Viton Needle and Seat

[Original Smith]

I bought one of these and put it on my NH. It worked for one day. It was on my car for the Western National tour in San Diego, and I had to get pushed to start the car every time. What a problem! The car always started every time before I put that POS on. I believe the gasoline in California is attacking the viton. I took it apart and it looked ok, and put it back on. Same problem. Today, I put a NORS original style on the car and it started on the first pull. No more of those Viton's for me. The original style is good enough, and I've been running NH'S for over 60 years on all of my cars.

[Professor Fate]

I had a sticky one. Fixed it by polishing the non viton
covered sides so it glided effortlessly from closed to open.
Problem solved. Used a dremel with polishing tip and maguire
mag/chrome polish.
The viton tip was gently wiped, and I swabbed a q tip with brake cleaner
in the seat where the viton seats in the carb. I let the brake cleaner dry and evaporate
Before reassembly.

[Moxie26]

Good work Larry... And I agree with you 100%. I have used the original needle and seat and a dual ball valves for many years with no problems. Few years ago a friend had a problem where the car would start and then conk out about 20 seconds later... And it was because the viton tip needle got stuck.

[Steve Jelf]

I had a sticking viton seat too. Going back to original fixed that.

[Adam]

Many needle-seat issues are caused by excessive use of fuel valve lubricant. If even a speck of that stuff gets loose in the fuel system it can stick float valves fully or partially open or closed and fuel doesn’t dissolve it. Not a problem in a pressurized system, but can be a big issue in a gravity flow system.

The root cause may not be the part itself…

[speedytinc]

As is typical with most, many or all repop parts, they just miss the mark for being correct & functional out of the box.
Same situation here.
The seat edge was/is razor sharp. (I cant say what with current production because I drill out the seat to OEM size plus for correct/hi volume fuel flow.)
That sharp edge bites into the viaton tip. Especially if any upward pressure is applied while adjusting the float. The fix is to place a new ball bearing into the seat, with a lite tap to reshape the seat edge. (about a 5/32")
Of course that has not solved the problem of fuel starvation @ high demand from a way to small inlet hole.

Right out of the pack I drill the passage to 1/8" in my lathe. That process adds a slight chamfer. I confirm the seat with a vacuum test before & after install.
Sounds like a lot to go thru for a leakless carb?
I have restored scores of NH's this way for myself & customers. No drips, no sticks or performance issues from anyone. (With a clean fuel tank)
Any needle & seat is susceptible to dirt/trash/foreign stuff from the tank, but it is clearable.

[JBog]

Many needle-seat issues are caused by excessive use of fuel valve lubricant. If even a speck of that stuff gets loose in the fuel system it can stick float valves fully or partially open or closed and fuel doesn’t dissolve it. Not a problem in a pressurized system, but can be a big issue in a gravity flow system.

The root cause may not be the part itself…

How common is this in general? I just yesterday smeared a bunch of fuel lube on my carbs valve.

[speedytinc]

Its common if you are not careful with the lube.
I have seen strings of teflon tape get between the needle & seat.
A hair will do it.

[J1MGOLDEN]

I had a hair from the felt gasket get caught in my needle valve.

They have improved gaskets now with no hair.