KEC-440/21 converting to CDI? I have searched...no luck.

[kentuckydiesel]

Hey guys,
I just traded an old golf cart for a fairly clean 1973 JDX8. Unfortunately, someone before me must have pulled it out of the barn it was in, tried to start it, broke the recoil spring, then left it out long enough for the recoil housing to fill with water.

The recoil assembly is salvageable (with a new rewind spring), but the whole stator/points plate assembly appears to be junked. With that, I am going to assume the timing advance isn't going to function properly due to the rust.

I will be making a flywheel puller today so I can see exactly where I'm at with this stuff, but in the meantime, I'm almost positive I'll have to replace the flywheel assembly and stator plate assembly. With that, it seems logical to go with a CDI setup rather than the old points style (I've read they are no fun to get dialed in). Problem is, it seems that there were so many different CDI parts out there, I can't seem to tell which will work for my application. I have even heard of people using Kawasaki CDI boxes, as I guess they are better?

So...

To start out, I assume I'll need a matching, CDI specific, stator plate and flywheel. Is this correct? If so, will any version of the KEC-440 swap?

CDI box? What are my options, and what is the best route to take here? What about going with new solid state ignition modules?

Ignition coils? I have never changed out coils before when converting from points to electronic ignition. That said, It seems that many frown upon this with the coils on these sleds...something about them not being up to the task of the CDI system? I can imagine not getting as hot a spark with lesser coils, but I don't know how the coils could be damaged by CDI.

Also, I know the CDI engines had heads for long reach spark plugs. I do have to wonder if this would be required anymore due to all the new spark plug technology.

Sorry for asking all these questions in my first post. I have tried to search for the answers because I know this has been discussed before, but it seems that most/all of the informational links that people have provided over the years are broken.

Thanks,
Phillip

[kentuckydiesel]

Think I just answered one of my own questions...the 3/4" reach plugs were used because they were resistor style, which reduced electrical noise.

Thanks,
Phillip

[harleysportster]

Phillip,
Welcome aboard. There is not much activity on here this time of the year for info but it will pick up soon. The little bit that I know about the change over from points to cdi is that you should be able to do it without much difficulty. Back in the day when the CDI first came out on the /22 engines, the mechanics didn't fully understand it and some switched back to points, so going forward should be easy with all the parts. You will need:
cdi stator
cdi box
cdi style external coils
cdi style flywheel
I am not sure if the /22 cdi flywheel fits inside of the fan tower.
Installing the electronic ignition is a step forward / good thing but it may be cheaper to replace all the damaged oem parts that you have unless you find a donor engine.

[400brian]

I believe the reach of the plugs has more to do with the thickness of the heads.

[Matt]

I believe the reach of the plugs has more to do with the thickness of the heads.

Correct, the resistor plugs have nothing to do with the length. CCW switched head depth/plug length in '74 I think?

So for the CDI setup, you could find a complete ignition system off a parts Cyclone or 70s Liquifire or even '75+ 400 to swap. If you are really serious about having a reliable sled, you can buy NEW Hewtech CDI and stator here: http://www.cdibox.com.

[400brian]

CCW switched head depth/plug length in '74 I think?

That is my observation. '72 and '73 engines used the short reach plugs. In '74, the /5 and /22 engines had more fin area on the jugs and heads, and the longer reach plugs became the norm after that.

[kentuckydiesel]

I believe the reach of the plugs has more to do with the thickness of the heads.

I was thinking it was the other way around...they changed head thickness to go with a 3/4" resistor type spark plug. As far as I know, there is (or at least wasn't at that time) any such thing as a 1/2" reach resistor type spark plug that would have worked for the earlier style heads.

I pulled this from the SM-2100 Manual:

Spark plugs for snowmobiles vary in reach ; they
are either 1/2 inch (12.70 mm) or 3/4 inch (19.05
mm). Of the snowmobiles in the 1972-1973 John
Deere Snowmobile Spark Plug Chart, only the JDX4
Snowmobile uses a 3/4-inch (1 9.05 mm) reach
plug'-all other machines use a 1/2-inch (12 .70 mm)
reach plug.
All snowmobiles in the 1974 and 1975 John Deere
Snowmobile Spark Plug Charts use 3/4-inch (19.05
mm) reach, resistor-type spark plugs. A reSistor-type
plug does not reduce firing-tip voltage but does minimize
radio and television interference generated by
the ignition system.

Regarding that Hewtech deal, I had looked at that site before...saw alot of recommendations for their products...but it seems they only have replacement parts for the original Deere CDI stuff. Is this correct? So I could get CDI and stator through them, but I have to convert the rest of the mechanical parts over just as if I was doing a stock CDI conversion?

Thanks,
Phillip

[harleysportster]

Phillip,
Hewtec specializes in CDI ignition replacement. His fire Plug cdi replacement for the oem Prestolite is tops. There are very few, if any failures and he offers a warranty. He does not manufacture anything to do with the points systems. At first he made the cdi boxes, now he handles rewound stators as well. There is a core charge if you do not have one. Flywheels, Timing rings and even good used external coils show up on Ebay or in classifieds.

[kentuckydiesel]

I gotcha.

I also did some checking on deere parts catalog to see what would work, and what wouldn't.

I guess this is the only question I have left:

I have seen some people recommending an upgrade to the Kawasaki CDI system on the CCW engine. Any thoughts on that?

Thanks again. I really appreciate all the input.

-Phillip

[harleysportster]

Personally, I have never heard of that conversion, but I do not read many others forums.

[tiny73]

You will also have to change your tachometer. If you can find a complete KEC 440/22 you could swap out everything you need

[harleysportster]

FYI, the cdi setup from 77/78 are more reliable than the 76 or earlier. The 340/440 are the same. You can even use one from the /23 liquid cooled engines.

[Matt]

I believe the reach of the plugs has more to do with the thickness of the heads.

I was thinking it was the other way around...they changed head thickness to go with a 3/4" resistor type spark plug. As far as I know, there is (or at least wasn't at that time) any such thing as a 1/2" reach resistor type spark plug that would have worked for the earlier style heads.

Phillip

They certainly do now, for example NGK BR8HS (R is resistor, HS is the 1/2" reach). But your right, the original recommended plugs weren't resistor, so maybe that was the reason. I figured the head change was for improved heat dissipation or something like that.

[kentuckydiesel]

FYI, the cdi setup from 77/78 are more reliable than the 76 or earlier.

That's a good thing to know. Were the 75 conversion, 76, 77, and 78 all Prestolite, the later having updates, or did they switch suppliers for 77-78?

Thanks,
Phillip

[harleysportster]

They were all Prestolites, with an update/ improvement in '77.