Crankcase breather - advice needed

[hyperhale]

Hi All

I'm a new member to the CT club having purchased my first classic, a 1972 Spitfire mk4.

The spit has had K&N pancake air filters fitted to the twin SU's in place of the original air filter box and I assume the inlet manifold has been changed from stock as the crankcase vent pipe now runs down the side of the engine with a small filter on the end.

I assume this has been done as there is no where to connect the pipe on the manifold.

Problem is that my better half is complaining about the faint smell of oil vapour in the car.

I would appreciate any advice regarding other options,  ideally I would like to vent back into the manifold but understand that the positioning is important with the pipes originally connecting very close to the carbs.

Also interested to know what the benefit is of not venting to the manifold as this appears to have been changed intentionally I assume for some sort of performance benefit.

[HMaze]

Hi hyberhale,
it has probably been changed, because the PO put some early HS2 (up to Mk3) on a MkIV inlet manifold.

Mk3 used a PCV valve on the inlet manifold (blanking plug on the right), while the MKIV used two connections on the carbs themselves.

Harry

[hyperhale]

Now confused as found a drawing in the original mk4 handbook and what I have is completely original....

So therefore where should the crankcase breather pipe connect to?

[HMaze]

Those are not original MKIV HS2 carbs!

Harry

[yorkshire_spam]

You sure it's oil vapour and not fuel? Not sure about the MK IV,but my '78 1500 has a connection on the top of the fuel tank that needs blanking off... replacing the blanking got rid of 90% of the petrol fumes smell on my motor.

[hyperhale]

Thanks harry,

Yes I see what you mean now,  so if I wanted to find an alternative way to route the pipe could I obtain a pcv and tap into the manifold ( after removing it)

Pete

[hyperhale]

6797 wrote:

You sure it's oil vapour and not fuel? Not sure about the MK IV,but my '78 1500 has a connection on the top of the fuel tank that needs blanking off... replacing the blanking got rid of 90% of the petrol fumes smell on my motor.

Definitely oily smell rather than petrol

[thescrapman]

Fit a much longer pipe, preferably one that reaches the rear of the car.

Or obtain a mk3 manifold or mk4 carbs

[hyperhale]

Thanks for the advice fellas.

I have gone down the route of buying the pcv valve and removing the blanking plug on the manifold to install it that will basically give me a mk3 set up.

[nang]

Here's my Mk4. Breather hoses from carbs to rocker cover. (Sorry the pipe to the rocker cover is hidden by the throttle cable.)
Tony.

[That Man]

10041 wrote:

Thanks for the advice fellas.

I have gone down the route of buying the pcv valve and removing the blanking plug on the manifold to install it that will basically give me a mk3 set up.

I'm not sure there is a blanking plug, it's a while since I've looked at one of these but I'm pretty sure that hole has not bean drilled out whilst in production, so that would be a machine shop job after the manifold has been removed

Gordon

[Dannyb]

I believe your 100% right there Gordon