| Also known as | B291D, E2256 |
| Diagram | Fig. 1 — CRANKSHAFT AND CONNECTING RODS · ref 37 |
| Subsystem | engine bottom |
| Listed in parts books | 1960–1962, 1964–1969 |
Breather valve spring
The breather valve spring behind the rotary breather disc on the crankshaft, part of the crankcase pressure release system.
70-2256 is the breather valve spring, a small spring that sits behind the rotary breather disc on the crankshaft assembly. It's part of the crankcase breathing arrangement that lets excess pressure vent out of the engine as the crank spins, and it's found in the crankshaft and connecting rods section of the parts book. This one shows up under the older B291D and E2256 numbers as well, so if your book or an old parts bag has either of those stamped on it, it's the same piece.
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It's a simple, inexpensive part but it does real work keeping crankcase pressure in check, and a tired or broken spring here can lead to oil being pushed out where you don't want it. Catalog appearances for this one run from the mid to late 1960s, across a good number of listings, so it was a long-running fitment in that era.
Worth keeping a spare on hand since it's small and easy to lose track of when you've got the timing cover off. Give us a call if you want to confirm which breather disc and spring combination pairs with what you're working on.
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