420 ignition system

country53 · Post by **country53** » Sat Jan 16, 2010 11:43 am

I installed a GM one wire alternator on my 420C. I converted it over to 12VDC negative ground. I also changed the igniton system to solid state. I got the kit from denny's carb shop and it included solid state breaker, magnet to go on distributor cam, thunder bolt coil, ballast resitor and wires, I furnished plugs H12 champions. After installing everything and timing engine at a fast idle the crawler started fine but it will not pull its own self in 2nd gear or higher and under a load it misses and sometimes it sounds like to blocks of wood spacking together coming from the engine. After kicking out of gear it will idle fine and start every time. Any one got any ideas what I might try next? The crawler was running fine when I pulled into the shop.

Paul Buhler · Post by **Paul Buhler** » Sat Jan 16, 2010 4:07 pm

Hi: Did you time to "Spark" or "TDC"? sounds like your engine is running with retarded spark to me. Hope this helps. Paul

country53 · Post by **country53** » Mon Jan 18, 2010 6:14 am

I timed the engine to shop manual specs, which is to spark at a fast idle(2150 rpm)

KenP · Post by **KenP** » Mon Jan 18, 2010 7:48 am

deleted

Post by **Lavoy** » Mon Jan 18, 2010 8:40 am

I would echo the sentiment on the Champions, I have had more bad ones than good ones, I no longer sell or use them at all.
Lavoy

joeturner1977 · Post by **joeturner1977** » Mon Jan 18, 2010 8:52 am

What is the spark plug that 9 out of 10 professionals choose ???
Just wondering I recently had my Champion H12 fail as well.

Stan Disbrow · Post by **Stan Disbrow** » Mon Jan 18, 2010 10:11 am

Hi,

I switched to AC's in all my 2-cyls long ago. The Champions would work OK for while, and then decide to misfire or worse, slow fire which leads to a loss of power without the obvious miss.....

Yet, those pulled Champions would work fine in other-than-2 cyl-JD engines. I never did come up with a good reason as to why they act like that. Oh, well.

You might also have some high voltage leaking inside the coil that wasn't too bad when it was 6v and points but is worse now after the conversion. That would alter the spark timing at the plugs, as the desired spark would be arcing inside the coil at the proper time, leaving a weak secondary spark at the plug some time after the first one stopped, making it retarded....

If it were me, I'd be changing that coil as my next troubleshooting step after changing the plugs....

Later!

Stan

Post by **Lavoy** » Mon Jan 18, 2010 2:39 pm

Just a thought, I notice you mentioned ballast resistor. The electronic ignitnion system I put in a 420 did not use a ballast resistor as far as I remember.
Lavoy

Tigerhaze · Post by **Tigerhaze** » Mon Jan 18, 2010 3:43 pm

Stan Disbrow wrote:Hi,

Yet, those pulled Champions would work fine in other-than-2 cyl-JD engines. I never did come up with a good reason as to why they act like that. Oh, well.

I have had similar issues with Champion H-10s and H-12s in my Ford 8N tractor; I will not use them in the 8N anymore and have switched to using Autolites. Thus I don't see it as solely an issue with JD gas engines.

Joe, since you changed out so many items in the electrical system, there may be other issues as well due to the retrofit. When you took apart the distributor did you make sure everything still moves freely? Did you switch to automotive plug wires instead of solid copper core tractor wires (I heard you can't use them with electronic ignition replacements)? Is the coil wired correctly? I think Lavoy is right about the ballast resistor, especially if a new 12V aftermarket coil designed especially for this engine (I think proper resistance is handled internally). I'm just lobbing ideas here to check.

Post by **Lavoy** » Mon Jan 18, 2010 4:38 pm

Copper wires are fine, no stereo to mess up.

One other thing to check on wires, if you do not have shielded terminals on the plug end, you could be shorting to the head.

As for plugs, I sell Autolite for the most part, otherwise AC.
Lavoy

country53 · Post by **country53** » Mon Jan 25, 2010 6:17 am

Thanks for the comments. I repaced the plugs with autolite machine would hit on both cylinders then but still didn't have any power. Checked the coil it was very hot to touch. Checked the module inside the distributor it wouldn't ever go to a dead ground it read infinity unactivated and 95 kilo-ohms activated. So I took the new modern ignition system off and went back with the old(replacing with new points condensor ect). Restarted and it was back to the fire breathing beast it always was. Thanks again for the help. The moral of the story is if it ain't broke don't fix it. Just go use it, something will break on its own.

Ray III · Post by **Ray III** » Mon Jan 25, 2010 7:08 pm

Yeah, there's no point in putting electronic ignition on these engines. The points aren't going to wear as fast as in a V8 car engine driven 20,000 miles a year, and they can't be beaten for reliability.

JDcrawlers Messageboard