Stewart Warner, 2-1/8 inch, mechanical — and the needle still reads where it should.

There's a reason Stewart Warner gauges ended up in so many hot rods and race cars: they looked right and they worked. This is a 427220 water temperature gauge, the 2-1/8 inch mechanical version — black face, chrome bezel, and a capillary tube running to a brass sensing bulb.

Mechanical means there's no sender, no wiring and no voltage to worry about. The bulb, the tube and the movement are one sealed system: the bulb goes in the water, the tube carries the pressure, the needle reads it. It works on any vehicle, any electrical system, or none at all.

The capillary measures 72 inches — the longest of the three lengths Stewart Warner catalogued this gauge in (48, 60 and 72 inch, catalogued as 82305, 82306 and 82307 respectively). This is the 82307. If you're running the tube from a dash gauge back to a water neck, through a firewall, or into anything with a long or awkward routing, the six-foot line is the one you want — and it's the one that turns up least often.

It has been tested, and the seller is being straight with you about how. The bulb was put into boiling water and the needle read just past 210°F — where it should, since water boils at 212. It moved smoothly and returned as expected. That's not a calibration certificate, and it hasn't been checked against a reference gauge, but it does tell you the system is still sealed, the movement is alive and the reading is in the right place. On a gauge this old, that's the whole question.

🔧 Features and Details

• 🎯 Stewart Warner part number 427220, printed on the face
• 📐 Catalog no. 82307 — the 72-inch capillary version, the longest Stewart Warner offered
• 📏 2-1/8 in. face — the common vintage and custom dash opening
• 🌡️ Mechanical capillary gauge — no sender, no wiring, no voltage required
• ✅ Tested: read just past 210°F with the bulb in boiling water — needle moved smoothly and returned as expected
• ✨ Presents as near-new — clean face, clear glass, bright bezel
• 🏁 Universal fitment — works on 6V, 12V or any system, because it doesn't use one
• 🔨 Mounting bracket included

🚗 Known Fitment and Applications

• Universal. Fits any vehicle with a 2-1/8 in. gauge opening and a suitable port for the sensing bulb — a water neck, thermostat housing, head or manifold boss.
• Because it's mechanical, it's electrical-system agnostic: 6 volt, 12 volt, positive or negative ground all work, since the gauge doesn't use vehicle power
• 72 inches of capillary gives six feet of routing — enough for a rear-mounted engine, a long firewall run, a dash-to-water-neck route in a full-size car, or anything needing slack
• Traditional hot rod, kustom, race car, custom dash and period restoration use
• Confirm the thread on your intended port matches the bulb fitting before ordering

Additional applications beyond those listed may exist.

✅ Condition Summary

Used original in excellent condition — it presents close to new, with a clean face, clear glass and a bright bezel, though it can't be confirmed as unused. Function tested: with the bulb in boiling water the needle read just past 210°F, moving smoothly and returning as expected. Water boils at 212, so that's the reading you'd want to see. It has not been checked against a reference gauge, so treat it as a demonstrably working gauge rather than a calibrated one. Sold as-is on that basis. Please look through all the photos.

📋 Buyer Notes

This came out of a garage lot purchased from a retired Southern California restorer who's stepping away from the hobby. Look through the photos before buying — the face, the bezel, the capillary tube and the sensing bulb are all shown, and the photos are part of the description. Confirming the bulb fitting suits your intended port, and that the tube will reach where you need it, is the buyer's responsibility — measure your routing before ordering. Other applications may exist beyond those described. Function tested, accuracy unverified, sold as-is. Questions are welcome before purchase. If you're building a period dash, there's more in the store worth a look.