TheSamba.com :: View topic - Keep condenser if using points to trigger CDI?

Wed Jan 02, 2013 11:26 am

Using stock distributor (034). Since points will have much less voltage across them just to trigger CDI, do I keep the condenser attached to the wire that goes to points? Instructions just say to "connect to points." Called CDI company and tech went back and forth before saying to just keep condenser. If any one has experience with this and knows for sure, I would appreciate it.

I realize I could go with a pointless solid-state pick-up to trigger CDI, but tried some several years back and had failure problems - and I wasn't the only one - so went back to points with no problems. Besides, even occassional "fun factor" shifts will only be around 5000 RPM, so I'm not concerned with points bounce and points make setting initial timing of the engine a snap.

Thanks.

Wed Jan 02, 2013 2:34 pm

You shouldnt need the condensor.

Wed Jan 02, 2013 2:42 pm

You may not need it.. but leaving it doesn't hurt either.. as it is not doing anything near what it was intended for with the CDI controlling the coil..
so leaving it is fine.. and at least it will be there if something goes wrong with the electronic ignition and you have to go back to it to get back on the road..

I guess the catch 22 is CDI boxes work much better with Low ohm coils and points and condensors don't ..

so it depends on your setup if you can go back to it if something happens and you need to get back on the road ASAP.

my .02

Wed Jan 02, 2013 2:42 pm

You don't need it.

Wed Jan 02, 2013 3:35 pm

In a points type ignition system, the condenser absorbs the inrush energy that travels thru the points to the ignition coil. The car would run fine without it but the points would arc and spark alot and wear out quite rapidly.
In the CDI system it is acting as a simple switch and little current flows thru it. So no need for the condenser.

Wed Jan 02, 2013 6:39 pm

Thanks for the quick responces. Tommiebsmith mentioned the coil and mine is a MDS Blaster 2 with lower ohm rating than stock to work better with a CDI. Sounds like the best thing to do is wire the CDI directly to the points and keep a points and condenser set in the emergency road box in case the CDI fails. If the CDI does go out I'll just need to fix it before the lower impedance coils burns out the points and condenser.

While you can open the spark plug gap up to about .04" with a CDI, I just read that keeping the stock gap is much easier on the secondary ignition system and you still get the same benefits of better starting, MPG and plug life. Any ideas on this?

Thu Jan 03, 2013 7:57 am

Quote: In a points type ignition system, the condenser absorbs the inrush energy that travels thru the points to the ignition coil.
I don't think so jimmy. When the points are closed the condenser is shorted by the points. When the points open and the magnetic field collapses to 'fire' the plug some of that energy 'heads' towards the points. The condenser 'absorbs' that energy so that the points won't arc over like the spark plug.

Thu Jan 03, 2013 9:26 am

Thu Jan 03, 2013 9:55 am

JSB wrote: Thanks for the quick responces. Tommiebsmith mentioned the coil and mine is a MDS Blaster 2 with lower ohm rating than stock to work better with a CDI. Sounds like the best thing to do is wire the CDI directly to the points and keep a points and condenser set in the emergency road box in case the CDI fails. If the CDI does go out I'll just need to fix it before the lower impedance coils burns out the points and condenser.

While you can open the spark plug gap up to about .04" with a CDI, I just read that keeping the stock gap is much easier on the secondary ignition system and you still get the same benefits of better starting, MPG and plug life. Any ideas on this?

the Blaster2 is like .3 ohms.. if you go to NAPA or someplace and pick up a 1.4 Ohm external ballast resistor or close .. you can add resitance back to the setup and run the condensor all the way till you fix the CDI.. something maybe purchased and setup with easy connectors to put in place on the side of the road with no tools.. remove the controlling wires from the CDI to the coil.. hook up the trigger (Condenser/points) wire to the NEG of the coil.. and the key power that turned onthe CDI directly to resistor then to the + of the coil.. should get you back up and running.

