Capacitive discharge ignitions--info requested
Doug Calvin
standard VW ignition system to a capacitive discharge system? I'd also
like to learn about related topics such as spark plug wire requirements
for such systems, etc. (Just read the discussion re. platinum plugs,
thanks everyone) Such help would be much appreciated.
Doug Calvin
Veeduber
>standard VW ignition system to a capacitive discharge system? I'd also
>like to learn about related topics such as spark plug wire requirements
>for such systems, etc.
Doug (and the Newsgroup),
Call Universal Corporation in Grand Junction, Colorado (970) 242-5267. Order
their points-triggered CDI unit. Cost is about ninety bucks.
Screw it on. Wire it up. Should take you about thirty minutes. If you need
help, ask.
Make sure it runs. (I've had one bad unit out of the box in about 200
installs). Pay attention to the details. Provide a good ground and air-flow;
the case is the heat-sink for the transistors in the inverter and the SCR in
the triggering circuit.
Works okay? Good.
Now it's going to eat your stock plug wires. That's because your coil is now
putting out its maximum voltage at ALL engine speeds. Before, it could only
put out max spark voltage below 2500rpm, dropping off steadily above that
point. The consistantly higher voltage will cause neoprene-type insulation to
break down rather rapidly. You need lead with better insulation, such as
silicone.
So replace the wires. Get a set of non-metallic silicone-insulated VW-specific
spark plug leads from J.C.Whitney. Cost you about $10 and should last at least
eight years. (I've had a set on my baja... out in the weather... for more than
12 years.) This set of ignition leads comes with the Corvair-style air-seals
-- the kind that really work. Only bad point of these wires (also sold in
blister packs at much higher prices by several other suppliers) is that the
air-seals are natural rubber -- they'll go bad in about three years. So dose
them up good with Armor-all and keep them clean. If you got the bread, order
TWO sets of wires, store the spares in the crisper of your refrigerator. (Away
from ozone and UV, stored below 45 degrees Fahrenheit, rubber don't go bad.)
Plug in your new plug wires. Do it one wire at a time. The coil lead will be
about a mile too long so shorten it. Use a pair of regular pliers, a pair of
needle-nose pliers, a razor blade and a small screwdriver (no, smaller than
that...), un-crimp the crimped-on connector from one end of the lead. Shorten
the lead as required, being sure to observe the manner in which the graphite
center conductor is folded over- then crimped under... the connector. (Cut the
lead about an inch longer than you need. At the required length, cut down
through the silicone insulation with the razor but DON't cut the graphite --
don't worry, the stuff is tougher than it looks. Be careful not to cut
yourself. Now just strip off that last inch of insulation and leave yourself
with a 1" pig-tail of the center conductor.) Now put the connector back on the
wire with the center conductor properly trapped under it and use your regular
pliers to re-crimp the connector. (don't forget the spray-cap... the little
black bootie-thingee...) All done? Then trim off any excess center conductor
-- you only need enough to make good contact with the connector.
Now fire it up. Make sure everything is well secured and the leads are
correctly installed. (Runs nice, eh?)
Next step is to do the plugs. Start with the Bosch W8AP's. If they work for
you, fine. If not, try something else. It's your ride.
Gap them to about .040 The CDI module puts out enough juice to fire them up to
about .050 at cr's up to around 9:1 but the optimum gap has to do with your
compression ratio, mixture and so forth. Start with .040 then tinker if you
think it needs it.
Be damn sure to use a dab of anti-sieze on the threads of the plugs and that
the compression washer is in place. As per usual, install the plugs BY HAND
until the thread is full-depth. Don't put a wrench on those things until they
are fully threaded into their bores. And if you can't thread them in by hand,
you've got galled threads and need to do something about it -- it ain't gonna
heal itself.
Torque your plugs to 22 ft/lb with the engine no more than warm. (It's best to
wait until the engine is cold before removing the spark plugs. Try to remove
them from a hot engine, you'll gall the thread, not matter what the plug
manufacturer's say in their service bulletins.)
(This is the standard rule for aluminum heads... and has been since the 1920's.
The world is filled with engines having aluminum heads but about the only
folks who seem to have trouble with stripped spark-plug holes is kids with
Volkswagens. I wonder why that is...)
Fire it up. Runs a little better, eh? New plugs always give an engine a
boost.
Drive it a while. Think about it. If there's a problem of some sort, deal
with it.
Last step is to buy a Pertronix 'Ignitor' that fits your distributor. Pull the
distributor and install the 'ignitor'. Be careful of the wiring. One lead is
+12v, the other is the signal lead... it goes to the coil's negative terminal.
