Datsun Roadster Forum-311s.org

Good evening all. I noticed the other day that the wire on the condenser that's mounted to the side of the distributor is not connected to anything. Engine had less than 100 miles on a rebuild when I bought it. I'm guessing it was not attached during the rebuild. (like the belt for the smog pump was not put back on....Had to find one to fit so it would pass Texas emissions test) What does the wire attach to? Points inside the cap? Doesn't affect the running of the engine but I remember from automotive classes that it can reduce the life of the points. Last vehicle I had with points was a '73 Mazda RX-3. Twin distributor, one single point, one dual point. Never did anything but change the points out once but I don't remember where the condenser wires went, or if it even had them. But the Rotary evidently scared my instructor for engines in Jr. College to death. (While we took the written final, he had all our cars in the shop and messed up something on everyone of them. Had to fix it and drive it out to pass that class back in 1975! All he did was swap 2 coil wires and two spark plug wires. I think he was scared to mess with the Rotary engine!!!!) Thanks for any insight you can give me.

As I understand it they are required and protect the points. One that is not working correctly will pull spark from the points and cause erratic ignition, so they do need to be in proper working condition. The spade slides under the screw attached to the same plastic and metal part as the points as I recall but on the outside of the dizzy (sorry, no dizzy on my car for many years, modified, so others may need to confirm).

As per piccy below:-

Welcome to the forum, CK.
(1) The long condenser on the side of the distributor (or in some cases mounted on the firewall) is there only to prevent radio interference and does not affect the running. The short one mounted to the bottom of the distributor is critical.
(2) Texas vehicles older than twenty five years are exempt from emissions testing, even in those counties (like Tarrant) that require them.

Jon

jhayden wrote: Fri Jan 10, 2025 7:49 am Welcome to the forum, CK.
(1) The long condenser on the side of the distributor (or in some cases mounted on the firewall) is there only to prevent radio interference and does not affect the running. The one inside the distributor is critical.
(2) Texas vehicles older than twenty five years are exempt from emissions testing, even in those counties (like Tarrant) that require them.

Jon

Thanks Jon and Greg! I knew the engine ran fine, just saw the loose wire and wondered about it since my Mazda didn't have one on the outside of the distributors. If I ever do anything about an audio system in it (seems to be a stupid idea, as listening to this little car winding through the gears is the best ear candy around!!!) I'll hook it up.
On the Texas emissions, no... pre OBDI cars (91 through 98) don't have to be tested (I worked as a Service Advisor at 5 dealerships over 17 years starting in 1999 and only the first one had a dyno with their inspection machine that even could test older cars with the OBDI systems) but the emissions equipment does have to be hooked up in cars built starting in 1968. That was the first year cars had emissions equipment in the US.
Have a great weekend, everyone!!

PS. Jon, did you get any sleet/snow/freezing rain in Tyler? Snow quit here (an inch or so on top of the sleet base) about 9:00 last night.

Yes, the condenser essential for points function is located at the bottom of the distributor on our cars, unlike those contained underneath the cap as in most vehicles.
No, we were fortunate this time: no freezing precip here in Tyler!
Effective this month (January 2025) Texas no longer requires annual safety inspections for autos to renew registration. (Fewer than a third of US states currently require such inspections.) Emissions inspections are not required for our cars (regardless of county of residence), so you should not have any inspection of any kind necessary next time your registration comes up for renewal.
Let me know if this is in error.
Jon

If I remember correctly, the wire screws into the screw on this, found on the side of your dizzy.
.

Here's a pic of Datsun 1200 distributor. Case of condenser is the ground through the distributor body and wire goes to the plastic insulated piece where the blue arrow points (same as what Greg shows in his post)

Coolmeadow Kid wrote: Thu Jan 09, 2025 9:04 pm Doesn't affect the running of the engine

Only the first of the condensers pictured affects the running of the U20 engine, and does so GREATLY! The other is essential only for preventing AM radio static.

Jon

The little condenser / capacitor / instant battery ,evens out the current to the ign coil and is a good idea, current flows from the condensers to the pos side when the points break the coil looses energy to magnetize/ energize it ,but of course that's a fraction of a second. the small conds.saves a bit on the points
as the spark/amps of reconnecting is reduced ,that stops radio static .
Per My training instructor at Nissan
A test is at night very dark has someone crank the engine with the cap off see the points spark then disconnect the condenser at the coil see ,the spark increases

Yes red is correct on the little condenser, also known as a capacitor. A capacitor looks like an open circuit to DC signals and looks like a very low impedance (think resistance) as the frequency of the signal applied to it increases. Essentially the impedance goes down as the frequency goes up.

There is a lot of electro-magnetic noise (EMI) in cars, especially older cars. Any oscillating signal (i.e. Frequency) on the DC voltage lines is noise and the capacitor dissipates the noise signal by pulling it down to ground. The small condenser it is filtering the frequency "noise" on the DC voltage to the coil. The condenser on the distributor does the same thing for another reason. When the points open a fast rising (i.e. high frequency) high voltage spike is developing in reverse polarity (back EMF) to the coil's secondary voltage. The condenser shorts this voltage spike to ground before it can get high enough to arc the points. The secondary of the coil looks like a large impedance to the fast-rising back emf. So, if the condenser wasn't working we would have a large voltage forming across the open points which would arc and likely blow a big hole in the point's contacts.

For the best EMI noise protection for audio and other electronics on board, an inductor in series with a capacitor to ground on the DC supply lines is a very effective filter for unwanted and sometimes damaging EMI. These filters are readily available on line. https://www.amazon.com/dp/B07CWSYWM4