Author Topic: M32 Spring Loaded Pushrod Tubes  (Read 318 times)

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Offline Hamwic

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M32 Spring Loaded Pushrod Tubes
« on: 09 Oct 2021 at 17:47 »
Hi All,

Annoyed with the constant loosening of the M32 pushrod tubes, and the questionable joy of trying to re-tighten them  on a hot engine by the roadside, I decided to come up with something a bit more compliant.

At the moment easily telescoped steel tubing seems to be in short supply, so I have made some spring-loaded tubes in alloy. These also have an alloy ring to compress a high temperature O ring that hopefully will staunch the flow of rocker box grease. The ends of the tubes are gently tapered to fit the recesses in the tappet guides and head registers.

Once the tappets are set, the tubes are extended and and a circlip is slid up the tube, so compressing the spring and seal, and locking in a shallow groove to keep it all in place.

The OD of the outer tube is 22mm, bored to 17.6mm. This to suit the available springs -  nominally 18mm ID x 30mm long in 1.5 wire.  The OD of the inner is turned down to a sliding fit within the outer, and the ends lightly tapered inside and out. The outer tube has a recess for the O ring. A small back-up ring is made from spare outer material, and a ring groove machined to match the O ring.

It all goes together as seen in the accompanying picture, and so far seems to have done the trick.

Unfortunately on the way home, I noticed the sight glass had filled up, but oil didn't seem to be getting into the engine, so attention must now turn to the pump and feed circuit.

There's always something else to do!

Cheers for now