The ground is internal through the body of the distributor. (The +12v is for
the Hall effect sensor and some related circuitry. The triggering transistor
appears to be an SCR but Pertronix refused to talk to me about it... so I
xrayed one and took anothe apart with an abrasive blast. Looks like an SCR to
me. Before I put one on my bus I put one in a distributor body I coupled to an
electric motor. Then I let it run about 45 days. It was still working at the
end of my 'test', which emulated about 50,000 miles of use. So I felt
reasonably safe in using it. [Why test it? Because at least half the
after-market stuff for Volkswagens is junk, pure and simple. I didn't want to
get halfway to Cabo and discover it was a reed relay or mercury switch. And
since Pertronix wouldn't tell me what the circuit consisted of, I had to find
out for myself. Doesn't everyone do that? :-) ] )
Be sure to set the proper air-gap and make sure the Hall effect sensor (the
black epoxy cube on the aluminum plate) is standing square to the plate. I've
installed several of these and most were bent right out of the box due to
improper riveting. Easy enough to straigten but if you don't notice it the
thing can actually rub against the magnet-ring... not a good idea. (And yes,
it's 'magnet' not 'magnetic'. There are four high-strength magnets cast into
the nylon(?) ring that fits down over the cam-lobes of the distributor shaft.)
Make sure the magnet-ring is pressed FULLY down onto the cam lobes. There are
instructions with the Ignitor but the illustrations don't look much like the
real thing.
Put the rotor back on. (You can expect to wear out a rotor about every two
years due to the higher spark voltage. Just carry a spare so it won't leave
you stranded. Ditto for the cap.) Make sure the ROTOR seats fully. On some
distributors, you can't use the 'Ignitor' because the magnet-ring prevents the
rotor from seating full-depth. (But you can machine a bit off the lower edge
of the rotor, if you're careful doing it.)
Fire it up. Hey! Now THAT's a difference. Reason is, you've just eliminated
a lot of mechanical jitter that is present in most old distributors. The
jitter is still there but the triggering method used by the 'Ignitor' masks it.
No more points-bounce. In fact, no more points, period. Your plugs are now
being fired in response to an electronic signal that is far, far more precise
than any mechanical switching arrangement.
Slap a strobe on that puppy. And plug a sniffer up the tail pipe -- you can
lean that thing down by quite a bit, now that you've got a higher spark
voltage. Static timing okay? Then go ahead and kick it up to where the
advance is all in and check the max. Dial it back down to thirty degrees or
less. (I run 28. Yeah, I know. But I'm more concerned with getting there
than how fast I can get there.) Hot weather, bad gas, heavy load, crank it
back a bit more. And tweak your idle down -- better ignition has caused your
idle rpm to increase. Keep them between 800 and 900 rpm. Any slower and the
engine won't cool properly when you come off the freeway, etc.
Now you can let her cool down and do the valves. Of course, if you're running
swivel-foot adjusters you only gotta do them once a year or so.
Welcome to the 21st century. Odds are, you won't have to even TOUCH your
ignition system for the next two or three years. No more tune-ups.
What'd it cost you? Lessee... 90 for the CDI module, ten for the wires, eight
for the plugs (Kragan; two bucks a pop), 65 for the 'Ignitor'... about $175,
give'rtake.
Now here's what's gonna happen. Your mileage is going to take a nice jump.
Most folks report an improvement of 8 to 15 percent. Depending on how much you
drive, that alone will pay for the mods in about two years. But the driving!
Damn! The thing really DOES run better! That's because you've gotten rid of
points-bounce and shaft-jitter and incomplete combustion at higher rpms. And
that means your engine will last a little longer because your oil is going to
stay a little cleaner because there won't be so many unburned hydrocarbons in
the blow-by that gets into the crankcase.
Plus it's going to start better. A LOT better. And no more cross-firing during
damp weather. And your engine is running cooler, too! Those Corvair-type air
seals really make a difference.
I've been using such an ignition system for nearly thirty years -- it's been
available that long. I first wrote about it on the internet more than five
years ago... and immediately got a blizzard of flamers and hate mail -- lots of
kiddies shouting 'If it's really that good and really that easy, then why
haven't we seen anything about it in the magazines?'
Now that's a pretty good question :-)
The CDI module doesn't claim to be anything special, just a good basic ignition
system. Unlike the Jacobs, Compu-fire, etc., the little Universal CDI won't
work at 12,000 rpm nor with compression ratios higher than about 9:1. And I've
never seen one on the drag strip.
But if all you want is a good, reliable ride, it's the best idea since beer in
cans. It will save you money, help clean up the environment and make your car
run better, all at the same time.
Think about it. No more tune-ups. Engine that lasts longer and gets better
mileage... If everyone was using this system it would put a lot of
after-market suppliers out of business. No wonder you never read about it in
the magazines :-)
-Bob Hoover
Veeduber
>
>Bob,
>(snippity-snip, etc) Thanks for sharing your wisdom.
