[T3] On a 73 T-3 SB fuel injected auto trans pinging

Bobsnotch at aol.com Bobsnotch at aol.com
Sat Dec 9 17:58:18 PST 2017

In a message dated 12/9/2017 8:30:58 P.M. Eastern Standard Time,  
phil.hof at ostronic.org writes:

Lastly,  I’ve said this before, but the late model breather/PVC is 
different than the  early style, and I hear that faults can cause vacuum leaks that 
might cause at  least some of your symptoms.  If anyone has a good diagram 
and discussion  of how the late PVC system works, we could set this right and 
eliminate  another variable.
This is the 1 thing that Ray really doesn't like about the 2 cap PCV system 
 VW used. It has a bad tendency to open when it wants, and causes a miss. 
What  most of the type 4 guys do, is to strip out the guts of the valve, and 
add a  slug with a drilled hole in it (can't remember what size right off 
hand) in the  vac hose to the plenum. What this does is allow you to tune 
around the "constant  vacuum leak" of the small hole. I only mention this, as 
all of the type 4  engines (bus, T-4, 914) use that same valve set up, and 
have issues with it. I  haven't really studied how the VW designed PCV system 
really works, but then  I've only got 1 t-4 engine here, and it's on carbs. 
The rest of the type 3  engines are all 1 cap breather models, so no real PCV 
set up.
I hope this helps.  

Bob 65 Notch  w/Factory Sunroof converted to IRS
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