I've been playing around with the tuning on Skender's Clubman GT today as well as chasing out an oil leak, putting in a set of electronic points and some other crazy but fun stuff.

When tuning the twin SUs, I block off the standard PCV, and do the usual balance, mixture and idle settings.
With the PCV blocked off, the idle is rock solid and all is well. When the PCV is unblocked, the idle becomes leaner (expected) but causes the idle to surge and become quite a lot rougher than usual, even at 1200 rpm.
I have the same set up on my own car with nearly identical engine specifications, the only difference is Skender has two crankcase breather instead of one.

Is some restriction needed in a PCV when there are two engine breathers fitted, or is there a method of checking a PCV I can perform to check if it is opening too much under manifold vacuum?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

sorry cant help you mick but im just chasing post counts..

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busier than a 0ne legged man in a butt kicking competion

There is a valve of sorts under the rubber diaphragm in the PCV. Check it seats properly. I can't recall if it fully closes when diaphragm pushed down. I have CRAFT disease...
If it looks wonky, you may need another PCV ....

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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.

We fiddled with the valve a lot today, I even inhaled something from a spare PCV when I tested the valve sealing by sucking and blowing through it

mmmmmmm.... mini PCV detritus....


I will switch skenders PCV out next time I get a chance to see if it's the problem, but thought there might be some other issue in the mix. Will the RE13 camshaft play a part in the problem? I am not really thinking it will as my own S has an RE13 as well with no problems.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

It won't be the RE13 cam, they only have about 274 degrees duration and .290" lobe lift.

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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.

Mick if the PCV is there of originallity and your not really fused if it works or not . . . fit a lovely shiny ball bearing to the hose between manifold and the valve, you will find it will run strong again

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http://www.youtube.com/watch?v=nDMkVq1jRGU

Would you believe we picked up a nice shiny former CV ball bearing today and had a close look at it to see if it would solve our problem......

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

And then where will it vent to, you have blocked all the flow!

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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.

Out the rear of the crank onto the clutch.

We're going to have another look at the problem tomorrow, it seems the PCV opens too much if you know what I mean. The mixture at cruise and idle goes very lean....I'm used to the PCV having an impact on the adjustment, but just not this much...
There's no appreciable blow by upsetting the issue, and everything else seems to be spot on...

I'll flip out the PCV with another and give it another shot..

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Try using a plain filler cap instead of the vented one. It worked fine on our 1275A+.

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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 had another play with it today Mick and did what we tried at your place, except I completely removed the PCV and blocked the hose from the manifold and put the breather hose into a bottle in the corner. It's now idling and running much better but still feels a little odd through the lower rev range while driving, just putt putt putting a bit. But when you put the foot down... WHOA! Away she goes!!

Gives us something to work with tomorrow - see you at 7:30 am.

Cheers,
Skender.

PS: It's worth mentioning at this point that mick makes THE meanest beef vindaloo. Sensational.

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Best part is that it comes back to visit later on....

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

especially when washed down with nice cold fizzy coke! It's the taste that keeps on keeping on!

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