Spark plug hex size

[38racing]

Just watched a video where guy used a 5/8 hex where original was 13/16. Led me to realize some plugs that cross over except for being different hex. Looks like f6rtc and k6rtc are same except for hex size . Does hex size really matter except for when 13/16 might prevent socket excess ?

[RoyM]

I hate those skinny plugs on the Chinesium engines, the threads strip too easily. Maybe the small plugs dissipate heat faster but I was a mechanic not an engineer so wadoo I know.

[KE4AVB]

That is the only difference when it comes to the NGK plugs that I see. More of a clearance issue than anything else. That is why I switching over to stock the NGK BK series primary

[38racing]

I hate those skinny plugs on the Chinesium engines, the threads strip too easily. Maybe the small plugs dissipate heat faster but I was a mechanic not an engineer so wadoo I know.

Threads are same. 14 mm. Just hex is different. I use bkr5e in place of rc12yc. Looks like bcpr6es is also a cross. Which leads me to think I could use any of these 5/8 hex to replace. 13/16 bpr6es which I use to replace f6rtc. I've been ordering both from rockauto but had issues getting both from same warehouse.

[KE4AVB]

Actually the BCPR5ES is the cross for the BKR5ES. Both supersedes to NGK-2460 stock number. The BCPR6ES supersedes to NGK-2330 stock number.


My cross reference guide has the following two Champion RC plugs crossing to the K6RTC.

RC10YC4 K6RTC-11
RC9YC4 K6RTC-11

And the F6RTC is crossing as follows in the Champion RN plugs.

RN10Y F6RTC
RN10YC F6RTC
RN9Y F6RTC
RN9YC F6RTC
RN9YCC F6RTC

Reference>The CHAMPION -TORCH Cross Reference chart in the Briggs advance service info directory.
Reference>NGK Spark plug code en in the Briggs advance service info directory.

[38racing]

Interesting about that f6rtc to champion. The video guy I think had a f6rtc in his hand and said he was replacing with smaller hex briggs 491055. When I crossed that briggs I found the rc12yc which doesn't appear to be the correct champion fot that f6rtc.

[KE4AVB]

Interesting about that f6rtc to champion. The video guy I think had a f6rtc in his hand and said he was replacing with smaller hex briggs 491055. When I crossed that briggs I found the rc12yc which doesn't appear to be the correct champion fot that f6rtc.

The RC12YC is a hotter plug than the F6RTC if the cross chart I have is correct. But you risk pre ingition if the plug tip temp is too high.

[38racing]

Your chart confirms my thought the video guy should not be putting in the briggs that crosses to rc12yc

[KE4AVB]

I think I got things straight now. According to Torch Spark Plug catalog I just downloaded the Torch uses the same heat range number system. so the f6rtc would the NGK with the 6 heat range.

I will upload that catalog to the Briggs Advance directory so you can download a copy for reference. It is titled "Torch Spark Plug Catalog". It will help to completely decode the Torch SKU number.

Soon or later I get the right info posted. I do try my best to have accurate info posted as I also depend on it myself. This was a little confusing on this end too.

[KE4AVB]

Well made a slight change to the Briggs directory by adding a Spark Plug sub-directory where I place all the catalogs and other info about spark plugs I have.