| Also known as | D3548 |
| Diagram | Fig. 5 — CYLINDER BLOCK AND HEAD TR7RV · ref 46 |
| Subsystem | engine top |
| Listed in parts books | 1972–1974, 1976–1980, 1985 |
| Also fits (as replacement) | 1973–1974 · for 70-3309 |
O-RING ROCKER SHAFT SEALING TRI 650/750 - .500 x .070
Rocker shaft sealing O-ring, .500 x .070, for Triumph 650/750 twin cylinder heads.
This is the O-ring that seals the rocker shaft where it passes through the rocker box on Triumph 650 and 750 twins. The catalog specs it at .500 x .070, and it lives on the cylinder head, sealing off the rocker shaft spindle so oil doesn't seep out around the shaft bore. It shows up in the parts books under the CYLINDER BLOCK AND HEAD figures for TR6R, TR6C, and TR7RV twins.
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It's a small, cheap-to-replace piece but an important one if you're chasing an oil leak at the rocker box - a tired or hardened O-ring here is a common source of seepage on these heads. The older factory number for this same part was 70-3309, so if your parts book or an old parts bag shows that number, it's the identical item.
Given the low cost of the part, there's not much reason to run one that's showing age. Pull the rocker shaft cap or end plate and check the O-ring condition any time you're in there for valve or rocker work.
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