420 running issues, spark, battery, points?

gohammergo · Post by **gohammergo** » Sun Feb 02, 2014 4:44 pm

It does Hertz, Hertz like heck! Especially at 60 cycles per minute, which approximates the beating of the heart and is what makes household current so dangerous!

I go past a Napa center on my way to work and I'll stop in and ask about the points. I do have a condenser that I can put on and see if that makes it any better.

I'll also clean all cables and such and make sure the contacts are good and tight. I hadn't given this much thought until now.

My father in law had mentioned installing a 12 volt battery and dropping voltage with a resistor. I didn't give it much credence at the time. Is there any benefit to doing this?

Thanks again for taking the time to read and respond. Seem to have quite the pool of knowledge here and quite the sense of humor too!

Stan Disbrow · Post by **Stan Disbrow** » Sun Feb 02, 2014 5:22 pm

Hi,

This is true. If the capacitor cannot suppress the back-emf from the primary side of the coil, there will be a secondary spark at the point contacts with associated pitting for sure.

I was thinking the condenser was replaced along with the points, but I don't see that stated after rereading the thread....

Stan

gohammergo · Post by **gohammergo** » Sun Feb 02, 2014 7:18 pm

I did replace the condenser both times I replaced the points. I also put on a new rotor the last time and new solid strand wires. Would have put a new cap on too, but they didn't have one. New spark plugs too. When I stop at Napa, I'll see if they have a cap too.

I was going to go out and try a different condenser tonight before dark, but I sat down by the wood stove and promptly fell asleep!

Post by **Lavoy** » Sun Feb 02, 2014 9:26 pm

I have caps on hand if you need one.
Lavoy

gohammergo · Post by **gohammergo** » Sun Feb 02, 2014 9:33 pm

Do you have the proper points too? How much for a cap, points and condenser. I already have a new rotor and wires.

I looked around the site some, but not extensively, do you have a lot of parts for these machines?

Post by **Lavoy** » Sun Feb 02, 2014 9:35 pm

About $18 for cap, rotor, points, condenser + freight.
There is a parts page on the main site, but it lists only a small amount of what I have available.
Lavoy

gohammergo · Post by **gohammergo** » Sun Feb 02, 2014 10:17 pm

what would the shipping be to zip 49935 for the parts mentioned?

Do you also do pin and bushing of tracks? Do you have pads available too? My 420 has pads that are I think 14" and some that are 12". My 430 has the wider pads, but I don't want to rob anything from that one.

gregjo1948 · Post by **gregjo1948** » Mon Feb 03, 2014 12:13 pm

Maybe the bushing in the distributor is worn enough that the points are changing their gap and causing excessive wear. Give the points shaft a wiggle to check for slop. gregjo1948

Tigerhaze · Post by **Tigerhaze** » Mon Feb 03, 2014 12:31 pm

Although I don't have a 420, I have worked on electrical issues on my 8N and have had symptoms similar to what you describe. I tried many of the things you describe (points, condenser, coil, etc.) and still had the intermittent spark issue. On my 8N it ended up being two issues in tandem:

1) Bad insulator bushings on the distributor housing (key 41 and 42) that is the stud for the coil to distributor wire (key 52): page 105-17 for the 420 parts manual (PC0505)

2) Bad ignition switch (key 17) or wiring connecting the ignition switch (key 20): Page 105-12 of PC0505

If your other major ignition components test OK or are replaced and you have the same symptoms, I would definitely check those out. It took me weeks to figure that out for my 8N.

EDIT: These issues also caused excessive wear on the new points I had just installed to try and remedy the issue; not exactly sure why that was but thought I would mention that as well.

Post by **Lavoy** » Mon Feb 03, 2014 4:31 pm

Maybe $8-9 freight.
Yes, I can rebush tracks.
I am very short on pads right now. Looking at making new ones, but that is a ways off.
Lavoy

original possum · Post by **original possum** » Mon Feb 03, 2014 9:53 pm

Not sure on the 420 and can't open the .pdf's on the JD parts site to see the 420, but my 40C has a resistor on the back of the ignition switch and a switch that operates off oil pressure. When you pull the starter it bypasses the resistor and takes power from the post on the starter. When you let go it stops that path and the current flows thru the resistor and pressure switch to the coil. (This path does not turn off while you start it, it is still there while cranking,) Unless the pressure switch is bypassed, there is a resistor in the line to extend point life. I've hotwired mine to bypass the resistor and switch and simply replace points more often.

vtjoe · Post by **vtjoe** » Tue Feb 04, 2014 7:46 am

you need adobe pdf file reader..... free download

Post by **Lavoy** » Tue Feb 04, 2014 8:04 am

Resistor on ignition switch is for dim headlights, has noting to do with the ignition circuit.
Oil pressure switch is for hour meter operation. If yours varies from either of these, it is not a factory installation.
Lavoy

original possum · Post by **original possum** » Tue Feb 04, 2014 12:19 pm

Sorry. Must've been on the voltage regulator. It's been a long time.

Stan Disbrow · Post by **Stan Disbrow** » Tue Feb 04, 2014 1:34 pm

Hi,

The resistor on the VR sets the point for the voltage relay to open and close the field coil feed to the generator. As that relay opens and closes, it kicks the generator output up and down to hold the battery at full charge voltage (which is in the region of 7.5 volts).

If a machine has been converted from 6v to 12v, then a resistor needs to be added in the ignition feed line. Did someone do that and then return the machine to 6v and forget to remove said resistor?

Stan

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420 running issues, spark, battery, points?

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