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Herald: Rocker Cover Breather


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Sorry if this has been discussed before.


I have a 1200 Herald engine, which has no rocker box cover breather. And the engine breather pipe that just releases everything down by the sump. Thankfully it's a very fume free engine, touch wood !


I would like to purchase an alloy rocker box cover from Moss, they say fit all 4 Cyl Triumph engines. On this cover there is a separate breather pipe though.


I plan to just get a stubby little filter/breather & leave it at that. Anything wrong with that approach ? Is there a better solution.


Anything else to watch, gasket the same, bolts the same etc ?


Thanks ... ;)

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Later, the crankcase fumes were vented into the inlet ducts, via a PCV valve (Positive Crankcase Ventilation) that limits the very high vacuum that is there at idle.

The OE ones can be found, or moderns use them too.

If there is a suitable pipe on your carb(s), then this a way to go, and could be done direct from the engine breather - look at the size of the drains between the push rods - there's free communication between crankcase and rocker cover.

If the hose from the breather is directed straight up, then oil vapour will tend to condense n the hose and run back down into the crankcase, a good thing!


Those tiny breather filters are too small and rapidly get saturated with oil.     If you can't burn up the fumes, then a "catch tank" is best.     Some people use just a plastic drinks bottle with the end of the breather hose stuffed in, but a proper alloy box with in- and outlets, and a drain, will allow that condensation to occur, and prevent the little filter on the outlet from getting swamped.   Costly, but most impressive in your engine compartment!



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if its the plain polish in their sale thats a good price


to go with it get a neoprene gasket from club shop  at £7.50  lasts  for lifetime 


if yours has a gauze filter filler cap you need to keep the  venting as there is open breathes a flow from top of engine down and out the low level crankcase  vent pipe  which is why the filler has a gauze and the tube is just open rocker stub up 


i would use  your short pipe idea and johns bottle.

dont seal the rocker stub up thinking its not needed 


as you are  going to seal with the new filler cap  from venting inwards you need to keep something in place 


Ive tried small filters on my Vit6 with this set up ...as john says they dont work well for long 



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