New packings & cups for hand primer pump

Post by **wesk** » Sun Feb 12, 2017 11:17 pm

How about this!

The stem flat at the knob end is held with a 5/16" open end wrench.

The nut that retains the spacer & cup is 3/8".

The nut that threads into the barrel is 5/8".

The large nut that holds the barrel in the dash is 1".

4x4M38 · Post by **4x4M38** » Mon Feb 13, 2017 7:58 am

So as I'm sure Wes knows I've run into a bit of a mess trying to cross the
leather packings to orings. ID and width arent an issue but OD is. I'm wondering if there is a different spec for sealing/crush for leather versus
say a Viton oring?

Post by **wesk** » Mon Feb 13, 2017 10:35 am

O-rings are generally manufactured to very close tolerances and prefer a shielded mounting environment that supports the O-ring in all directions. O-rings prefer tight chambers and groove mounting. The best way to mount an O-ring at the tip is in a groove so you would need to fabricate a short cylindrical spacer that will fit the threaded cup end and place a groove in it of the appropriate depth and width to adequately support the O-ring type and size you wish to us. That O-ring should be sized with an outer diameter that allows an interference fit inside the barrel, an inner diameter that allows an interference fit on the 3/16" threaded stub and a thickness that fills 99% of the groove.

I would suggest taking a look at Chevron type seals (V-packings) instead of O-rings for the 4 packings.

Here's an example in sizing:

V0037500625FF VP. 0.375 X 0.625 FEMALE V.PACKING - NEOFAB Details...
V0037500625FM VP. 0.375 X 0.625 MALE V.PACKING - NEOFAB Details...
V0037500625FV VP. 0.375 X 0.625 C.RING V.PACKING - NEOFAB Details...

You can view these at:

http://www.sealsourceinc.com/website/ca ... ing%203/16

They cost $2.93 each.

4x4M38 · Post by **4x4M38** » Mon Feb 13, 2017 1:38 pm

That's good info Wes.

The issue I see is the .593 bastard OD size of the packing.
Lost somewhere between 9/16" and 5/8".

I. I believe the cup is more conventional. That's why I was wondering
if it was weird like that due to the material being leather.

Take care,

Post by **wesk** » Mon Feb 13, 2017 1:47 pm

Did you actually find a listing for leather cups? Post it. Everything I have seen starts at 1" OD.

4x4M38 · Post by **4x4M38** » Mon Feb 13, 2017 4:42 pm

No, I was looking for a modern day product for the same service, Nitrile,
Buna-N....something one could actually buy.

Whatever is compatible with benzene and ethanol.

I don't know how you'd cut those cups in leather. The packing is
essentially a square o-ring.

You know, I think some water pump and valve applications even today
use leather.

4x4M38 · Post by **4x4M38** » Mon Feb 13, 2017 5:09 pm

There is a guy selling replacement cups for Coleman lanterns.
He is custom cutting them. I've sent him an email to see if he has
any interest.

4x4M38 · Post by **4x4M38** » Mon Feb 13, 2017 8:37 pm

Ha! He didn't say no! He'd like dimensions, and some
info on the pump. Other than cost to tool up he is
concerned about not being able to test the product.

I told him we could probably scare up some volunteers.
He's in Tyler. Maybe Cacti Ken could amble over.

On a related note is there a way Wes to snip the latter
portions of this thread and stick them onto a new post?
We've kinda wandered off the original question.

G740 · Post by **G740** » Tue Feb 14, 2017 6:39 am

I have a box full of NOS cups for the primer pumps.
John

4x4M38 · Post by **4x4M38** » Tue Feb 14, 2017 7:15 am

Thanks Wes!

Morning John!

Do you have the leather packings as well?

SRColeman · Post by **SRColeman** » Sun Aug 13, 2017 8:04 am

I now sell both the Leather Cup and 4 Leather Packings on eBay. (Hand made reproductions)

(If you guys are still interested!).

I made them from Wes K's diagram.

Cup part: 7037062
Leather Packings (4) part: 7097359

Just go to eBay and search: M38 and M Series Primer Leather

New packings & cups for hand primer pump

Cups

M38 and M Series Leather Primer Cups and Packings