Date: Thu, 12 Dec 1996 17:04:05 -0800 (PST)
From: Mike West <mwest@cdsnet.net>
Subject: Crankcase ventilation & Blow-by

 "I've been tricked!" he cried.

 They really should have said something in the manual.

 While I was out in the South China Seas fighting for God, Country
and The American Stock Exchange, the Krafty Krauts were home plotting
to make me look bad in the '90s.


 Well, I put a sand seal on this case I'm working, for the reasons
most of us know about.

 It pulls in air and dirt with it. That sounds dumb eh?

 In other cases it blows oil from too much blow-by.

 Then, I was doing some reading on the smog stuff since we need to
know that, and stumbled on the reason it was sucking air.

 Another "clue", is there is a type3 head out there that has an air
inlet tube built right into the rocker arm cavity.

 What's going on here? No manufactuer will even drill a hole if he
can help it.  (heavy sigh, look of bewilderment)
  
 Positive Crankcase Ventilation (PCV) isn't just there for Tree-
huggers.

 It pulls off nasty fumes etc and blow-by and sucks them
up into the carby and burns them.

 You want to get that moisture out of there, right? How?

 My engine likes this. Keeps some of the "nasties" from becoming 
acids in the oil for instance. Cuts down on varnish and sludge 
build up. Eliminates gas fumes.

 There's even a percentage of oil that "bonds" to oxygen while being 
whipped around in there and those are no good now either.

 "Oxidation"!  Same as rust only different.

 I want them out of there!

 The way all this PCV works is there's a partial vacuum or "negative 
pressure" created by the hose that runs from the air-cleaner to the 
Oil fill tube.

 It gets positive pressure from the blow-by and any more air it needs
it pulls in thru that pulley shaft.

 Voila! we have thru-ventilation!  Rauf die ne naza! as my wife used
to say. 

 So one, I have to run that hose to my air-cleaner, and two, I imagine
I'll put an inlet on the rocker covers with an air cleaner on it.

 Or I could tap a hole into the top of the casting like the type3 job
I spoke of and leave the covers alone.
 Of course then I'll probably have to modify sheet metal :-(

 Three, you need that rubber boot that goes on the "road tube"
off the oil fill tube. The one that runs down to the road.

 If that rubber boot isn't on there or in bad condition, it
breaks the vacuum you had going for you. 

 I just cured some of you guys "blow-by problems, hey?  :-)

 The story wouldn't be complete if I didn't talk about the non-
existent "PCV valve" we never had.

 It's just a check valve with a light spring in it. Sets in the 
vacuum side of this system.

 The big iron 8's at least, draw so much vacuum at idle, that the
PCV setup can draw so much fumes it affects the idle mixture.

 The PCV valve takes care of that. It pulls against the spring and 
closes down partway. Some others just have an orfice restriction.

 So this child will go find one, on the off chance it might be needed.

 It is possible that the little rubber booty we spoke of handles this.

 I wouldn't put it past them. 

 This may be of some impact on you California guys passing Smog.

 Just slip it in the line that goes to the air cleaner up underneath
where it can't be seen.

 Now if I can get that fool in front of me on the freeway to stop
blowing his pollutants into the path of my engines air supply.

 His crap is being sucked right into my engine!
  The man has no conscience! Arrest that man!

 Never mind the guy behind me, that's his problem.  :-) 

 west