Where can I get viton o-rings for carb rebuild

[koolaid_kid]

That is the width of the groove, I moved the o-ring out of the way to measure the ID.

[Nessism]

That is the width of the groove, I moved the o-ring out of the way to measure the ID.

What is the ID of the O-ring seating hole the drain screw fits into?

[koolaid_kid]

Be an engineer, argh. I feel like all my engineering bits got toggled this morning.
I can't measure the width of the hole, it is recessed into the bowl and my caliper won't fit down in there.
If I go 3.5 ID, width 1.5, that will yield OD of 6.5, although it will be larger b/c the o-ring is stretched, correct?

[Nessism]

Be an engineer, argh. I feel like all my engineering bits got toggled this morning.
I can't measure the width of the hole, it is recessed into the bowl and my caliper won't fit down in there.
If I go 3.5 ID, width 1.5, that will yield OD of 6.5, although it will be larger b/c the o-ring is stretched, correct?

Yes, stretched. You are learning fast! Slight stretch to install, and about 1mm compression on the outside of the O-ring is just about perfect - although super small sizes can have less compression.

[koolaid_kid]

Thanks. I'm not usually this slow at picking up new concepts, but I guess I just had to get into an o-ring state of mind. The 3.5mm should work, the 3.8mm is definitely too large OD.
The part you selected for the air screw should work also, I went back and double-checked your work.
Thanks for the assist, it is much appreciated. And the best part - McMasters-Carr delivers to my door in one day.
And I cover all the carbs (6 times over) for the price of one set from the dealer.

[koolaid_kid]

Got the o-rings today. The 3.0mm ID, width 1.5 mm worked fine on the air screw. The 3.5mm ID, width 1.5 mm were too narrow in width for the drain screw, although the ID was correct. Now that I have new o-rings, I figured out how to measure them with my caliper, and I determined that I need 3.5 ID and width of 1.8 mm. McMaster-Carr does not list that size, so I sent them a request via email. Where else can I look?

[Nessism]

What's the problem with the drain screw O-rings? Is the OD too small thus the need for a thicker O-ring?

BTW, a -007 O-ring has an ID of 3.68mm and width of 1.78mm

Don't forget to check the dash number sizes as well.

[koolaid_kid]

What's the problem with the drain screw O-rings? Is the OD too small thus the need for a thicker O-ring?

Yes. Of course, since they are related, you could say the diameter is too thin so the OD is too small...
I've looked at American sizes, a -007 looks close. Robert Barr suggested that I also try a -006.
Edit - the -006 is too small. I just triple checked the screw, it measures 4.10mm, so that still gives me a bit of stretch. Sigh.

[Nessism]

Yes. Of course, since they are related, you could say the diameter is too thin so the OD is too small...
I've looked at American sizes, a -007 looks close. Robert Barr suggested that I also try a -006.
Edit - the -006 is too small. I just triple checked the screw, it measures 4.10mm, so that still gives me a bit of stretch. Sigh.

Why not -007?

[koolaid_kid]

Order placed for -007s. They should be fine. I had looked at them earlier and asked him if he had them in stock, but he did not.
Not sure why he suggested the -006s.