Oil in inlet manifold

[TFN]

Good evening,

I'm getting a small build up of oil in the inlet manifold of my standard 1979 Sprint. It is usually after a run and the car has been left to stand for a few hours. It burns off at start-up (a rather embarrassing smoke screen) but doesn't cause any other issues.

The oil collects where the carb mount bolts onto the inlet manifold. I suspect it is coming from the crankcase breather. I don't think excessive blow-by gases are the cause as the engine was recently professionally rebuilt, although I will compression test just to be sure. The crankcase ventilation system looks in order, although I can't find a PCV value and there isn't any gauze where the take-off pipe mounts to the rocker cover - Does anyone know if there should be one or both?

So in summary - Has anyone else had a similar issue and if so what was the cause?

Thank you in advance

[xvivalve]

The gauze is only ever a flame trap.

On the Sprint, there us a steel plate on the underside of the rocker cover which acts as a baffle over the breather exit. These are usually simply held in place by the casting being peened or punched over their edges and can be found to be missing. If missing, it may allow excess oil to exit via this route and manifest itself where you are finding it.

You can see what crankcase pressure there is by removing the pipe from the rocker cover and seeing what pressure is generated there and how much oil is being passed out

[TFN]

Thank you for the reply xvivalve,

The steel plate is still there and securely fitted. I will 'Heath Robinson' an oil catch container next weekend and report back on pressure and volume of oil.

[xvivalve]

The flame trap should be located under that plate on a Sprint, I doubt it being missing would have much adverse effect....