| Also known as | S1877 |
| Diagram | Fig. 4 — MANIFOLD AND TAPPETS · ref 5 |
| Subsystem | engine top |
| Listed in parts books | 1969–1971, 1974, 1976–1978, 1980 |
NUT INLET MANIFOLD FIXING
Small-hex 1/4-28 UNF nut that secures the inlet manifold to the cylinder head on Triumph twins.
This is the small nut Triumph used to hold the inlet manifold onto the cylinder head. It's a 1/4-28 UNF nut with a smaller-than-standard hex, which is worth knowing because a stock-size hex nut can be tight to get a spanner or socket on in that spot on the head. The catalog also lists it under the old S1877 number if you're working from an earlier parts book.
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You'll see this nut called out in the manifold and tappet figures, and separately in the inlet manifold figures covering both single-carb and twin-carb engines, so it's used whether the bike runs one carburetor or two. It shows up across catalog listings from 1969 into 1980, which tells you it stuck around as a common fitting item for a good while.
It's cheap enough that it's worth just replacing rather than reusing a tired one, especially if the old nuts are rounded off or corroded from sitting against the head over the years. Four of these secure one manifold, so check how many you need before you order.
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