Distributor capacitor (noise filter) modification

[wilfreeman]

Hi all,

I just finished posting the step by step for modifying (eliminating) the capacitor on m-series distributors. This is a good project if you either have a bad wire on your capacitor, or your capacitor is bad. I think they go for around $30 + shipping, so you can save some $$. If you have working radios installed, you might need to buy a new capacitor, because they were installed as a noise filter for radios.

Anyway, the writeup is located in my M38a1 blog:
http://wilfreeman.wordpress.com/

[jeeperjoe]

Nice mod! Capacitors dry out with age so any of those ~50 year old NOS ones aren't going to last long so this is much needed fix!

BTW read your blog. What kind of carburator cleaner did you use? The only thing that I can find locally is Berrymans at $30/gallon and it doesn't clean worth a hoot! I tried the internet recommended home made solution of equal parts alcohol, acetone and Xylene but it's didn't take ANYTHING off, not even loose grease

[jeeperjoe]

BTW do you know what the value of the original capacitor was supposed to be? I came across a lot of feed thru capacitors in my work and I may find one that will work in that application.

[wilfreeman]

Thanks! I try to put some step by step stuff on there - stuff that works for me anyway.

I didn't even look at the name brand - it is a gallon can with a small parts basket inside. Bought it about 15yrs ago. Directions say to soak the parts for 20 minutes - I ended up leaving them overnight. Still had to do a little scraping and wire brushing. Brake cleaner took the last of the stubborn stuff off.

No idea about the capacitor value - Wes might be able to tell you.

[wesk]

The elimination of that capacitor from it's small whole in the distributor has been going on for many years.

Mike's version has been in my photo album for several years:
http://www.willysmjeeps.com/v2/modules. ... _album.php



There are plenty of choices out there for noise filters with an adequate ratings if you are running radios or do not want to piss off the guy with a radio next to you.

For you early M38 owners the noise filter wasn't in the distributor. It was on the firewall and those firewall units and their proper cable are still available and reasonable.

A substitute noise filter can be installed anywhere along wire #12.

[capescw]

Just a cautionary note for some readers, the capacitor referenced is NOT the one across the points, internal to the distributor.

While the capacitor in the ignition primary circuit does help to eliminate some RF noise, it's primary function (and a necessary one) is to eliminate or reduce pitting of the points in a conventional ignition system, as well as aid in the spark quality. See this post for an excellent description:
http://www.historicwinton.org/Ignition%20Condensors.htm

Just my 2 cents worth...

[whydahdvr]

I'm curious, if the radio isn't powered by the jeep does it still need the capacitor fix here? I've been thinking of carrying my Rino 530CHx handheld radio.
Thanks.

[wesk]

The shielding on the plugs and the capacitor in line with wire #12 have the primary purpose of filtering ignition noise. The capacitor in the voltage regulator has a primary purpose of filtering generator noise. Any failures or deletion of filtering equipment will usually result in noise in on board radios weather powered by the jeep's electrical system or not. The only way to be sure is to try it. Radios vary in their built protection for RF noise.

Again, to insure clarity the capacitor in this discussion is in the distributor at the screw on connector location for wire #12 and is not the capacitor normally referred to as a condenser on the distributor point mounting plate.

[wilfreeman]

Yep, I saw Mike's picture of his conversion, but didn't see a how to about it. For people like me, I like to have a good idea of what I'm doing before I actually get into it. Now that I've done it, I see I could have just cut the rear cap off (all the way through), taken out the fiber material(?), and soldered the new wire to the post with a butt connector - then put some shrink tubing over that. It would have looked cleaner (like Mike's). I also left more of the case on mine so that I could still use the o ring for sealing.
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