Air Filter Canister Breather hole

[Wes]

Anyone know why the hole in the Air filter canister breather inlet is only about 1/8" versus the pipe from the rocker cover thats 1/2"?

[philthehill]

It reduces the suck - so that you do not get oil being sucked from the engine onto the air filter element and into the engine.
If your engine is in good condition then the hole can be opened up to 1/2". The small hole is a get around for worn engines.

[svenedin]

The other thing that reduces oil contamination of the air filter element is the baffle in the rocker cover. The pipe on the rocker cover has a metal baffle on the inside of the rocker cover to reduce liquid oil getting sucked in to the air filter. If this baffle is missing, the air filter can get soaked in oil which is also seen with very worn engines with severe blow-by.

Stephen

[Wes]

All good points. Reason for asking is that as i'm now in palliative care mode, to eek out the life of my engine, ive now routed the engine block breather (via a catch pot) to the filter too. Just thought the 1/8" hole may not be big enough now?

[philthehill]

Here is the restrictor as fitted to the rocker cover breather outlet.
The restrictor has been removed and is just below the breather vent pipe.
The rocker cover was fitted to a 1098cc MG Midget.

Rocker cover restrictor 2.jpg (90.11 KiB) Viewed 316 times

[svenedin]

This is the baffle that stops liquid oil being drawn up through the rocker breather pipe.

Stephen

IMG_3948.jpeg (1.81 MiB) Viewed 298 times

[philthehill]

There were several types of baffle fitted to prevent oil passing through the breather pipe

Rocker cover restrictor 1.jpg (90.36 KiB) Viewed 275 times

[Wes]

Thanks