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Mark

Smoke From Rocker Breather

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Hi all

As previously mentioned Vitesse finally up and running after 13 years, just been running it locally to where I have a lock up, not venturing to far, bedding in brakes etc. Noticed when it's up to running temperature there is a slight puffing of smoke from the rocker breather. The engine has 62,000 miles one previous lady owner. I did strip the engine, checked the bores, big ends and mains, years ago and at the time all seemed good so just replaced the crankshaft thrust bearings. I bought an exchanged unleaded head from Canley's as I suspected the valve guides at the time of the first run around the block when I first bought the car. No smoke from the exhaust on take off or idle now.

At the moment the breather is open and I was going to plumb it into the SU's, but then thought I would run it to a catch tank. Just can't remember what is an acceptable amount of blow by,  if any, if this is what it is. Covered 29 miles so far although the engine has probably idled for a few hours since I got it started.

I did a compression test today, throttle open old Gunson Compression tester.

           1        2        3       4        5       6  

Dry    155  155   150   155    160   155

Wet   240  240   240   245    230   230

I should have measured the amount of oil I added to each cylinder, as wet it would hit over 280, if I added to much.

Think I may have a slight oil seepage from the head gasket close to where the engine number is stamped, but was going to get a few more miles on the engine before I re-toque the head. 

Tried videoing the puffing from the breather but doesn't show up .

whats your thoughts?

Mark

 

 

IMG_6829.jpg

IMG_7089.jpg

Edited by Mark
Additional Photo

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Hello Mark,

Nice to see the car at last,i run mine from the breather to a small catch tank which is then vented to the air through a small filter,5 years+ and there is a small visible amount of

oil in there.

 

I`d say yours needs an Italian tune up.

Steve

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Very nice, looks very original, so if that's your bag, send the vapour to the intake.

A catch tank does just that, and needs emptying after X miles, depending on emissions, which is a pain, as what comes out looks disgusting!    Take off the oil filler cap, for its larger diameter.   A slight breeze is normal, as yours sounds like from the vent tube.

JOhn

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Mark

Nice looking Vitesse.

I see you are running the later inlet manifold and a set of 1 3/4" SUs.

Vitesse/GT6 of this period would breath through a Smith PCV, which is intended to apply slight vacuum to the rocker box under all conditions and direct vapours to the inlet manifold.

I have retained this arrangement on my GT6 but have added a small catch tank which the PCV effectively 'breathes through'. It collects a bit of oily 'stuff' and allows the inlet to run a bit cleaner.

Might be of interest. PM me if you would like more detail. Photo attached.

Ian

DSC_3686.jpg

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Thanks for the replies.

Hi Ian, thanks for the pic.  I'll probably end up doing something similar. I have a Gt6 mk2 with the standard set up. Just at this point I was a little surprised about smoke puffing out of the breather,  and couldn't remember what was a normal amount. I would have expected it on a cold damp day,  but a bit wary on a warm sunny day.  I'll initially run a pipe into a catch can without recycling,  put some miles on it and check the results. 

Mark

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negative pressure is need in the crank case of any engine in any application.  It can be applied to the engine or a catch can connected to the engine.

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On 6/4/2019 at 1:27 AM, 122344 said:

negative pressure is need in the crank case of any engine in any application.  It can be applied to the engine or a catch can connected to the engine.

Hi,

Nice engines.

 Sound advice. Has potential to eliminate oil leaks.

My attempt of PCV is a fail. Do not connect to an unused mechanical fuel pump blanking plate unless you block flow while engine running.

Cheers,

Iain.

Cheers,

Iain.

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What happened, Iain?

I mount my catch tank high, with a large bore hose directly to that mechanical fuel pump hole in the block, so that oil vapour condenses in the hose and runs back into the sump.    Water vapour condenses at a lower temp and is vented from the tank.   The result is, no condensate in the tank!  None at all.   And no leaks.

You only need a PCV if you want to vent the fumes into the intake manifold, else the high vacuum at low throttle will draw an excessive amount into the manifold, ruining your mixtures.

John

 

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my set up almost identical to joyhn's and zero problems in competition, did make mistake once in the holy grail of finding mounting places in vitesse engine bay of having pipe with a drop to catch tank, lots of oil condensation occurred that then ran the wrong way and mixed with the water condensation stopping it get away and forming a nice emulsion quite quickly, we live and learn!

