my older boats 3.0, which is the little brother of your engine, I always had the two end cylinders having a nice light ash grey color and the middles ones being black and rich looking. Would assume this is only worse on a straight six of similar design.

On parts diagram it looks like there are two different top plates/carb adapters (cant find the baffle in dwgs) one with 4 bolt holes and one with six...

When ever you get into mixing and matching years and parts always a little fun involved...

 

[Solitude 69]

Thanks for the reply Scott. This 1969 has been a challenge for a few years now. Thank goodness for the internet. It's amazing what you can find. I can remember looking over microfiche at the marina parts dept 35 years ago and paying thru the nose for everything!