[Healeys] BN1 PCV system

Harold Manifold manifold at telus.net
Sat Jan 30 16:48:32 MST 2021


I am also looking into a PCV system for my BT7 as well. Most of the PCV
systems I have seen on Healey's don't have a filtered fresh air intake and
don't have much ability to replace the blow by and other nasty's that will
accumulate in the bottom of the block. To have air changes in the bottom of
the block a filtered fresh air source is needed and slight vacuum to draw
out anything that accumulates. Ideally the fresh air would come in at one of
the block and the bad air leave at the other end. There is a connection
between the tappet section and the bottom of the block but this is also the
oil return. (A BN1 engine may be different) A PCV can be used to control the
system but if the air circulating bypasses most of the engine then the
system is less effective. On V8 engines the clean air comes in through one
valve cover, passes through the bottom of the block and then exists via the
other valve cover drawn by vacuum from the intake.

Any good ideas where to locate a filter fresh air source?

This website has excellent information on PCV valves and is where I found
the attached article by Tony Ball.

http://mewagner.com/

Harold



-----Original Message-----
From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Bob
Spidell
Sent: Saturday, January 30, 2021 2:41 PM
To: healeys at autox.team.net
Subject: Re: [Healeys] BN1 PCV system

Looks clean, Michael. I am considering similar for my BN2 (but I plan to fab
a plate with an elbow to replace the road draft tube). If you plug the valve
cover vent, you'll have a 'system' similar to what I have on my BJ8, which
is an updated version of the original Norman Nock design. 
This isn't really a PCV system, as the crankcase and valve cover will be
under continuous vacuum. I suspect some air is drawn in from the rear
'seal,' which is not filtered but helps to alleviate the infamous Healey
bellhousing drip, and likely doesn't affect mixture all that much. If you
leave the vent open--I'd put an air filter on it--you'll have a genuine PCV
system as air will be constantly circulated through the crankcase and top
end. This is what I plan to do, but my 100M is vented to the CAB, for which
I have a large K&N filter on the intake duct in front of the radiator.

Which PCV valve did you select?

Bob



On 1/30/2021 12:20 PM, Michael Salter wrote:
> After months of deliberation I have constructed this PCV system for my 
> BN1.
> The original road draft tube has been plugged just below the PCV valve 
> takeoff.
> Of importance was that the system would be almost impossible to see 
> without very close inspection.
> I'm still trying to decide if I should plug the normal valve cover 
> vent or leave it open to serve as the PCV system intake.
> Thoughts?
>
> M
>

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