Date: Wed, 8 Apr 2020 09:36:58 -0400
Reply-To: Geoffrey Toye <geoffreytoye@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Geoffrey Toye <geoffreytoye@GMAIL.COM>
Subject: 81 Vanagon Type 4 Motor Timing
Content-Type: text/plain; charset="UTF-8"
As a followup to this discussion, I swapped out the points and
condenser for a new Bosch set. Put the points gap at 18 thou which gave me
a dwell of 46 deg. This moved the dizzy away from the cold start valve to
give me room for future adjustments as the points rubbing block wears. All
good news.
The points I removed were pitted but probably serviceable if filed but the
rubbing block was notably worn compared to the new set. I lubed the cam and
centre felt. If I do this once a year I probably will never have this
problem again, unless I take out the dizzy drive gear and rotate it a tooth.
I set the timing at 7.5 deg BTDC to see what it would give me at 3000 RPM.
The advance introduced by the SVDA dizzy was way ahead of the target 35 deg
so I backed it off to give me 35 deg BTDC at 3000 RPM. This resulted in 4
deg ATDC at idle. Originally it was 6 deg ATDC so pretty close to being
back where I started timing wise which is good since the bus ran well at
that setting.
So now two more thoughts come to mind. Would installing an EGR valve as
originally designed and putting the timing to 7.5 deg BTDC give me any
performance improvement? Also, how do you take the distributor drive shaft
out? The Bently does it with a special tool, Tom Wilsons book pushes it
out with the cases split, the Haynes manual says use a tapered dowl pin but
leaves it there.
Any thoughts are welcome.
Geoffrey Toye <geoffreytoye@gmail.com>
Mon, Mar 23, 5:47 PM
to Vanagon
I bought an air-cooled vanagon last year and decided to take a look at the
points/dwell/timing situation while it was laid up for the winter. The
points are pitted (bad) and the dwell is 60 deg (hard on the coil). I
found the timing mark on the fan pulley by using Ratwell's information and
the sticker inside the engine compartment says the static/idle timing
should be 7.5 Deg BTDC.
On checking the static/idle timing I found it to be 6 Deg ATDC and that it
advances to 34 Deg BTDC at 3,000 RPM. The van starts and runs great. No
issues with power.
I would like to replace the points and advance the timing. The problem is
that I cannot advance the timing because the vacuum can on the SVDA
distributor is up tight against the cold start valve and I need to turn the
distributor in that direction. (I can find no markings on the distributor
to determine it's heritage).
Looking at other Type 4 engine layouts I see the vacuum can is near the
shaft that connects the air flaps and not near the cold start valve.
I have consulted the Bently and Haynes manuals and awaiting Tom Wilson's
book for more research. I have looked through the Vanagon threads and The
Samba discussion too.
I know the engine was rebuilt 25,000 kms ago. The PO was not an engine guy
so don't think he ever did the timing. Looking at the service records I
see it was done by others.
So two questions. Why does the van run so well with the timing so far
off? Is the incorrect positioning of the distributor due to the drive gear
being mis-oriented during the rebuild? Or am I missing something obvious
here.
Thanks in advance for any thoughts people might have on this issue.
Dennis Haynes
Mon, Mar 23, 6:52 PM
to me, vanagon@GERRY.VANAGON.COM
It is most likely the distributor drive gear is off by at tooth limiting
the adjustment. However, the timing is directly affected by point gap,
dwell. It is normal for the rubbing block on the pointe to wear which
reduces the gap, increases the dwell and retards the timing. So, replace
the points and condenser set, set the gap and the timing will be more
advanced.
As for timing, since most likely you are missing the EGR system you want to
run retarded as compared to stock settings. Waterboxers run ~35 BTDC at
3,000 rpm so I usually put the air-cooled engines without EGR there also.
The death kneel of these engines is unheard pre-ignition and thermal run
away of the heads and pistons. They can go from perfectly running to a
melted mess in a few minutes.
Dennis
Geoffrey Toye <geoffreytoye@gmail.com>
Mon, Mar 23, 7:00 PM
to Dennis
Thanks Dennis. Great insight.
Yes, the EGR system is missing.
Since the van has been running for 25,000 Kim’s I assume all is well, it’s
just not right?
Will put in new points/condenser and see where that puts me.
Thanks again.
