Have bought a set of plugs for a 92 Honda Civic 1.5 Lsi.According to the haynes manual they should be Champion RC9YCC4, which I have in at present.
According to the supplying motor factors they should be RC8YCC4 which is what their Champion application chart states it to be.The plugs look the same from the washer down but above the washer they are different. One has more metal above the washer than the other.What is the difference between them and should I fit them ?.
As they are both RC(X)YCC4, then the plugs are dimensionally similar, with the same copper electrodes. So, they will fit without problems. The change from 9 to 8 means the new plugs are slightly 'colder'- they conduct heat away faster.
Now, the Haynes manual may be out of date, the spec for your car might have changed, or the Champion list may be wrong, or appply to a later model. Always a problem, as I suspect the car's own manual lists japanese plugs, and getting exact comparisons with other makes can cause problems. Check if the Champion list is up to date, and also ask if they've got a spark plug comparison chart and check the Champion equivalent to the OE plugs listed in the car's manual.
According to the latest Unipart parts information catalogue (where I work) the plug specified for your car is GSP 2114 which is the same as RC9YCC4. This is also confirmed in the NGK and Champion reference books. Take the plugs back to the factor and get them changed for the right ones.
I would ignore what Haynes says and stick to the plugs as recommended by your engine maker,even though they maybe more costly.If they recommend them then you will be OK.
Whilst Champion spark plugs are good, they are not suitable for all cars.
