Anyone use Champion C59YC spark plugs

[My427stang]

As far as I can tell, the C59YC is significantly colder than a 3924 or RC12YC.

Trying to help diagnose someone's EFI install and beginning to think these plugs are too cold for normal street use without an MSD.  Best I can figure out is that they are equiv to a 3910 Autolite or RC4YC Champion but I haven't found a good chart that compares race plugs to normal numbering

Anyone have experience with them?

[fe66comet]

I have never had good luck with race plugs on an ignition of any type on the street. They work good for a very short time and wear quickly, also as you suspected ignition voltage is also realitive. I have used stock plugs with even the hottest ignitions with no erosion. I do however buy the 6-7 dollar platinum plugs.

[Ford428CJ]

Ross, Those plugs cross over to a NGK R7435-9 plug. That is a very cold plug. That is the coldest plug that they make, a -9....

http://www.sparkplug-crossreference.com/convert/CHAMP_PN/C59YC

[My427stang]

I ended up sticking a 3924 in the SBF, cleaned up good as new.  FWIW those were the specified plugs from the engine builder for a street 331, silly.