Cross-Reference
Champion RCJ6Y vs RCJ7Y: Heat Range Difference Explained
Updated 2026-10-16
Champion RCJ6Y and RCJ7Y share the same thread, reach, and resistor design. RCJ7Y is one step hotter. See which equipment specifies each and the NGK equivalent.
What is the difference between RCJ6Y and RCJ7Y?
Heat range only. Champion's code guide says a higher number means a hotter plug, so RCJ7Y runs one step hotter than RCJ6Y. Thread, reach, resistor design, and projected nose are the same. Use the plug your equipment manual names: Stihl MS and FS models in our records list RCJ6Y, while Husqvarna 120 and 435 to 460 saws list RCJ7Y.
Read the manufacturer referencesDirect Comparison
| Check | Champion RCJ6Y | Champion RCJ7Y | What decides fitment |
|---|---|---|---|
| Heat range | 6: one step colder | 7: one step hotter | Champion's higher number is hotter. Use the heat range your manual names. |
| Thread and reach | 14 mm x 1.25 mm, 0.375 in reach | 14 mm x 1.25 mm, 0.375 in reach | Same shell; both thread into the same cylinder. |
| Resistor and nose | R resistor, Y projected nose | R resistor, Y projected nose | No difference. |
| NGK equivalent | BPMR7A (4626) | BPMR7A (4626) | NGK lists the same plug for both. |
| Typical equipment in our records | Stihl MS 170, MS 180, MS 250, FS 38, FS 45 | Husqvarna 120, 435 to 460; Poulan Pro P3314 to PP4620AV | The equipment manual decides; the model page shows the source. |
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What Heat Range Changes
Heat range describes how quickly the plug tip sheds heat into the cylinder head. A hotter plug keeps its tip warmer, which helps burn off fouling in an engine that runs rich or idles a lot. A colder plug suits an engine that runs hot under load.
One step is a small difference. It still matters, so start with the plug your manual names rather than whichever one is on the shelf.
Can I Use One in Place of the Other?
NGK treats them as one application, since its catalog lists BPMR7A for both. Some equipment manuals list only one Champion number, and that is the safest choice.
If you substitute, read the old plug after a few tanks. Dry black soot points to a plug running too cold; a white or blistered insulator points to one running too hot.
Primary Sources
- Champion spark plug code guideStates that a higher Champion heat-range number is a hotter plug, and defines the R, J, and Y codes.
- NGK spark plug cross-reference catalogLists both RCJ6Y and RCJ7Y against NGK BPMR7A, stock number 4626.
- Husqvarna 120 Mark II operator manualAn example of a manual that names RCJ7Y specifically.