Hi all,
I hate to bring up this subject again but, during a conversation with another
Healey owner, a couple of points came up that have not been mentioned during
our extensive discussions. Since the choice of PCV seems to have been made on
little available information (As I understand, selection was made on a rough
displacement match for a carbureted 6-cylinder), it is with luck that the unit
picked has a specification profile close to the one required to satisfy the
unique characteristics of the Healey engine. If the selected valve evacuates
a less-than-required blow-by volume, a crankcase pressure buildup will occur
greater than the original system. If the PCV is too large, it will suck an
excessive volume of oil and oil-vapor into the intake manifold and diminished
combustion efficiency. Additionally, on a BJ8 with a vacuum assist brake
servo, it was brought up that, since the PCV vacuum tap would be close or
share the same manifold port, when the engine is turned off, oil-vapor under
pressure in the crankcase, would penetrate the intake manifold and eventually
find its way to destroy the rubber parts of the servo.
I had been seriously considering the installation of a PCV in my 64BJ8P1 and
was considering the installation of an oil catch can between the crankcase and
the PCV valve to trap oil and oil vapor from heavily contaminating the valve
or entering the intake manifold. During a simple vacuum test (without the oil
catch can) of 1968 Mustang 200CI PCV, I found that vapor continues to be
expelled from the valve when the engine is off. I am not sure that an oil
catch can will stop brake servo contamination but I decided that I would
rather clean my garage floor than risk that condition.
Thoughts?
All the best,
Ray 64BJ8P1
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