MTFCA Forum

I don't know about other states, but the gasoline sold in California softens the tip, and causes it to stick to the seat. Too bad for us!

I have not had this experience. The ones in my roadster PU have never stuck.(2 carbs) I dont shut off the fuel ever.
I have not removed one from a used carb that was any softer than new. Viaton is supposed to be compatible with the poison we use as motor fuel.
I have seen ones that stick because of a sharp edged seat, especially when the float was re-bent putting pressure on the tip.
Past batches had a sharp edge & burr.
I redrill the seat hole larger to bring the hole up to the correct, OEM size & add a small chamfer. All carbs pass multiple suck tests.
I have noticed a failure of the test traces back to the seal of the seat in the carb body typically.

As an aside, I recently reworked a new, repop NH. The threaded hole was not straight & the seat wouldnt seat square in the body.

I would recommend running the carb dry if you don't run it every 2 months @ a minimum. 1) to prevent varnishing. & 2) To keep the volatiles from evaporating. (may be a Ca. blend issue.)

My problem in the midwest is that the needle and seat will work perfectly...for a while. Then it will start leaking and the only way to stop the leak is to replace the needle.

rondupree wrote: ↑

Mon Jul 29, 2024 12:47 pm

My problem in the midwest is that the needle and seat will work perfectly...for a while. Then it will start leaking and the only way to stop the leak is to replace the needle.

Look carefully @ the tip. Is there a cut? small dirt flake?
Have you carefully wiped the tip? Do not rub on your pants like a pencil eraser, that will wear away the viaton.
Have you tried twisting a pointed wood dowel, like a sharpened chopstick into the seat to un-varnish?

It would be good to know exactly why you are having uncharacteristic? problems.

Steve Jelf wrote: ↑

Mon Jul 29, 2024 1:23 pm

I had a problem with Viton tips sticking too (not in California). The answer for me was going back to an original valve. The current repops are notorious for fuel starvation due to being drilled undersized. Try a Scott Conger valve, which is made correctly. I would show you a picture, but I can't do it on this computer.

I am very familiar with Scott's modifications.
Does that modification Improve/prevent the sticking problem?

I have found that the non viaton needles will seep a little best case.
Are you getting a 100% seal with no weeping or wet carb?
The last steel tipped needles I tried were ground off center. Tapped to seat, they worked fine, but eventually turned & leaked. Drove me nuts until I figured it out.
I have been using modified viaton units exclusively since.

I bet the leaky ones are NEOPRENE not VITON.

Grose-Jet inlet valves are still available,....any problems ?

Never had a leak with a Scott Conger valve. Never had a fuel starvation issue with low fuel either. The valve on the right is Scott's "Full-flow" valve. The valve makes a NH perform like it's supposed to.

I have found the Gros Jet does not let enough fuel in for hill climbing and will stall with open throttle. I use a steel needle and turn off the gas but do not run the bowl dry afterword. When I park in the garage for overnight or longer, I put a tin can under just in case it drips. No problem.
Norm

Since folks read this stuff...

Viton made right, and surface finished 'right' and at the 'right' hardness is a good product for resistance to gasolines and the bio fuels even in an on/off application...however...wipe it with something like MEK or other solvents and its internal properties go 'poof' in many ways even tho it looks the same. I'm not sure what the right surface finish is...and I'm not sure what the 'right' ShoreA hardness is...but it should be available on the web somewhere.

I have had problems on at least two cars. Both times the needle sealed very well for a long time, then started leaking. I tried removing the needle and let it dry. I tried wiping it off as best I could to remove any debris. No luck. Both episodes were 5 years or so ago.

Looks like a cleaned up original NH inlet valve is the answer for consistent level and positive shut off.