Thread Size for OMC Waterpump Screw–need Helicoil

[raglover]

I need to put a helicoil in one of my OMC lower unit water pumps. 1957 35 hp model. It is the standard flat head screw used in all of them.

I forgot to bring it with me today to measure the size and thread so I could pick up the parts at Fastenal. Does anyone know it by heart?

I would guess it is a 10-32?

Thanks,

Allen

[RICHARD A. WHITE]

Maybe 10-24, but I don’t have one in front of em either

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[fisherman6]

I’m pretty sure it’s a #10 screw but I don’t remember it being a fine thread. Hopefully someone knows for sure but I’m thinking it’s #10-24 UNC. I certainly could be wrong. Dan Anderson would likely know from memory.
-Ben

OldJohnnyRude on YouTube

[wedgie]

3/16 (#10) – 24 and 1.165 long including head

[1946zephyr]

When you put that heli-coil in, make sure the end of it is flush, or just below that flat surface, because your waterpump will no work correctly if the wear plate is not sealed to that surface properly.

[1946zephyr]

Yea, that would be a 10-24 thread, if it measures 3/16" nominal size is technically .190

[wedgie]

Yeah, just thinkin’ like an amateur carpenter here . 😕 😆

[1946zephyr]

It’s all good. You are correct though. Most #10 screw sizes measure out in that size. Some even go as low as .180

[raglover]

Thanks Everyone!

[Author]

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