Zenith Float Needle Valve

[Rick Wall]

I am in the process of cleaning and rebuilding my 1962 Zenith 32 NDIX carburetors. They have 32-24 venturis. The original float needle valve has "125" stamped on it, the new valve in the kit has "175" stamped. My question is, will the "175" valve cohabitate well with the original spec venturis etc?

[Mike Wilson]

I just checked the Stoddard website and only one float needle valve is listed. I'm not sure why different numbers. What's important is setting the float needle valve at the proper height to set the float level itself.

Mike

[Alan Hall]

I believe the number refers to the size of the fully open needle valve. I also believe the original carb specs for a 356 called out a 125 needle valve. That said, the purpose of the needle valve is to fill the float chamber to the correct height and as Mike indicated, I don't see where a slightly larger needle valve (the 175) would not work fine if the float level can be adjusted correctly. The larger valve would take slightly more force to close against the pump pressure, so would probably tend to give a slightly higher float level and thus may require a slightly thicker washer under the needle valve to get the float level correct. The size specified is based on being able to flow sufficient fuel to keep the float bowl full during periods of maximum fuel usage, so you would not want to use a smaller than stock valve.

[Rick Wall]

Thanks Mike and Alan for your replies. Both the new and old valves appear identical on the outside other than the stamped numbers. Since the old ones still look to be in good condition, I may just reinstall them.

[Mike Wilson]

As long as the old ones move freely, I don't see a problem reinstalling them.

Mike

[Tim Berardelli]

Rich,

Float valve sizes are determined and sized by engine designers in the same manner that the jets for a particular carburetor are determined. A 40% increase in size will effect float performance. Stick with 1.25 needle valves.

[Mike Wilson]

Good info, Tim. So are only 175's are available in the kits?

Mike

[Rick Wall]

Tim, thanks for your comments.
So, while we are on the subject, the engine these carbs are going on is the original Normal block, with the exception of being rebuilt with new 86MM P&Cs, plus a "C" cam, and is yet to be installed and run. Will these 32-24s be ok with the larger bore and cam?

[Dick Weiss]

All Zenith carbs use the 1,25 float needles; The 1,75 float needles are for the Solex 40 PII carbs.
Don't exceed the fuel pressure of 2.8-3.0 PSI and adjust the float levels to the Zenith's lower gage line,
and turn off the petcock about 1/4 mile before shutting down the engine to prevent flow-over when hot.

[Alan Hall]

Rick, With the higher compression 86mm P&Cs and the "C" cam you have essentially made the engine into a super so I would recommend you change the venturies and jetting to the super or the "C" configuration.

[Rick Wall]

Dick, thanks for the valve clarification and advice.

Alan, I do have another set of Zeniths, with 32-28 venturis, but they look like they have had a hard life from the previous owner. I will inspect them closer to see if they are worth rebuilding.

Thanks, Rick

[Bill Lawless]

As long as the old ones move freely, I don't see a problem reinstalling them.

Mike

I have a float needle that moved freely, but it leaked and fill my oil pan with gas... My BAD for not turing off the gas valve, but I would still go new when ever possible..

[Tim Berardelli]

Rick,

What rebuild kit did you use? Two types are commonly seen on the market today-Walker, comes in a white carboard box, w/o any name/logo , and Karb Tune, in a plastic bag with a blue/orange ,white logo on the fold over cardboard top.

[Rick Wall]

Tim, I am using a blue and orange cardboard label Royze Karb-tun-kit, kits. Part # 616-108-902-00. I bought them probably 7-8 years ago. Other than the float valve concern, the kit seems to be ok so far.

Suggestions/insights on this particular kit quality?