| Also known as | E4603 |
| Diagram | Fig. 5 — CYLINDER BLOCK AND HEAD TR7RV · ref 16 |
| Subsystem | engine top |
| Listed in parts books | 1964–1965, 1967–1968, 1970–1971, 1974, 1976–1980, 1985 |
Inlet valve
Inlet valve for Triumph unit-construction twin cylinder heads, part number 70-4603 (aka E4603).
This is the inlet valve for the cylinder head, part number 70-4603, also known by the SRM aftermarket form 70-4603/SRM and the earlier E4603 designation. It shows up across the CYLINDER BLOCK AND HEAD figures for the unit-construction twins, including TR7RV, T140V, T140E, T120, T120R, TR6, and TR6R/TR6C listings in the parts books, so it's a part with a long run in the catalog.
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The inlet valve sits in the head and opens to let the fuel/air mixture into the combustion chamber on the intake stroke, then closes to seal the chamber during compression and firing. It's a wear item that lives in a hot, high-load environment, so pitting, seat wear, and stem wear are the usual reasons to replace it.
Given how many head variants this part number crosses in our records, don't assume one inlet valve fits every head off the shelf just because the number matches an old parts list. Check it against the head you're actually working on before you button things up.
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