Spark Plug Z4C/Z8C: What's the Diffy?

[rohmell]

Some kits come with a Z4C spark plug, some kits come with a Z8C spark plug.
They both cross-reference to the same thing, so why the difference in the numbering?

 

[Al.Fisherman]

Some kits come with a Z4C spark plug, some kits come with a Z8C spark plug.
They both cross-reference to the same thing, so why the difference in the numbering?

Both are candidates for the trash can, along with the high voltage lead. Get a good plug like a NGK and replace the lead.

With Chinese (SINO) plugs the higher the number, the colder the plug. Z8C is colder then the Z4C plug.

Z...Thread and length in mm. 14mm X 1.25
4 or 8....heat range...8 being colder then the 4
C...Type of electrode, in this case copper core.

Did that answer your questions?

 

[2door]

Al,
Just curious why you always suggest to replace the high voltage lead. The kit supplied one, solid metal conductor, is better than what you'll get at most auto parts stores today. Everyone I've seen, with the exception of copper core on bulk rolls, is resistance wire. And not high performance wire either just standard old carbon impregnated thread as a conductor which doesn't lend itself well to the screw in CDI connector.

Don't believe me? Try using a good ohm meter, test the kit wire against the same length of auto parts store wire. Our little underpowered ignition systems need all the help they can get and that doesn't come by adding resistance to the high voltage side.
Tom

 

[rohmell]

4 or 8....heat range...8 being colder then the 4

The heat range numbers are clear, but it seems that the Chinese are not following that convention.
This chart shows both types on the same line, as if they are the same:
Spark Plugs|spark plug|K6TC|A7TC|F5TC|E6TC|D8TC|Z4C


In response to 2Door's comments, I think that it is a stretch to even call them a spark plug wire or or ignition cable. To me, they look more like a plastic tube or hose with a couple strands of copper wire shoved thru 'em. Although I never tried it, I think a piece of brake cable housing (with a steel inner lining) would work better that what is supplied with the kit, plus it already has a hole in the center, ready to accept the CDI screw.

 

[Al.Fisherman]

Al,
Just curious why you always suggest to replace the high voltage lead. The kit supplied one, solid metal conductor, is better than what you'll get at most auto parts stores today. Everyone I've seen, with the exception of copper core on bulk rolls, is resistance wire. And not high performance wire either just standard old carbon impregnated thread as a conductor which doesn't lend itself well to the screw in CDI connector.

Don't believe me? Try using a good ohm meter, test the kit wire against the same length of auto parts store wire. Our little underpowered ignition systems need all the help they can get and that doesn't come by adding resistance to the high voltage side.
Tom

I don't use resistance wires....not good for our application.
19 strands with Rajah clips. How many strands are on the stock wire..what...about 14? My first kit had about 6. Stock wire is encased in cheap rubber or the sorts. The Hypalon (made in the US...Kansas) is encased in a "insulator" and in rubber. I know that rubber is a insulator. The more efficient the wire the more spark energy is transferred to the spark plug, and the Chinese wire is less efficient. Attested by the items they make.

The heat range numbers are clear, but it seems that the Chinese are not following that convention.
This chart shows both types on the same line, as if they are the same:
Spark Plugs|spark plug|K6TC|A7TC|F5TC|E6TC|D8TC|Z4C

The chart is for "recommend" replacements and don't take heat range into consideration. Those plugs are 14mm and have a reach of 11mm or 7/16", so the physical plug itself is the same.

 

[2door]

The heat range numbers are clear, but it seems that the Chinese are not following that convention.
This chart shows both types on the same line, as if they are the same:
Spark Plugs|spark plug|K6TC|A7TC|F5TC|E6TC|D8TC|Z4C


In response to 2Door's comments, I think that it is a stretch to even call them a spark plug wire or or ignition cable. To me, they look more like a plastic tube or hose with a couple strands of copper wire shoved thru 'em. Although I never tried it, I think a piece of brake cable housing (with a steel inner lining) would work better that what is supplied with the kit, plus it already has a hole in the center, ready to accept the CDI screw.

Then by all means I think you should use brake cable. Go for it. Even that will be better than resistance wire. At least there's a metal conductor in there somewhere.
Tom