BIGJOHNG2 1 #1 Posted February 8, 2022 (edited) I see that there are three spark plugs listed for O&R engines... Champion UY-6, CJ-8, and CJ-14. Is there one that works better than others? It seems like the UY-6 is harder to find. Any thoughts? John Edited February 10, 2022 by BIGJOHNG2 correct typo Share this post Link to post Share on other sites
Wallfish 698 #2 Posted February 10, 2022 UY-6 are the older 10mm plugs but there are cross references to other manufacturer's plugs. Same for the others Overwhelming majority of mine still have the original Champion plugs in them and fire fine. Share this post Link to post Share on other sites
factory 487 #3 Posted February 15, 2022 There is no choice but to use the UY-6 (10mm) in older engines, unless the cylinder is replaced with the 14mm type used on all later engines. As for the CJ-8 & CJ-14 (both 14mm), they were both still listed in the 1971 master parts price list, but O&R did recommended to use the CJ-8 for chainsaw engines in a service bulletin. Note, some of the modern Champion spark plugs have a none removable solid top for the plug cap. Earlier coils require the type with a threaded top for the plug lead, unfortunately this means searching for old stock, some sellers use generic pictures so best to ask to confirm what they are selling. David Share this post Link to post Share on other sites
Wallfish 698 #4 Posted February 17, 2022 On 2/15/2022 at 4:58 PM, factory said: There is no choice but to use the UY-6 (10mm) in older engines I have some old Autolite P-6 10 mm plugs bought when I first started collecting Share this post Link to post Share on other sites
