Taper WFC Injector (SEC 2, Memo WFC 423 DA) is a 14 mm spark-plug-thread direct-to-chamber unit; .010 in slots are the QUENCHING circuit, not the field gap

Verified from headered scans "RE: WATER FUEL INJECTION SYSTEM / Memo WFC 423 DA": FIGURE 2-1 Taper WFC Injector Assembly, 2-2 Plug Housing, 2-3 Water Inlet Housing, 2-5 Clamp Nut Assembly. These are the Water Fuel Injector Ass'y (2-1), SEC. 2 referenced by the Fig 4-1 logic flow chart, fed from VIC Coil Ass'y 3-1 (SEC 3).

1. DIRECT-TO-CHAMBER PROVEN PHYSICALLY. Fig 2-2 Plug Housing specifies the mounting thread as "14MM 1.25 PITCH" — a spark-plug thread. The injector screws into the cylinder head. No manifold, no gas conduit. This is a hard discriminator against the <=422 generation, whose Gas Processor routes ionized gas "through air intake manifold (109) of Figure (3-31)". Consistent with the Project Binder 423-DA report statement that the new injector replaces the bulky resonant cavity unit and eliminates the special hydrogen conduit. Other 2-2 detail: T304 stainless, .7087 O.D.-24 thread, conical inner surface, .100 dia exit port, .176 dia inlet hole (polished surface), .6299 dia (16MM) x 2.675 depth c'bore cavity, .871 flat hex, 3.668 overall length.

2. POLARITY IS CONTINUOUS ACROSS GENERATIONS — NOT A DISCRIMINATOR. Fig 2-1 labels "POSITIVE CONICAL OUTER SURFACE PROBE" (centre electrode) and "NEGATIVE INNER CONICAL SURFACE" (surrounding cavity): centre positive, shell negative. Same convention as the early resonant-cavity work, where the inner element receives the positive potential via terminal and the outer element the negative (CA1234773A1 / EP0103656A2). Anyone using polarity to separate generations will misfile. Other 2-1 detail: taper resonant cavity chamber, quenching passageway, retaining check valve, water distribution cavity, insulation stem, ceramic or quartz insulator housing, stainless positive electrical probe, negative electrical tab, plug housing, water inlet housing, clamping nut, Delrin retaining cap, O-ring seal.

3. THE .010 INCH DIMENSION IS THE QUENCHING CIRCUIT, NOT THE POLARIZATION GAP. Fig 2-3 Water Inlet Housing specifies SIX quenching circuit slots at .010 W x .010 D, 60 degrees apart, 30 degrees displaced from centreline, into a .450 depth cavity; plus a .010 depth distribution cavity around 360 degrees, .0625 dia passageways, .125 dia ball seat surface for the check valve, 1/8-27 NPTF port, .7087 O.D.-24 thread, 3.55 length. .010 inch = 0.254 mm. The quenching circuit is a restricted orifice whose function is to prevent flashback (US 5,149,407); The Birth of New Technology gives "typically .010 or so" for the same quench dimension in the Funneling Effect passage. The taper cavity FIELD GAP is NOT dimensioned on Fig 2-1. Do not transfer Townsend/Td calculations done at 0.25 mm from the quench slot to the cavity gap without measuring the latter.

4. Fig 2-5 Clamp Nut Assembly: clamping nut T304 stainless, .750 O.D.-20 thread, .875 flat hex surface, .600 dia bore, .600/.380/.185/.100 stack; retaining cap in DELRIN, .690 / .600 (-.001) / .575 / .465 dia, .365/.200/.145/.020 stack.

CONSOLIDATED GENERATION TEST (priority order): (1) header field regex 'Memo WFC[ -]?([0-9]{3})'; (2) gas transport path — conduit/manifold = <=422, plug-thread direct injection = >=423; (3) resonant coil gauge — .004 Ga or smaller = 422 DA, .006 GA = 423 DA (primary is 30 GA in both, not a discriminator); (4) "copper may be used in place of stainless steel wire whenever applicable" appears only in 423; (5) frequency control — PLL + resonance scanning = WO92/07861 era, pot-set frequency with manual T2 compensation = 423 DA; (6) figure prefix, last resort, never alone.