OMC High speed nozzle gaskets

[outbdnut2]

I’ve done a couple of JWs by stacking two small O-rings together from a Harbor Freight O-Ring kit – I don’t remember the exact size they were.

Here’s the kit I have – will have to see if any in the kit will work on the next RD I take apart.
I’ve also found O-Rings in the kit that work for the top or various OMC driveshafts.
Dave
https://www.harborfreight.com/382-piece-o-ring-assortment-67554.html

[Steve D]

quote opposedtwin:

quote Mumbles:

Here’s an old thread about O ring replacements for the boss gasket.

viewtopic.php?f=2&t=2516#start_here

Mumbles, I think that thread gives the number for the o-rings that are replacements for the RD and Bigtwin models. I’m looking for rings for the other models like JW-FD.

Those are the ones I’ve been using for JW-FD. I could be mistaken but I thought I remember reading here that the RD and Bigtwin models didn’t use or need those? I didn’t see any pictured in one of the manuals I looked at from Garry’s DropBox.

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[opposedtwin]

Right Steve. The RD and Bigtwin models don’t list the part in their catalogs, at least the ones from the 50s anyway. The first time i see it listed in a parts catalog for an RD/Bigtwin is in 1961.
http://www.marineengine.com/newparts/pa … OMC0307778

[Steve D]

Oh, ok, I see the difference…they’re about 1/2 as thick as the other ones and some kind of cork/rubber? So did the earlier motors actually use one even though it wasn’t listed? Or was there a design change in the carbs requiring it?

[garry-in-michigan]

As I recall, they thought it was not necessary on large motors with a high speed needle valve. Any leakage could be adjusted for with the high speed adjustment knob. It became necessary as machine operators got sloppy. They had to put in the gasket when they went to fixed jets. . . 😀

[chris-p]

If you do not have an fixed high speed jet, the Big Twins and RDs do not need one, for the reasons Garry described, however, I still install one anyways. Having one is better than NOT having one any day of the week.

[Author]

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