| Also known as | H200 |
| Diagram | Fig. 6 — CYLINDER BLOCK AND HEAD · ref 6 |
| Subsystem | engine top |
| Listed in parts books | 1960–1962, 1964–1971, 1974, 1976–1980, 1985 |
Tappet block screw
The locking screw that secures the tappet guide block in the cylinder block on Triumph twins.
This is the small screw that locks the tappet guide block in place in the cylinder block on Triumph twins. It's a common fastener across a long run of Triumph parts books, showing up in cylinder block and head figures for machines like the 6T, T90, T100, T110, T120, and 3TA/5TA lines, as well as manifold and tappets figures. The older parts book form of this number is H200.
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The tappet guide blocks sit in the cylinder block where the pushrods reach up to the rocker gear, and this screw is what keeps the block from working loose or rotating in its bore. It's a small part but an important one to check when you've got the cylinder block apart for valve or pushrod work.
Given how many different cylinder block and head figures this screw turns up in across Triumph's unit and pre-unit twin lineup, it's worth having a couple on hand any time you're doing top-end work, since these can get chewed up by an impact driver or a worn slot over the years.
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