| Also known as | E4746 |
| Diagram | Fig. 6 — CYLINDER BARREL, PUSH RODS AND TUBES, TAPPET BLOCKS · ref 12 |
| Subsystem | engine top |
| Listed in parts books | 1964–1974 |
SEAL CUP, PUSHROD TUBE
Seal cup for the base of the pushrod tube on unit-construction Triumph twins, helping keep oil in at the cylinder block and head.
This is the seal cup that sits at the base of the pushrod tube, where the tube meets the crankcase on the cylinder block and head. Its job is to hold the sealing washer in place and keep oil from creeping out around the pushrod tube as the engine runs. It's a small part but an important one for keeping the top end dry underneath the tube.
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In the parts books this cup shows up across the cylinder block and head figures for the 3TA and T90, the T100S and T100C, the 6T and TR6, and the T100R and T100T, so it's a common fitment across several unit-construction twins from the mid-to-late '60s catalog runs. You'll also see it listed under its older reference E4746, which is just the earlier form of the same 70-4746 number.
These cups wear out or crack with age and heat cycling, and a worn one is a common source of a pushrod tube that seeps oil even after you've replaced the rubber seals themselves. If you're doing a top end reseal, it's worth checking these rather than just swapping the O-rings and hoping the leak goes away.
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