Finding the Champion Spark Plug CJ8 sold out, I was informed by the mower repair shop that the Champion CJ8Y was an acceptable replacement. I purchased it, but after researching I'm inclined to believe it should NOT be used to replace the CJ8. Before returning it, can someone assure me one way or the other? Thanks! Larry
Is Champion Spark Plug CJ8Y an acceptable replacemet for CJ8?
- Thread starter hugh37
- Start date
Details about Champion CJ8Y:
Threaddiameter: 14mm
Threadreach: 9.5mm
Seattype: flat
Hexsize: 19mm
Tipconfiguration: projected
Construction: Standard construction
Terminaltype: Solid
Details about Champion CJ8:
Threaddiameter: 14mm
Threadreach: 9.5mm
Seattype: flat
Hexsize: 19mm
Tipconfiguration: non projected
Construction: Standard construction
Terminaltype: Removable
i think they should interchange.
Threaddiameter: 14mm
Threadreach: 9.5mm
Seattype: flat
Hexsize: 19mm
Tipconfiguration: projected
Construction: Standard construction
Terminaltype: Solid
Details about Champion CJ8:
Threaddiameter: 14mm
Threadreach: 9.5mm
Seattype: flat
Hexsize: 19mm
Tipconfiguration: non projected
Construction: Standard construction
Terminaltype: Removable
i think they should interchange.
bertsmobile1
Lawn Royalty
Put a dollop of plasticine about .040" on the outside of the ground electrode.
Screw the plug in but leave the mower turned off.
Crank it as fast as you can
Remove the plug & check that the plasticine has not been flattened.
The projected nose electrodes poke further onto the cylinder so it can foul on the cylinder ( OHV & 2 stroke engines ) or valve ( SV engine ).
FWIW I an yet to find an engine where a projected electrode plug can not be used & I use them whenever possible because they burn better
Screw the plug in but leave the mower turned off.
Crank it as fast as you can
Remove the plug & check that the plasticine has not been flattened.
The projected nose electrodes poke further onto the cylinder so it can foul on the cylinder ( OHV & 2 stroke engines ) or valve ( SV engine ).
FWIW I an yet to find an engine where a projected electrode plug can not be used & I use them whenever possible because they burn better
Tinkerer200
Well-Known Member
I think you will find the "Y" is an extended plug, check that and do not use if that is the case.
Walt Conner
Walt Conner
bertsmobile1
Lawn Royalty
yes it is Walt, hence the plasticine test.
Since it was so covenient to return the CJ8Y plug I chose to do just that, rather than risk any problem. Sure appreciate all the good responses! While it seems agreed that the "Y" designates an extended thread, I'm curious why it's so seemingly difficult to find answers without having to resort to a forum, which is great, but more time consuming?? Larry
bertsmobile1
Lawn Royalty
Not hard at all
search Champion spark plug naming system.
or
go to Champion's web page, it is all there.
It is just a little confusing if you don't play with plugs every day of the week
CJ8 is the standard plug
C = short plug
J = 14mm x 3/8" thread with a 13/16 hex
8 = heat range
CJ8Y is the standard plug with a longer electrode
RCJ8 is the standard plug with a higher resistance
RCJ8Y is the standard plug with a higher resistance and a longer electrode.
Then there is a 3 ,4 or 5 digit number on the box.
That is a use number so I can buy them with 3 different gap distances so I don't have to set the gap before fitting.
If I was a car maker and ordered 1,000,000 of them I would get my own number if I wanted them set to a different gap.
Champion make around 4,000 different spark plugs
search Champion spark plug naming system.
or
go to Champion's web page, it is all there.
It is just a little confusing if you don't play with plugs every day of the week
CJ8 is the standard plug
C = short plug
J = 14mm x 3/8" thread with a 13/16 hex
8 = heat range
CJ8Y is the standard plug with a longer electrode
RCJ8 is the standard plug with a higher resistance
RCJ8Y is the standard plug with a higher resistance and a longer electrode.
Then there is a 3 ,4 or 5 digit number on the box.
That is a use number so I can buy them with 3 different gap distances so I don't have to set the gap before fitting.
If I was a car maker and ordered 1,000,000 of them I would get my own number if I wanted them set to a different gap.
Champion make around 4,000 different spark plugs
Thank you for the research that others have avoided or refused. MANY here (most) confuse "thread reach" with the height of plug (long reach vs. normal). To avoid piston damage (etc...). make sure to match the thread reach. If you want or need your plug to be 'taller' or 'shorter' (how much room you want to give to the high tension lead and cap). choose a longer or shorter electrode (which basically includes the entire length of the plug from lead connection to the tip at the spark).
and will you please explain "with a higher resistance" to the masses. ? HINT: has to do with a resistor manufactured to reduce RF in adjacent areas (think AM radio, etc..._)