Date: Wed, 31 Mar 2010 23:59:57 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Timing/Distributer question
In-Reply-To: <011b01cad12d$e44ff7e0$acefe7a0$@net>
Content-Type: text/plain; charset="US-ASCII"
That port is for the vacuum "retard" chamber. It gets connected to full
manifold vacuum. There is a port near the throttle but sometimes this does
not work if the throttle bushings are worn. Tee it with the vacuum line on
the fuel pressure regulator.
This port has some real specific and important functions.
For starters this port is needed to fully retard the timing at idle. Without
it working, setting the timing near spec will cause insufficient advance
when needed.
Vacuum retard is used to reduce advance during part load operation. The goal
is to reduce peak flame temps to reduce NOx emissions, pre-ignition and
melted pistons.
When properly set up and working, the timing will advance very quickly as
soon as the throttle is opened, even slightly. The port on the other side of
the vacuum chamber goes to the port on the throttle body above the throttle
plate. That will add to the advance as the throttle opens.
It may seem like a good idea to advance the timing past specifications. No
problem for a few degrees but 10 BTD can be dangerous. First will be the
increased production OF NOx for the Catalyst to deal with. This can also be
a problem for dyno emissions tests. Next, while this does improve throttle
response and make the engine feel more powerful, it does not help much at
full throttle and will increase the chance of pre-ignition. On the water
boxer you do not always hear the "Ping" when it happens. Especially at speed
with the AC on. You may be OK for years but at some point on that long trip
going up that hill with the pedal mashed here comes those melted pistons.
One of the reasons this engine is de-tuned is so that it can be pushed when
needed.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of B
Feddish
Sent: Wednesday, March 31, 2010 7:57 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Timing/Distributer question
Way back when I was having my "running like crap" saga with my old engine I
had taken it to one shop that found some ground issues but they also set my
timing , etc. to factory specs. The van was unbearably sluggish when I got
it back. Finally, after lots of items with my last mechanic he finally
pulled the vacuum line to the front of the distributer, stuck and screw in
the hose to block it then set the timing 10 degrees advanced. The van ran
like it had Zetec in it. (OK, an exaggeration.) It ran fantastic, plenty of
power and gas mileage was ridiculously high, 18-19 city and 23 highway in an
'83 Westy.
OK, I get my van back from the guy who put the new engine in. He tells me
that my mechanic had the wrong hose in the rear vacuum connector of the
distributor but I did notice the other hose still laying there with a screw
in it. I'm sure the mechanic set the timing to spec. Anyway, the van has
smooth power throughout the entire band but is really sluggish. Nowhere near
the power of my low compression leaky old motor. Here is a picture of my
current distributer:
http://www.feddishbasses.com/vw/dist.html
I'd like to get this engine running with a little more power. What is the
opinion of the list? Should I re-connect the vacuum hose? Can I advance
the timing safely to get more power? If so, how much is safe without harming
the engine?
Thanks,
Bryan