Technical Which needle and seat to use.

I have a '51 Olds Rocket with an Offenhauser dual quad manifold for "square- base" carburetors. I was fortunate enough to be able to find (after several years of searching) a matched set of Rochester 4GC's from two stick-shift '53 Oldsmobiles. I am just finishing rebuilding one and am in the final stages of reassembly. The existing seats are brass and the present needles are solid steel. The needle that comes with the rebuild kit is a combination of steel and some composite (I think it's viton). Upon examination, the existing needles and seats seem to be in perfect condition. I seem to remember reading somewhere that the all-steel needles are superior to the composite ones.

I would appreciate hearing other's views on which is the best choice. Thanks.

 

Apparently Viton is fine for ethanol blends and is totally opposite of what I remember.

http://iqlearningsystems.com/ethanol/downloads/Ethanol & E85 Material Compatibility.pdf

 

Before viton , I seem to remember another type of rubber/ plastic was tried that would not work with ethanol .,.

 

bttt

 

My 2 1953 Olds WCFB's have Viton needles and have been on my dual quad unit for over 5 yrs without any problem. I use 1 oz. Sta-Bil with every tank of fuel. Problems can occur with excessive engine vibration with the metal on metal ones IMO. If you are using progressive linkage you need to get on it once in a while to all fuel to flow thru all 4 seats.

 

Thanks, Jimmy, that's the kind of information I was looking for.

I bought the rebuild kit about two years ago. Should the needle tip be viton?

I had no idea that WCFB's were available on '53 Oldsmobiles. I always thought they used Rochesters; 7005700 for stick shift cars and 7005600 for Hydra-matic cars. I think the Dynaflow equipped cars used a 7006250. I have examples of the first two and can't tell the difference.

 

OK, i'll try this one more time. Right now, I am leaning on using the new needles and seats from Jimmy"s information.

 

New and improved , somewhere in the early 60's, Jiffy Kit touted their new and improved rebuild kits with Viton needles. Viton needles have been around a few years now.

 

The neopreme fuel valves, regardless of what name is on the box, come from either Vernay or IER. Both offer excellent quality valves.

Early neopreme valves (late 1950's - read new old stock) were sensitive to ethanol. Current valves don't seem to have a problem.

New old stock steel valves can rust, ethanol or not.

There are still some individuals that believe the steel is superior; so we still offer the steel as an option, but suggest the neopreme.

Jon.

 

I use these when they have them for what I am working on.
They flow slightly more than others.
https://www.daytonaparts.com/daytona-carburetor-float-valve.html

 

Thank you gentlemen. Since I don't think I have to worry about fuel flow on a 324" Olds (1/8" overbore) with two 4 BBL's, I think I'll go with the viton tipped needles.