I have a mallory 25 duel point distributor that im going to rebuild . question is what is the condenser for and do i need to replace it or delete it? some one said it was for noise in the radio, but this is in my drag car ....so no radio.. also while were here , whats the deal with the pertronix converssions?
The PerTronix Conversion for the Dual Point Mallory's work very well. Have used a bunch of them. Keeps the old school look with a much more accurate, hotter spark and no points to Futz with. You can always keep the points in the glove box in the case that something shorts out the unit and you're back on the road
A lot of cars have a noise filter, or noise suppression capacitor that prevents radio noise. It looks a lot like a condenser, but is always located outside the distributor, the condenser is inside the cap. Maybe that's what you were thinking of.
The noise suppression capacitors are mounted on the device that makes the noise...usually the generator.
Madmaker go to the pertronix and you have answered all your questions etc.. good unit fairly cheap to convert and pretty reliable ...no fuss-no muss.. 440roadrunner, good use of my friend Jorge Mencu's scope pattern , however its really a lot simpler than you made it out to be. After 30 plus years of teaching igntion ( along side Jorge) i would say it like this: A car will typically NOT start without a condensor. The condensors function is to prevent a arc at the contacts points and allow a clean open shut with a clean on off of the primary current flow. This allows a clean break for the igntion coil buildup. The actual storage capacity of the condensor ( in mfds-micro farads) is a crutial design feature of each individual system. If the contacts are closed and current is flowing thru them ( 3-4 amps) and the distributor cam starts to open ( like .001 etc) the 3 amps would want to take the path of least resistance and continue to jump the gap. The condensor would allow a (fake) temporary place for this current to go allowing time to open the point gap even further ( maybe .018 etc), by the time the capicity has been reached in the condensor ( maybe .25 mfds) the gap is at its largest point ( .018) and it can no longer jump and the circuit is allowed a clean shut off of primary current. THEN we have a reverse problem. Now the condensor is charged to its max ( .25 mfds) and the contacts begin to shut , and this stored energy is allowed to be dumped to ground to start the cycle again. A condensor thats too low on the mfd spec ( .020 on a .25 spec) will arch when opening and a condensor thats too high .48 on a 25 spec) will arch when closing. Either of these will cause a performance problem or short life on contacts. A case in point : When building some of our conversions i test each capicator/condensor out of the package. I just tested a carton of 24 units from a major supplier and only could use 5 of the batch because almost non of them were up to spec. This condensor matching becomes even more of a ptroblem at higher rpm...... Hope this helps a little bit......... Jim Linder Linder Technical Services
Use Pertronics Ignitor ll , no need for a condensor but will need a hotter coil like a Flamethrower ll.
Most (if not all) Mallory dual point distributors have the condenser on the outside because there isn't enough room on the inside. That's a pretty good explaination 440Roadrunner.
Jim, I was surprised at your example of only 5 or 24 new condensor/capacitors being within spec. How do you perform the condensor test? Do you need special equipment or can the average gearhead test them with a power source and multimeter? Is there a downside to utilizing points to activate a remote HEI module or MSD CD ignition box? And would you still need a condensor in the circuit? Don
use a pertronix conversion, I or II,and one of their coils, so you don't have to worry about if you shudda used a ballast resistor. (and it will look retro) One day when your flush, buy a second module for a spare. You'll never need it. questions? call pertronix. Do they still make points? Do they still make osciliscopes? I'm retired, I don't care.
I know a neat way to test Capacitors.... It involves charging it up, your Budweiser and one of you gullible neighbors' tongue. have 911 on your speed dial.
You can do a simple test that will indicate the condenser is working, but perhaps not up to its rating. This works with an analog multi-meter and may work with a digital multi-meter, but I've never tried it with one of those. I suspect the digital multi's react too slow to make a successful test. Remove the condenser. (Makes it convenient, but you can leave it in the distributor if it's disconnected from the points.) With the condenser negatively grounded, touch the terminal end with positive 12 volts. Set your multi-meter on the proper voltage scale - 10V DC works for me, it won't sweep that high even if you charged the condenser at 12 volts. Ground the body of the condenser or connect the black (-) negative multi-meter wire to the body and touch the multi-meter red (+) positive wire to the condenser terminal while observing the multi-meter indications. If the condenser is bad the meter needle won't move. If it's good - or close to good - the needle will swing up and then back down as the condenser discharges. The needle swing will go perhaps 6-7 volts, but all you need is an indication so don't sweat how high the needle does swing. This will give you rough approximation of whether the condenser is good or not. You need a capacitor tester to do an accurate test, read the Mf etc. Condenser is just another name for capacitor....
Yes i have a couple of the ( once used every day ) Sun machine condensor testors that measure the leakage, load and actual MFD's of the condensor. A pretty specialized piece of equipment from the 70's. Using a set of contacts to activate a remote HEI module would greatly lower the actual current going thru the contacts , however i have used some of the circuits given ( on different web sites) and tested a few of them ( always looking for a better mousertrap) and found many fire the coil on the point close instead of the point open signal. ( this causes a rotor phasing and timing change that cant be overcome on some systems ( early flathead would be one working example). You no longer need the condensor as the contacts become a low ( miliamps) current draw...
what's the capacitor for?? the capacitor absorbs electricity fast, and give's it up fast. Way faster than the battery. don't let the diagram be confusing, when the points are closed the cap. looks shorted out to negative battery both sides. It's really charging thru the coil primary, when the points open the cap both goes fully charged and open circuit, but, the spark on the tip of the secondary isn't looking for negative battery, or just "metal", it wants the other plate of the capacitor best. if the block side of the points burn, the cap is too small in farads, if the cap side burns it's too big. learn that over 20,000 miles.
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