| Also known as | E4676 |
| Diagram | Fig. 5 — CYLINDER BLOCK AND HEAD, T90 · ref 5 |
| Subsystem | engine top |
| Listed in parts books | 1964–1969 |
INLET TAPPET GUIDE BLOCK 66-68 TRI 500/650
Inlet-side tappet guide block that houses the cam follower in the cylinder block on late-60s Triumph twins.
This is the inlet tappet guide block for Triumph twin-cylinder engines, sitting in the intake side of the cylinder block where it houses the tappets (cam followers) and keeps them aligned so the pushrods can properly meet the radiused ends of the tappet stems. Catalog records for this number span 1966 to 1969 and it appears across cylinder block and head figures for a range of Triumph twin-cylinder models, as well as an oil pump and tappets figure. It's also known by the older E4676 designation, which is the same physical part under the legacy part-numbering system.
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Good alignment matters here — the guide block has to sit true in its bore so the tappet doesn't bind or wear unevenly. If you're rebuilding a top end from this era, it's worth inspecting the bore in the cylinder block itself along with the guide block, since wear in either one can throw off pushrod contact.
Give us a call if you're not sure whether this matches what's in your cylinder block — there were different iterations of this guide block used across the years, and matching the right one to your engine keeps things running true.
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