Zenith Accel. Pump Plunger Assy. Sold In Classifieds: Feedback?

[Brian R Adams]

Has anyone tried the Zenith 32NDIX accelerator pump plunger assembly, or just the leather cup (skirt), sold out of Florida in the Classified section? Looking for feedback.

Brian Adams

[Ron LaDow]

Has anyone tried the Zenith 32NDIX accelerator pump plunger assembly, or just the leather cup (skirt), sold by out of Florida in the Classified section? Looking for feedback.
Brian Adams

Brian, how about a link? I looked at a couple of pages, but give us a hint1

[Brian R Adams]

Ron,

Here you go:

Leather cup:
https://porsche356registry.org/classifieds/22656

Plunger assembly, complete:
https://porsche356registry.org/classifieds/15384

[jay abrams]

Bought a couple 2 or 3 years ago. As advertised. No complaints.
Jay

[Ron LaDow]

I've never swapped the cup, but the assembly shown with the cup looks short.
There are (at least) two lengths of pump pistons; the one in our 32NDIX carbs and a shorter one found in some 36NDIX carbs. Counter-intuitively, the shorter one delivers a greater volume and there is insufficient adjustment in the linkage to reduce it to what 356s require. BTW, at least some of the short ones have an elastomeric cup which sure works more reliably than the leather part.
Can't say anything about the complete part offered; never used them.

[Brian R Adams]

I've never swapped the cup, but the assembly shown with the cup looks short.
There are (at least) two lengths of pump pistons; the one in our 32NDIX carbs and a shorter one found in some 36NDIX carbs. Counter-intuitively, the shorter one delivers a greater volume and there is insufficient adjustment in the linkage to reduce it to what 356s require. BTW, at least some of the short ones have an elastomeric cup which sure works more reliably than the leather part.
Can't say anything about the complete part offered; never used them.

Ron, are you familiar with the plunger assemblies included in Zim's rebuild kit? Or can you recommend a source for same?

[Ron LaDow]

Brian,
Nope. Bought much 'stuff' from Al over the years with no gripes, but not that and have no knowledge of that offering.

[Dick Weiss]

I agree w/Ron's findings; But the later plunger has a tiny hole in the brass part which will pass some fuel to releve (?) excessive fuel during its stroke (haven't look @ one
if it's the shorter or longer plunger. If the leather cup isn't worn excessively, you can lightly stretch the cup's spring (or unscrew it's joint--if the carb;s bore isn't scored) to increase the cup's contact. Also, adjusting the link rod and connecting to the arm's different holes may lessen the stroke(?).
However, maybe better to just replace the complete plunger.

[Jim Kaufmann]

Have no experience with the pumps offered in the classifieds, but can comment on these Modern Zenith pumps, they are a problem for us at 356 Carburetor Rescue. Found the leather to vary in shape on these new units, in many cases after sitting in the carb with fuel overnight, the pump will stick in position and stop the function. Using a very light touch of the leather on a grinding wheel and slightly reducing the diameter, the pump will function again. When doing this just be careful not removing to much material, you don't want it to just drop into the pump bore with no resistance. Then you would have to start again with another pump.
This is not the case with all the new pumps, some work fine right away, others will stick, and sometimes will never work correctly. In extreme cases where we can't get a new pump to work, we have a limited number of original pumps that were lightly used units, when using them, the problem always goes away.
Hope this info helps anyone encountering the same issue.
Walker Products is the suppler of the pumps we use, only source I've found. Does anyone know of another manufacturer of Zenith pumps?

Jim Kaufmann
356 Carburetor Rescue

[Brian R Adams]

BTW, at least some of the short ones have an elastomeric cup which sure works more reliably than the leather part.

Ron, I bought a pair of elastomeric cups (came with backing washers) from SwissArmyVehicles.com some years ago. But I haven't yet attempted to swap out an old cup for one of these, as it seems like I might need to destroy the OEM assembly trying it.

[Brian R Adams]

Jim, thanks for the comments. SwissArmyVehicles.com sells pump assemblies w/ leather cups, and also the elastomeric cups I pictured elsewhere, but the assemblies I bought are the too short (I believe for 36 NDIX) so I couldn't use them.

I will be contacting you at CR.

Brian

PS
NLA Ltd offers a pump assembly w/ leather cup:

http://www.nlaparts.com/store/zenith-ac ... -2743.html

[Jim Kaufmann]

Brian, Yes, I had picked up a couple of their pumps years ago and they are the short version giving to much squirt, probably fine in a 36NDIX. Trying to replace the leather on a pump as you say will destroy the metal parts, also after all the fussing to do such a repair, you'll still be stuck with the fit of the leather in the bore. Do feel it's best to start with a new pump and tweak it to work.

Jim

[Ron LaDow]

[...]Found the leather to vary in shape on these new units, in many cases after sitting in the carb with fuel overnight, the pump will stick in position and stop the function. Using a very light touch of the leather on a grinding wheel and slightly reducing the diameter, the pump will function again.[...]
Jim Kaufmann
356 Carburetor Rescue

You can get more of them to work yet if you hone the bore; there is a 'bead hone' small enough to fit in there and a light honing would up the success rate as much as grinding the edge of the skirt would.

[Brian R Adams]

You can get more of them to work yet if you hone the bore; there is a 'bead hone' small enough to fit in there and a light honing would up the success rate as much as grinding the edge of the skirt would.

Makes sense, think I'll do that. The bore seems tapered top-to-bottom, so that complicates hone selection a bit, but only the bottom half or third of the bore takes needs to seal.
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[Brian R Adams]

Bought a couple 2 or 3 years ago. As advertised. No complaints.
Jay

I hadn't before, but I now notice he's selling the Walker, as apparently (but not specified) are NLA and Zim's.
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