IMHO the last thing you want in the crankcase is negative pressure as the only way you will get that is sucking and at anything other than idle you don't want to be sucking whats flying around inside there. hopefully the crank breather pipes let the pressure trend toward neutral. never liked the later rocker cover feed to su carb set up designed to get carbs and inlet manifold mucky. the early frying pan pcv that sat between rocker and inlet manifold post carb on vitesse and gt6? was actually a very clever device opening and closing exactly when required. if i ran a standard roadgoing engine i would retain it in favour of any other option.

 

alan

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Hi John,

 I have connected the bottom of a catch/separator tank to the mechanical fuel pump hole in the block. Filtered atmosphere to the rocker box via hose joiner AKA PCV valve.

The final connection is between top of catch tank & inlet manifold. Via the manual adjustable ICV. 

I have to use the ICV inlet as its the only available connection to inlet manifold. idle RPM not too effected as I use dredded ignition advance to control idle.

Mk I gave great clouds of smoke on acceleration after arriving at the end of slip roads.

Added a long 1/2" ID hose to top of catch tank and a small filter. Mk II was born. No more visible smoke. 

 

Car in garage getting seals replaced to cure the front-end leak.  A complete rethink required for MkIII.

& that's why my invention is kak.

Cheers,

Iain.

 

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Hi all

Followed the same layout as Ian after running direct to the catch tank for a while. I'll monitor and check plugs after a while to make sure they're not fouling up. 

IMG_7252 (1).jpg

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Hi Mark

I was struggling to see where you had positioned the catch tan, then spotted the little blighter hiding behind the suspension turret. Looks like the same unit as mine.

The can itself is actually quite nicely made but needed some internals. I also had a leak initially where the base screws into the body. It had been sealed with what appeared to be scrapings from a wok, now resealed with Hylomar and holding fine!

Ian

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I found that at high rpm (7000ish) I was getting a lot of smoke from the cam breather. So I un-blanked the block breather and fitted a simple take-off. That could fill a catch tank in 15minutes.

Next idea, I didn't have space for the large oem takeoff ( clever internal baffles etc) but I made a simple baffle to help reduce oil surge up the breather, and then a bit of 1" steel tube about15" long that is almost vertical to get as much oil as possible to drain back.

That sorted most of the issues.

It has been further refined. The block and cam breather are now T'eed and onto a 1/2l catchtank, which is in turn connected to the airbox to provide a bit of vacuum especially at high rpm. This has cured the oily smell on the few journeys I have tried, but yet to be used in (serious) anger. 

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1 hour ago, zetecspit said:

which is in turn connected to the airbox to provide a bit of vacuum especially at high rpm

if you have ANY vacuum in the airbox even at high rpms then you have a problem(think about it), air passing through that might pick up and carry any vapour managing to find its way along the pipe from the catch tank maybe, where a bit of pressure from cam or block would encourage the vapour to head down the pipe

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I think it is useful? At high rpm any vapour that is sucked in will be so diluted by the airflow it shouldn't make any difference?  I thought all modern cars used pcv valves, so even at high rpm there is still some vacuum pulling the fumes?

Or have I misunderstood?

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Hi,

 You do not want less than atmospheric pressure in your "plenum". I hope when i'm driving along its positive.

You want the highest pressure differential possible.

Cheers,

Iain.

Edit. Inlet absolute pressure will always be lower than atmospheric, So will always want to pull from somewhere.

Cheers,

Iain.

 

Edited by spitfire6
Edit

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My airbox setup should keep pressure reduction low. The filter is rated at about 400hp, so plenty. Plus 100mm tube to the airbox.

But I am always sceptical about ramair effects and filters. Guess Iain has/could pop a map sensor in the airbox to check? Need one outside to compare?

Anyway, the airbox being fed the cruddy stuff makes the car nicer....but proper testing still needs carrying out:whistling:(7000+rpm)

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Hi,

 my air filter is about 100 Cm's from the inlet plenum. Only way I could guarantee "cold" air at low car velocity.

I doubt at WOT I have a positive DP. Like to imagine I do!

Cheers,

Iain.

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