Well, now *I* am confused.
Both my TR-4A and GT6+ have (had) the old style Smiths PCV valves -
large, with a rubber diaphragm and spring. The TR's was just flopping
around atop the manifolds, because the mounting bracket was missing. I
bought a "modern" PCV valve to replace it - a generic one for a
four-cylinder car (a Volvo, I think) and cobbled up some hoses to
compensate for the fact that the original has 1/2" fittings everywhere
and modern ones have 1/2 on one end and 3/8 on the other (presumably so
Joe Mechanic can't install them backwards).
My take was to install the valve so that the airflow was from the block
to the manifold - this ends up having the 1/2 end at the valve cover
and the 3/8 end at the manifold. I determined this direction by
sucking/blowing on the PCV valve and noticing which direction allowed
air flow - one allows a lot, one allows a little.
Now I'm wondering. Dennis' description of wanting to (mostly) block off
the crankcase at (idle) high vacuum and allow lots of flow at (open
throttle) low vacuum makes me wonder if I've had the valve in backwards
all this time. I'm about to redo the plumbing, so now would be the time
- I've never noticed a particularly rough idle, but it's been a long
time since I've heard it with the original valve (I still have it, I
guess I could hook it up and see).
Comments?
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