Bob will correct me if I'm wrong, but I think he's saying that as he has
no PCV, and therefore no "assistance" in removing the crankcase pressure
(courtesy of the vacuum in the intake manifold), the way to relieve the
pressure is to have as many outlets as is feasibly possible.
What I don't understand is why there is still a need for the calibrated
hole in the filler cap. Surely any calibration there is redundant in
light of the fact that you now have a couple of gaping holes elsewhere?
My car is a '66 with the PCV valve. My engine leaks nothing, so I will
agree that the system appears to be effective in reducing crankcase
pressure. The only problem I have is that it tends to suck oil out of
the engine (not much, but there's always a nice pool in the bottom of
the valve). I think part of the reason for that is that the connection
to the crankcase in the 1098 engine is via one of the tappet covers on
the side of the engine, which I've read (on an MGB BBS) is not the ideal
place for such a thing - too much oil sloshing around in there!
Phil
|-----Original Message-----
|From: Guy Weller [mailto:guy@weller-lakes.freeserve.co.uk]
|Sent: Friday, May 10, 2002 2:28 AM
|To: Robert E. Shlafer
|Cc: spridgets@autox.team.net
|Subject: Re: Rear Main Seals
|
|
|Cap'n,
|That is an interesting and comprehensive description of your (car's)
|pcv system.
|
|Just wondering why it is necessary to extract from the fuel-pump
|monting plate position as well as the timing gear cover? Don't they
|both in effect draw pressure from the same space - i.e. the crankcase?
|What's the advantage of the dual system?
|
|Guy
|PS - serious this time Bob, - honest - no catches here!!
|
|
|----- Original Message -----
|From: "Robert E. Shlafer" <PilotRob@webtv.net>
|To: "Phil Profili" <Phil.Profili@cptii.com>
|Cc: <BlkBT7@aol.com>; <spridgets@autox.team.net>
|Sent: 10 May 2002 03:14
|Subject: RE: Rear Main Seals
|
|
|> As far as an engine PCV set-up, yes.
|>
|> It is designed to run with an otherwise
|> closed crankcase with the possible
|> exception of a small hole in the filtered
|> oil filler cap, as specified (or not) for the
|> original application.
|>
|> The above having been said, the otherwise "vented" (through
|breathers -
|> no PCV system)
|> crankcase is a purely "open" system.
|>
|> My new Rivergate engine is "open
|> crankcase". It has no PCV system.
|> It has a 1/2" breather on the valve
|> cover and another 3/4" breather fabricated
|> over the hole used by the old mechanical
|> fuel pump. It has the Rivergate rear engine plate incorporating a
|real
|> oil seal.
|>
|> It is a tuned 1293 "tailored" for low pressure supercharging
|(Judson)
|> running
|> a static CR of 8.3-1 (aluminum head).
|> The engine has just done 500 miles and
|> is now being pushed to 4,500rpm every
|> now and then....it still has a tendency
|> to run on the warm side (not fully broken
|> in as yet) but, absolutely no oil leaks thus
|> far; absolutely none.
|>
|> The oil filler cap also has a small,
|> calibrated orifice.
|>
|> All "holes" for beathing are filtered, including the calibrated hole
|in
|> the oil
|> filler cap.
|>
|> The PCV set-up (a la '67 timing case
|> cover to intake manifold through diaphragm equipped "valve") works
|> best. The carbs are out of the PCV
|> "loop" (unlike later emissions applications)
|> and are thus, spared contamination by
|> crankcase gasses. The crankcase
|> vapors are literally "sucked" out of the
|> crankcase through "calibrated orifices"
|> into the intake manifold to be equally
|> distributed to all cylinders in proportions
|> that are cleanly combustible. Crankase
|> pressure (against oil seals) is minimized
|> accordingly.
|>
|> This particular "early" PCV set-up is
|> a "friend" of the engine, unlike later
|> set-ups which contaminated the carbs.
|> with all sorts of crankcase vapor "junk",
|> eventually "gumming up" their works. Of
|> course, the priority at this point was
|> cleaner air through more complete
|> combustion, not performance or even
|> economy.
|
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