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Herein I will use the term "Rubber Tipped" to refer to any type of carburetor valve needle that a soft tip.

Vapor lock and various other carb problems may be the result of rubber tipped carburetor needle valves.
They swell and deform.

Viton (not vitron) is a registered trademark for a series of synthetic rubbers made from vinylidene flouride and hexafluoropropylene and hence is related to the "teflon" family. I don't know if those materials are still used in inlet needles but they have excellent mechanical properties and are inert to gasoline and most solvents, alcohols included I believe. Though Viton was widely used for decades for inlet needles and was considered superior to the all-brass sets, perhaps something about modern gasoline other than ethanol has caused some incompatibility? Probably a phone call to Daytona Parts would give a definitive answer, but personally I'd also prefer an all-metal needle and seat.

Owen. Thanks for the correction on the spelling. I corrected spelling in the title to this thread.

I have a soft tipped needle that i installed 3 years ago in my 48 CHief. IT WAS NEW. It swelled and changed float setting by 100%. (1/4 inch vs 1/2 inch) and thus caused engine to run lean due to float setting too low.

This problem has also been varified by a well known Linkert carburetor rebuilder. According to him some of the claimed Viton tipped needles (offered in kits of recent years ) are not really Viton but someother type of rubber or compound.

I have another non-Packard vintage engine exhibiting the same problem and history.

Teflon is incredibly tough stuff, though not without its limits.

Given the sporadic reports from owners that the tips of the float needles had turned to goo, you have to wonder if the supplier had cut some corners WRT material quality.

Luckily, I have a few sets of genuine Rochester needle and seats set in all-metal, as original, for my cars.

According to him some of the claimed Viton tipped needles (offered in kits of recent years ) are not really Viton but someother type of rubber or compound.

That sounds a lot more plausible than Viton itself swelling.

In my other (non-Packard) life. I'm running experimental parts (modern materials) in my 48 Chief. The experimental parts are produced by popular and well respected suppliers of Indian Parts. The exp parts are NOT made be me.
I changed the original solid needle and seat that had ran superbly for 20 years and at least 20K miles. I changed it only because i was into the carb to install an experimental fibre float. Wanted everything as 'new' as possible for the R&D. I used a new 'rubber tipped ' needle and new seat streight from a sealed box from a well known HD aftermarket supplier for vintage HD. Same as Indian.

The original needle and seat (ran for 20 years and 20K miles) was also bought from well respected Indian dealer. However, i found that the area of that seat that contacts the float fingers was not slightly radiused and had worn the float fingers somewhat excessively.

The problem is that as Owen mentions, the fuels change so rapidly, and as BH mentions, supplier parts are mostly not tested rigorously enuf or corners are cut.

These problems are the root of many of our operational problems of the vehicles.


On a different subject. Pending a quick hand lap, i have found no valve seat recession using SS valves on stock Ductile iron cylinder seats. It's an Indian Flat head engine and runs extremely hot and higher rpm than the engine was designed to run. So i am less wary of SS valves now (when used withOUT hardened seats). However, i believe the suppliers SHOULD indicate that their Valves for the Packard V8 engine are SS in their parts book.

FRom the VI list:


From: liberty@npoint.net (Cotten)
Sender: VirtualIndian@yahoogroups.com
Reply-to: VirtualIndian@yahoogroups.com
To: VirtualIndian@yahoogroups.com



Robyn!

I posted an alert back in '05.

There are different designs of soft-tipped Linkert needles, but the most
common is shown "before-and-after" at
http://autos.groups.yahoo.com/group/VirtualIndian/files/VITON.jpg
Not only does the material swell (and therefore obviously not likely to be
genuine viton), an adhesive often oozes before the tip dislodges or
disintegrates.
Occasionally the tip is ground so far off-center that it fails to seal in
the first place.

The original needles were Monel metal.
We anxiously await a production from Fickau Prototypes, but it won't be
soon....

I hear they still have decent gasoline in Georgia.

...Cotten

Decades ago, I saw display ads in Cars & Parts magazine for a Grose Jet replacement needle and seat that used a ball in a conical seat. Ball and cone is a very sound principle for sealing; I recall DeVilbiss touting such a design feature for the air cap and fluid tip in their spray guns.

Perhaps the Grose Jet valve was only made for older carbs (prewar cars, brass era?), but it sounds like there's an opportunity, now, for later models.

Be careful about Viton and PTFE(Teflon) being related - that's true but they are not interchangable. Viton is an elastomer (rubbery) and will act as a seal. Teflon is not. (If you tighten a Teflon seal it just oozes to relieve the stress).

Personaly, i see absolutely nothing wrong with conventional SOLID needle and seat.

In addition to the Grosse Jet there was a a kind of donut shaped disk type (no needle) and seat that was offered in some kits during the 70's. I mite still have one in my junk pile somewheere. But i don't recall it as having any magical effects greater than convention solid needle and seat.