never noticed this before

[opposedtwin]

In my efforts to try and use the OMC double fuel line on a mercury pressure tank, I started thinking why don’t I just swap out the different size nipples on the mercury set up with the same nipples as on the OMC set up and then voila!, I can use the OMC double line hose on the mercury motors. As I pulled the nipples off a mercury 2 lined tank to compare to the OMC nipples, I realized the nipples on the OMC tanks aren’t removable. OR ARE THEY? It depends on how old the fitting is! I have about 20 connectors but only one had removable nipples. Then I looked in the catalogs and it looks like they switched from the removable nipples to permanent ones in about 1955. (according to the RD/BigTwin catalogs anyway)

Soooo….where can I buy brass nipples that have a bigger threaded end and can thus be mounted onto the larger threaded holes of the mercury connector?

[chris-p]

You may be able to find adaptors, or have a machinist make them. Or just run 2 separate fuel lines, then join together with shrink wrap, using the Merc connector.

Would using an OMC fitting/line limit the fuel flow for the mErc? Seems like the fuel barb has a much larger ID.

[opposedtwin]

Not sure Chris. I thought about that too. I don’t know know if there was a reason Mercury fused two different dimensioned hoses together or not.

Have you ever seen an OMC connector with removable nipples like the one pictured? It has some sea horse green paint on it but no black anywhere. If it was green primer, you would think there’d be some black paint still on it as well.

[chris-p]

Yeah, I have a couple like that, the early ones. Like you found, most of them are fixed though.

A merc guy will jump in and know if the 3/16 line will restrict fuel flow or not. Ive never tried it, but you have to think, they must have enlarged it for a reason?

What about just making your own line, by using 3/16" for the air, and then whatever size the fuel barb is. Then running that through heat shrink tubing.

[chris-p]

What size is the larger fuel barb? 1/4" or 5/16"?

[kerry]

You say you have about 20 connectors. Is it worth sacrificing one to drill and tap for removable hose nipples? Perhaps using a more readily available hose barb? As far as flow, the OMC fittings flowed enough fuel for a Bigtwin. Just how thirsty are those gas guzzling Mercs, anyway? 🙄

If you have too many, AND not enough, you're a collector.

[amuller]

Hard to tell by looking, but it seems there many be enough metal in the fittings to drill and tap for 1/8" pipe thread, as Kerry suggests. If that works you will have future flexibility in hose sizes and the appearance change does not seem too drastic….

[opposedtwin]

quote Chris_P:

Yeah, I have a couple like that, the early ones. Like you found, most of them are fixed though.

A merc guy will jump in and know if the 3/16 line will restrict fuel flow or not. Ive never tried it, but you have to think, they must have enlarged it for a reason?

What about just making your own line, by using 3/16″ for the air, and then whatever size the fuel barb is. Then running that through heat shrink tubing.

I’ve thought about that too and it may come to that. Not sure what you’re asking, the ID of the bigger Mercury hose?

Kerry: not sure what you’re recommending. I want to find a 3/16 nipple with a bigger threaded end to fit into the Mercury connector, I don’t need to alter an OMC connector at all. I was only showing a picture of it because I think the ones with removable nipples are less common. (I believe the threaded end would need to be 5/16 to fit into the Mercury connector.)

Amuller: the OMC threaded nipples are too small to fit into the big threaded holes of the Mercury connector.

Scott

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