>John Spohn
John,
You're welcome.
The combination of a CDI module, silicon leads, better air seals, more durable
spark plugs and electronic triggering really DOES work. If you'll check the
archives of the various VW-specific mailing lists you will find messages from
people who have installed this exact system. One fellow claimed his mileage
jumped by 25% but I think he just needed a tune-up to begin with :-) Most
folks report a solid, verifiable 10% increase in mileage along with a spiffier
ride -- making it up hills in 4th that used to take 3rd, and so on.
There's no mystery to any of this. The system simply promotes better
combustion. All modern vehicles use similar systems. Porsche adopted such a
system in the late 1960's and I simply followed suit. My most recent change to
the system was to add the Pertronix 'ignitor' to replace the points. So far,
I've only used the 'Ignitor' for a couple of years so I still carry spare
points -- I do a lot of boondocking and don't want to find myself stranded.
I tried the optically triggered arrangement (also offered by Universal) but the
Bosch distirbutor doesn't have a very good oil seal -- there's always a bit of
oil vapor in the body of the distributor. Combined with the carbon granules
that wear off the 'button' in the distriubtor cap, the oily vapor & soot
eventually obstructs the IR sensor and produces false triggering. You can
clean the thing with a Q-tip & alcohol but you gotta pull the shutter to get at
it and are dead on the side of the road until you do. So I went back to points
and stuck with them until something better came along. Something I could
personally verify was better. Points, and a good distributor, are still a
viable option if you're strapped for cash, can't afford the Ignitor right now.
But the heart of the system and the real secret to the improved performance
comes from the CDI module, which works fine with the stock -- black -- coil :-)
The CDI module is an aluminum brick, about 3 x 4 x 6. In a bug, the handiest
place to install it is on the firewall in the upper left corner of the engine
compartment, just back behind the 'corner' of the blower housing. In an early
bus, make up a plate or bracket and install it on the strut to the left of the
engine. In a 'loaf', screw it to the overhead of the engine compartment, again
on the left (the coil is on the left side of VW engine installations). I've
never installed on on a Type 181 but lotsa folks have (see the Thing list
archives).
-Bob Hoover
chu
Good quality (MSD, Mallory, Accel, etc.) 8MM wires are fine but nothing
beats the looks of the Taylor 10.4 mm fatties.
Keith
Doug Calvin wrote in message <37EB0BAE...@funtv.com>...
>Could someone point me towards information regarding converting a
>standard VW ignition system to a capacitive discharge system? I'd also
>like to learn about related topics such as spark plug wire requirements
jbinc...@hotmail.com
since 1981 and never had a problem. About five years ago, added an MSD 5 (the
cheapest one), made a tremendous change in starting (just one click on the starter
does it any time) and went from 23 to 28 mpg.
TQuan
and you'll be in business. MSD system's have enough kick to send you to
another planet if you got shocked by it.
Searoy
my $300 allowance next month to a new wiring harness, maybe
a new coil, and maybe a swap meet carb.
And I usually get $100 a month, so it may be a while before
I can benefit.
--
*** Teach a Man to Fish ***
Searoy
Veeduber <veed...@aol.com> wrote in message
news:19990924032153...@ng-fs1.aol.com...
: >Could someone point me towards information regarding
Veeduber
> Would you care to address the
>question of #3 retard in a non-doghouse style upright? When the Petronix is
> installed, that retard goes away, right? I've heard the retard is
>needed to reduce
>heat/cracks etc in the #3 area of the case, even with a doghouse style
>cooler.
Jeff,
That's a good point, thank you for bringing it up.
I checked only two Ignitor magnet-rings. Both were symmetrical (ie, 90 degrees
-- no retard on any of the triggering magnets). This indicates that the
Pertronix 'Ignitor' should NOT be used with any VW engine still running an
internal oil cooler.
Volkswagen dropped the retard from their distributors in 1971 (?) when they
introduced the external 'dog-house' oil cooler. Given that the external cooler
is about 4X as effective as the old internal cooler, and that it is
retrofittable, it is an obvious mod to make. Since the 'dog-house' cooler has
been available nearly thirty years and is so much more effective, I'm surprised
to see folks still using the old style cooler.
I've never seen any need for retardation once the internal oil cooler is
removed from the blower housing. #3 ran hot because it got only pre-heated air
from the oil cooler. Once VW moved the oil cooler outside the blower housing,
the operatin temperature of #3 came down to the same as for the other jugs.
If you have ONE hot-running cylinder, check your tin-ware -- such problems can
usually be traced to a lack of cooling air or pressure, either from loose or
missing tin-ware or blocked fins near the exhaust.
-Bob Hoover