I think the gap idea used to say open it up depending on COmpression but lately most people on board with it does very little for performance so it is best/easiest to leave it alone.. PLUS opening would hurt the idea of being able to remove the CDI on the side of the road and get back up and running under 5 minutes.. with no tools.. :)

this all has been my experience when my first 6AL box died going down the interstate.. just trying to source the issue took longer than the fix.. since I had a blue coil at the time and 009 with a compufire. I wouldn't of thought
the box would of died.. but it did..

NOW 8 or so cars later and many MSD setups.. that has been the only one..
the Blaster2 is perfect (mount it upright) and I run a full MSD iginition with plugs gapped at 28 I think.. heck it has been forever since I've messed with it..

Thu Jan 03, 2013 10:42 am

It doesn't hurt to leave the condenser installed. If you need to bypass the CDI and revert to points you are already setup that way. I ran with and without, the spark from the CDI is the same.

Thu Jan 03, 2013 12:49 pm

Thanks again for the feedback and cleaver ideas to set the CDI up to bypass it should it fail- with the Blaster 2 coil the instructions do say to add a 0.8 ohm ballast resistor to the coil positive side if just running stock points/condenser.

Tommiebsmith, one last question: you said to mount the Blaster 2 coil "upright" and I noticed the instructions recommend it as well. Do you mean with the plug wire or "top" pointing up? I currently have it sideways since it fits much better that way - will this create a cooling issue for the coil?

Fri Jan 04, 2013 10:42 am

the coil has a air pocket inside it.. from what I gather it is for cooling..
and they suggest it upright for it function the way it was designed..

You can hear it in the coil..

I do it just because.. they say so.. and it has always worked well for me..

DO hundreds of thousands of millions of other people follow the directions??
NO... do theirs fail..??? 99% of that answer is NO..

so go figure.. I see so many people use them side ways.. with dual carbs with the fuel pump coil relocation mount.. I see plenty more use them upside down in the stock coil location and apparently they all still run today..:) and this is just a VW related response. MSD coils are used everywhere..

I guess.. I am saying I don't have your answer... I just do one thing and it seems to work well for me..

Hopefully you have awesome results with your setup and you enjoy your ride.. as that is really what makes it all worth while.. :)

Fri Jan 04, 2013 12:57 pm

runamoc wrote: Quote: In a points type ignition system, the condenser absorbs the inrush energy that travels thru the points to the ignition coil.
I don't think so jimmy. When the points are closed the condenser is shorted by the points. When the points open and the magnetic field collapses to 'fire' the plug some of that energy 'heads' towards the points. The condenser 'absorbs' that energy so that the points won't arc over like the spark plug.

Sort of.

A automotive coil is a kind of crappy transformer with a small magnetic core in a cooling bath of oil.
What happens is that when the points close the current rushes into the primary coil and is absorbed into the core and windings of the transformer as it builds charge and the voltage minus whatever current is used continues out of the transformer into the points then ground. When the points open, the field collapses and induces the flux into the secondary coil and out into the sparkplugs.
The current is dependent on the load. If the distributor is engaging the sparkplug then you will get a level current flow into the secondary.
If the distributor is not engaging the plug then you will get a low current then an over current situation as the core reaches saturation too quickly.
You need to keep the inrush current level. When the transformer reaches saturation it will basically short and draw lots more current than it is designed for. This is a typical VW problem. Bad compression in a cylinder or a cylinder not firing and the coil goes into saturation 25 percent of the time and eventually overheats and the car stops running and needs to sit and cool down for a while.
But back to the condenser. It absorbs the current flow when the points open to prevent arcing of the points. The only current in the circuit is the current from the battery thru the coil and to the points. This is a DC device. not a ac device. The flux created by the points opening and closing is the MMF or magnetomotive force. This force is induced into the secondary as magnetizing force and is either drawn away thru the spark plug or converted to heat if there is no discharge. It is not there to travel back thru the points.
Got it?

Fri Jan 04, 2013 2:51 pm

The air pocket in the coil is to allow for expansion of the oil - if it weren't there the top would blow off or the sides ballon when it gets hot (or maybe just leak.)

The oil serves two purposes - it conducts heat away from the windings, and it provides electrical insulation. If the coil is mounted sideways both these characteristics are probably preserved, but the likelyhood of the oil leaking under pressure increases.

