Dual Zenith 32 NDIX jetting for a 1385.

[5500]

Been researching old threads for a few days and haven't been able to find anything specific on jetting. Have a set of PO2s (356 75 hp with 28mm venturis) that I'm considering adapting to PO3 specs (1600 normal/24mm venturis) for installation on my motor. Picked up a pair of Steffi manifolds. My question is what is optimal jetting for 32s with 24 mm venturis? All I can gather from multiple searches is stock 1600 normal (PO3) jetting will work. I'd like to try to dial in optimal jetting... will be running ~ 8.2:1 CR, stock WW valve sizes with a 3 angle valve job, an 010, WW performance cam, CSP Sebring style exhaust, and driving through a split gearbox with 165/15 tires. Any suggestions greatly appreciated!

[Jacks]

Start with the stock PO3 “1600 normal” 356 configuration
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Jack Staggs
Actual name

[Big_E_Deluxe]

I used the smallest NDIX jetting and venturi on my 1397cc engine. Works well. I have not attempted to go larger yet. I've attached a couple spec sheets for reference.

A good source of information can also be found at 356 Carburetor Rescue: http://www.356carburetorrescue.com/zenithpage.html

A good source for NDIX parts & jets: https://www.partsklassik.com/

Good luck

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Erik

1958 VW Beetle - "Max": https://www.thesamba.com/vw/forum/viewtopic.php?t=...highlight=
1959 VW Bus - "Hans" - Double Door Panel (sold): https://www.thesamba.com/vw/forum/viewtopic.php?t=746927
2014 Porsche 991.1 Carrera S

[5500]

Thank you Jack and Eric.... the list of specs I have isn't quite as comprehensive as yours.... appreciate it. Found a vendor on E-Bay who has a good inventory of parts for Zeniths at reasonable prices (ALFA1750's Carburetors Parts Store). Also has a large variety of Solex,Weber and Dellorto inventory as well. And discovered that the Unimog version of the Zenith has an adjustable throttle arm that will make dialing in CSP bellcrank linkage a lot easier. Its about $5 and available through a parts house in CA, Expedition Imports.

[Big_E_Deluxe]

I know enough to get myself in trouble, Jack is the expert. I think I've bought a few things from ALFA1750, no issues.

Make sure you checkout 356 Carb Rescue's web site. He has a lot of information on NDIX carbs. Especially sections from 356 work shop manual on NDIX's.

Keep posting your progress, would love to see how it turns out.
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Erik

1958 VW Beetle - "Max": https://www.thesamba.com/vw/forum/viewtopic.php?t=...highlight=
1959 VW Bus - "Hans" - Double Door Panel (sold): https://www.thesamba.com/vw/forum/viewtopic.php?t=746927
2014 Porsche 991.1 Carrera S

[Jacks]

If you don’t already have the complete “normal” jet set, I’d start with just the 24mm venturies and the 115 main jets and leave the other jetting as is.
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Jack Staggs
Actual name