37 replies to this topic

[Yoda]

Just make or buy a catch tank. An old radiator expansion tank would do You could fit a filter to the outlet for good measure. or run a pipe to the drivers side of the cabin and suck the pipe like someone already said

That last part was a joke by the way DONT do it.

[Spud_133]

want to see what happens when your piston rings are excessively worn and so pressurises the crankcase, which in turn 'breathes' out of the breather, have a watch of this video, it's my stock car engine which we just took out
http://i902.photobuc...os/89121922.mp4


Ps, keep your twins. John Cooper wouldnt have fitted them for no reason....!

[Yoda]

Ps, keep your twins. John Cooper wouldnt have fitted them for no reason....!

I was going to say exactly that. They were fitted for a reason, and i like that reason. My old Mk1 cooper had them and the low end power was superb. add an RC40 exhaust and a tune up and your good to go. You WILL notice a difference.

[thebullet]

Has a single box centre exhaust, Colin at southam minis reckons we can best the 58bhp it got on the rollers last time. Think I may think about a catch tank! Cheers guys!

[Ethel]

The carb connection you get on single SU's is upstream of the throttle disc, which isolates the vent pipe from full manifold vacuum. The valve in the first piccy has a diaphragm to atmospheric pressure so it sucks itself shut is the vacuum gets too much.

[Yoda]

Duly noted Ethel.

[bmcecosse]

Early cars may have had 'twins' because that was the rage and it was considered 'sporty' - but they soon came to their senses and fitted a single large carb. Vizard explains it - each cylinder sucks in air individually, and there is no 'cross flow' in the horrible BMC twin manifold - so each cylinder can only suck through ONE small HS2 carb with tiny twins fitted. But can suck through the larger HS4 carb with a large single - but to get the best of it, you need a good flowing manifold without a heat spot. The beauty of the SU carb is the variable choke size due to the rising piston - so there is still good high speed flow across the jet bridge even at low revs. All this talk of 'better torque' etc with tiny twins is nonsense - I've used/tried them all. It's all down to proper set-up. And a catch tank system will not draw the fumes away - do the job properly with a suction system if you don't want leaks - and don't want to be breathing in oily fumes.......

Edited by bmcecosse, 27 May 2012 - 02:38 PM.

[jaydee]

You need this but looks like out of stock..
http://www.minispare...id=35134&title=

Buy two of these:
http://www.minispare...id=34394&title=
and fit them between manifold and heatshield
run a section of pipe from them to a Y piece like this:
http://www.minispare...id=33168&title=
and connect the breather to the Y piece, jo done.

Do not run the breather to filters, if you dont want them connected to the carbs (IE:the later twins has a connection to carb and not the manifolds, giving balance issues so some decide to not run breathers to the carbs) then run them to a catch tank..

[The Otter]

You need this but looks like out of stock..
http://www.minispare...id=35134&title=

Minispares messed me around a little on this, as it was only me trying to order the valve that let them know it was out of stock, so I had a quick search on eBay and found one cheaper and in stock. It's advertised as an MGB valve but it's exactly the same part number and is working fine on my car, so if you do go down the route of the PCV valve then you can get one of these:

http://www.ebay.co.u...1#ht_500wt_1180

[Tinkerbelle]

Just to add my 2ps worth. I had twin HS2s with breather inlets. I was told not to vent to these due to power but many smelly trips and a dusting of oil over the clean block every 100 miles or so led me to connecting the breather up without any loss in power.

I subsequently went up in the world and got a pair of twin HS4s without the breather connections, all I did was drill a hole and gromit in a pipe leading from a x piece and onto each breather into the cone filter housing, so low vacuum side of butterfly and does not make filters oily.

Photos to follow if required. All clean and runs fine.

ALWAYS TWINS, don't let the non-believers talk you out of it.

Matt

[thebullet]

Mini and metro centre adviced me to run it open and down the side of the radiator to the floor, well I guess that is easy. They say they do it to all their cars with the same issue, says it runs better too.

[thebullet]

You need this but looks like out of stock..
http://www.minispare...id=35134&title=

Buy two of these:
http://www.minispare...id=34394&title=
and fit them between manifold and heatshield
run a section of pipe from them to a Y piece like this:
http://www.minispare...id=33168&title=
and connect the breather to the Y piece, jo done.

Do not run the breather to filters, if you dont want them connected to the carbs (IE:the later twins has a connection to carb and not the manifolds, giving balance issues so some decide to not run breathers to the carbs) then run them to a catch tank..

That is interesting, seems an easy way to do it actually.

[liirge]

Mini and metro centre adviced me to run it open and down the side of the radiator to the floor, well I guess that is easy. They say they do it to all their cars with the same issue, says it runs better too.

******* ocks!
I've commented on this too many times on here. If you do do this set up don't EVER go onto a track.

Edited by liirge, 29 May 2012 - 05:06 PM.

[jpw1275]

Im currently refurbing a set of twin hs2's and hopefully sticking them on.... As for the breathers.... Am i right in thinking having a tube from each breather to a y piece then into my manifold ? At the mo my manifold has a one way valve on so i guess it goes to that so the gases dont back track? And sorry for the high jack

Cheers james

[jaydee]

Yes, connect breathers via Y piece to the valve on the manifold.