We don't have enough data to establish if more coils actually do fail in this configuration than the correct upright mounting, but I have also seen a number mounted upside-down, and they were on apparently running engines!

Fri Jan 04, 2013 10:23 pm

Jimmy111 wrote: runamoc wrote: Quote: In a points type ignition system, the condenser absorbs the inrush energy that travels thru the points to the ignition coil.
I don't think so jimmy. When the points are closed the condenser is shorted by the points. When the points open and the magnetic field collapses to 'fire' the plug some of that energy 'heads' towards the points. The condenser 'absorbs' that energy so that the points won't arc over like the spark plug.

Sort of.

A automotive coil is a kind of crappy transformer with a small magnetic core in a cooling bath of oil.
What happens is that when the points close the current rushes into the primary coil and is absorbed into the core and windings of the transformer as it builds charge and the voltage minus whatever current is used continues out of the transformer into the points then ground. When the points open, the field collapses and induces the flux into the secondary coil and out into the sparkplugs.
The current is dependent on the load. If the distributor is engaging the sparkplug then you will get a level current flow into the secondary.
If the distributor is not engaging the plug then you will get a low current then an over current situation as the core reaches saturation too quickly.
You need to keep the inrush current level. When the transformer reaches saturation it will basically short and draw lots more current than it is designed for. This is a typical VW problem. Bad compression in a cylinder or a cylinder not firing and the coil goes into saturation 25 percent of the time and eventually overheats and the car stops running and needs to sit and cool down for a while.
But back to the condenser. It absorbs the current flow when the points open to prevent arcing of the points. The only current in the circuit is the current from the battery thru the coil and to the points. This is a DC device. not a ac device. The flux created by the points opening and closing is the MMF or magnetomotive force. This force is induced into the secondary as magnetizing force and is either drawn away thru the spark plug or converted to heat if there is no discharge. It is not there to travel back thru the points.
Got it?
It's been a long time since I've read so much BS in one post. :lol:

Sat Jan 05, 2013 5:05 am

Rubbish! This is The Samba, such BS is very common here.

The guy is at least trying, when he continues in his understanding of physics he might get it together.

Sat Jan 05, 2013 8:48 pm

I called MSD Friday about the mounting question, but they are closed for the holidays. After seeing your responces I did a quick Google and other sites state same thing - recommended mounting upright because if mounted sideways "air bubble" can uncover some windings from the cooling oil causing coil to overheat, but many, many have run it this way for years with no problems - though many of these people did recomment making sure the coil terminals are not in the 12 and 6 o'clock position since the one on top could have limited cooling oil contact.

Others have also run upside down with no issues but warned some coils can eventually leak at terminal seal and then oil would be lost.

Sounds like if everything else (ground, spark plug wires, etc.) are in good working order you decide how luck you feel about not mounting it upright.

Might just keep it on its side for now and put an old spare coil in the road kit along with my quick-connect back to points and condenser set-up and just enjoy the drive. Or there's always the epoxy filled coil where mounting position is a non-issue.

Thanks again for your help.

Sun Jan 06, 2013 1:49 pm

Quokka42 wrote: Rubbish! This is The Samba, such BS is very common here.

The guy is at least trying, when he continues in his understanding of physics he might get it together.

Well, I do have piece of paper from Henry Samueli in UCI that says I learned physics and Electrical engineering. I even specialized in Magnetism. I Learned things like Teslas, gauss, oersteds and henrys. and Maxwell is my friend. :D , ... And I did work for RCA for a time designing Transformers and well vacuum tubes..... But Well, yes I dont know anything. :D
Like I say all the time, believe what you want.

Sun Jan 06, 2013 2:22 pm

Maxwell... friend? :shock: so which circle of hell is your neighborhood?

Sun Jan 06, 2013 2:46 pm

Quokka42 wrote: Rubbish! This is The Samba, such BS is very common here.

The guy is at least trying, when he continues in his understanding of physics he might get it together.

You don't know enough to formulate a proper question........so you insult him instead? what's the point of that?

I'm glad to have Jim back with us, lets have some respect