| Also known as | E3698 |
| Diagram | Fig. 5 — CYLINDER BLOCK AND HEAD, T90 · ref 2 |
| Subsystem | engine top |
| Listed in parts books | 1964–1968 |
Cylinder block
Cylinder block for the 3TA and T90 engine, also cataloged as E3698.
70-3698 is a cylinder block, the piece of the engine that houses the pistons and forms the working core of the top end. In our records this part number shows up under the figure titles for the T90 and the 3TA and T90 cylinder block and head, so it belongs to those small unit twins rather than anything in the 650 or 750 range. The legacy factory number for this same part is E3698, which is what you'll find if you're working from an older parts book.
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As a cylinder block, it's the structural centerpiece the head bolts to on top and the crankcase mates to below, with the barrels bored to take the pistons. Beyond that, our catalog entry doesn't give us wall thickness, bore diameter, or finish details, so we can't speak to those specifics.
Given the narrow figure references, this looks like a part tied specifically to the 3TA/T90 family rather than something that crosses over to the bigger twins. If you're not sure which cylinder block your particular machine needs, give us a call and we'll confirm before you order.
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