breathers?

Post by **superchargedfool** » Tue May 05, 2009 12:54 pm

My moggy has 2 breathers. Timing chain and rocker box.

I have always had my timing chain one plumbed to the carb and the rocker one to a catch can.

What is the consensus of opinion from people in the know on where to plumb them on forced induction 1275's?

I ask because with the new more serious and "valuable" engine going in soon I want to get it right.

Post by **Longdog** » Tue May 05, 2009 8:09 pm

I would have thought if it is a suck through set up the original way of venting into the carb would be fine.There should not be any foreign bodies in with the vapour.My s/c mog used this system as designed with no ill effects.

Post by **bmcecosse** » Tue May 05, 2009 9:42 pm

Bit of lubrication for the s/charger - won't do any harm.

Post by **Longdog** » Wed May 06, 2009 5:54 am

What's the spec of the new lump BTW?

Post by **superchargedfool** » Wed May 06, 2009 4:56 pm

big valve ported head. 1293cc with 18cc dished omega pistons. Fast road cam, 8.3:1 comp ratio. 10 psi on low boost, with 12 psi available but probably won't be used.

lightened and balanced everything. uprated oil pump.

Nothing too silly but just sorted.

It seems the serious way to go breather wise is to plumb the crank breather into the rocker box and then plumb the rocker box breather to a catch tank.

I think this is how I will go.

Post by **bmcecosse** » Wed May 06, 2009 5:01 pm

You should attach one of the breathers to the inlet - or you will have crankcase pressure and leaks all over the place. Especially with that overpressure on the s/charger!

Post by **superchargedfool** » Wed May 06, 2009 5:08 pm

it seems to be the way the serious mini boys do it.

Post by **Longdog** » Wed May 06, 2009 5:44 pm

Engine sounds like it will fly with that sort of boost.I take it that by fitting 18cc pistons you do away with the need for a decompression plate.

Post by **bmcecosse** » Wed May 06, 2009 5:56 pm

The Mini has additional breather on the transfer case! Mini doesn't have the rear oil seal problem our in-line engines suffer. It's your engine - if it were mine - it would be under negative crankcase pressure!!