Doc, given your comments about oil thrown at the Mechanical Fuel Pump hole (I believe the quote was "I had one hooked up on there, and over 4500rpm I looked like JB007" ), wouldn't that be the exception to the rule..? As in, if you're venting off the mechanical fuel pump hole (because you don't have a tappet chest breather, or one off the clutch housing), then you should have a catch can which feeds into the PCV ->air intake. Correct?

hahaha JB007 huh

i thought breather would go intothe catch tank then out of that into what you all call the PCV air intake..

wtf does PCV stand for.

Power Combustion Vrooom!!!!!!!

Yep, Doc says oil gushing out of the mechanical fuel pump hole into the PCV valve and then on into the carbs will cause you to pump lots of oil straight into your cylinders, resulting in a big oil cloud behind you. Creating a slick, just like JB007. Pretty well exactly what Doc wrote - even down to the term for everybody's favourite British spy.

PCV - Positive Crankcase Ventilation. As opposed to just hooking a pipe into the inlet. The Valve allows air out of the Crankcase when it is pushed out (put your hand over an open breather with the engine running - you might be surprised - I was when I did it the other day), but doesn't allow the engine to suck out more air than the crankcase wants to give. As the Doc (or was it Morris1100?) recently said in another thread, the PCV closes up (not completely) when the engine's sucking hard, so it doesn't suck oil or create a strong vacuum in the crankcase. It manages the crankcase breathing, as opposed to just hooking into an unmanaged/uncontrolled vacuum.

Hopefully I'm right there, Doc. Hopefully I'm learning!

Nic,,, maybe it`s best you com around here & have a chat about breathers,,, the good Doc is right & you really need to make sure your engine breathers are sorted properly because you coule end up with major oil leaks if you dont

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Another reason for having a pcv system as opposed to a system open to the atmosphere is that a hot engine expels air while the car is running.

Forgetting about possible oil leaks for the moment - when the engine cools it also sucks air back into the crank case. Given that its coming into winter, that cold air is also moist. So moisture settles in the crankcase.

So when you next start up the engine some moisture is being swirled around the oil system. That moisture does evaporate when the engine is hot but tends to form a creamy substance in the rocker cover top and rocker cover cap. To the inexperienced it looks very much like the signs of a blown head gasket.

A pcv valve will prevent much of the in/out flow of hot and cold moist air.

Mike

If you MUST make a breather off the fuel pump hole it needs a baffle, mounted so the oil thrown at it can drip back into the crankcase.
The MiniMania breather is made that way, if I needed to do this I would buy one.
It might be OK to run from there up to a catch tank, but as I said the PCV system sucked heaps of oil up there, I had to take it off. Could not see behind the car at 5000 rpm.

It is the last place I would run a breather from on a road car, I'd do one or more of the other 3 possibilities (flywheel housing, timing cover, butchered rocker cover) first.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I've got a 'butchered' rocker cover (I didn't do it, it's a chrome one that's been butchered before being chromed, 3/4" outlet), but Mad Mr Read told me when I was there last (which is a while ago, purely because it's a bit of a drive, and not a direction I regularly travel - like Padstow and Narellan for Doc) that I needed extra breathing. I've got an 1100S block - Matt said that there's not enough breathing up the pushrod holes, which makes sense, given they're only meant to be big enough to fit a pushrod. So there should be crankcase ventilation from the crankcase, not just above the head. He gave me the impression that the Rocker Cover is the least effective breather location - I could've misread that, but that's how I understood what he was saying. One he'd use, but only in conjunction with other breathers. And given my clutch housing hasn't been set up for breathing (it's not drilled), the simplest solution (no engine - or at least clutch cover - out of car) is to breathe off the fuel pump hole...

Which is why I've gotten around to thinking about it, and thinking that perhaps the easiest option is a breather off the fuel pump, into a catch can, PCV, inlet... Given it's a roady, it doesn't spend much time at 4500rpm, so it's not like the catch can won't have a chance to drain oil back into the engine block down the breather hose - provided the hoses are big enough (I think Morris 1100 said elsewhere that CAMS rules state they have to be 1" hoses for that reason - draining as well as breathing?). Also plumbing the rocker breathing into the catch can. And provided the catch can is well designed, with the ability to drain oil back, and hopefully also a sludge/water drain. Sound ok..?

So, I'm only thinking it's a work-around addition to the system for an imperfect breathing setup... A properly setup system - with a breather off the clutch cover (or timing cover) - won't need it.

Matt is right when he says there is not enough breathing from the crankcase to rocker cover area on 1100S style blocks.
Timing cover vent would be pretty easy IMO, bung a hole in one and attach a late 998 Clubby breather.

After my fuel pump breather problem I cut the flywheel housing breather hole in the car, with a 7/8" holesaw filled with grease. Yeah I caught most of the swarf, it was all gone 2 oilchanges later. Didn't appear to hurt the oil pump or anything else, alloy shavings are soft.
But I'll not do it again...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

With the Mech fuel pump...could you just modify and old crappy pump by drilling a hole into it and using it as a breather. I'v never actualy seen a Mech Pump

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Stop Licking the Dog...I Don't Care Who Started It

I made a catch tank out of PVC pipe, and have the flywheel housing breather going into there, and the PCV into the rocker cover breather.

I want a catch tank off the flywheel housing breather because it throws oil out of there when I do big left handers in motorkhanas, and when that goes into the PCV I leave a smokescreen...

I don't like how the PCV system requires a vented oil filler cap, it sucks in gunk

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did I tell you that I won a trophy?

but I have an electric fuel pump.

so what then.

That is why it has a filter in it. The filter needs cleaning at regular intervals.

Most people do! It's not located where the mechanical pump is, though. The mechanical pump's off the back of the block, your electric pump could be anywhere from next to the tank to under the bonnet. If there's no electric pump there, then you either throw a blanking plate onto the fuel pump hole, or, if you've no other breathing, you throw on a breather. No big deal having a blanking plate on there.

What's your current breathing setup..? Where are your current breathers..? That's what you're going to hook up to a PCV system and maybe a bling catch can.

Oh, and apparently the big Milo tins are exactly 2L. Perfect for making cheap catch cans.

I ran a sealed cap on the 1293A+, no problemo.
It never even tossed oil out past the ill-fitting A series dipstick either.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Can somebody please fix the spelling of the word 'catch' on this thread title?
It's driving me nuts!