I have a 1950 flathead 6-cylinder F1, and and trying to determine the correct spark plug to use. The plug I pulled out has an extended electrode (ChampionRH18Y), but the plug I was told to use was one without an extended electrode (Champion RH10C). Need help determining what is correct...advice?

 

I have been using the RH10C for about 50 years
Ed
near Philadelphia

 

well thanks, Ed for that info. I think 50 years of usage is confirmation enough for me!

 

If you want to be a stickler for originality, the 48-52 factory shop manual lists the correct spark plug for all engines as part number 01T-12405, Type H-9, gap .028-.032. Coincidentally on ebay right now, there's this set of NOS Champion H-9's, strictly for your viewing pleasure. I am not endorsing your purchase of said plugs.

https://www.ebay.com/itm/Champion-Sp...-/182378586616

 

I've had much better luck in my V8 with Autolite 216's, Champions tend to foul easily. The 6 uses the same plugs.

 

^^^ +What Ross said.

 

 

Yes, that indeed would be rust. Obviously not been kept in a climate-controlled atmosphere for the last 60 years.

 

My manual says .025 - .028 on the plug gaps?

 

thanks for the additional info, folks!

 

It appears both are correct. Remembering the charts are in the back of the book, I looked at the first one I came to, not realizing it was the 1952 supplement section. The last page, page 95, shows the 025-032 spec. Your spec is in the original section, page 379. Both say it is for all engines, so apparently Ford engineers felt that the wider gap could work. Beyond that, I know nothing.