Spark plug for 502 bbc crate

Need help, Can't find the set of plugs that were in the motor. ( 502 bbc crate )
This motor is was built in 98, it has 14 degrees of base timing.
This is the gm plug is # 25164642.
I be live it is the GM #4 plug. I was using Champion Plugs

Is there a conversion chart on the web anywhere?
Thanks Bob

 

just about any of your parts stores should be able to tell you what plugs interchange with your number...... I'll call one and see.... AC #4 rapidfire, auotlight 63 ,champion 63 this is according to Advance Auto Parts hope this helps

 

In the parts spec book that came with my 502 GM calls for a Rapid Fire #4. I use an AC R44XLS. GM calls for a pretty cold plug for this street motor. The R44XLS is 1 heat range hotter, works good for me.

 

Just don't use Champion Plugs.....

 

Thanks Marty

 

Did shearch on line, And I hit the mother load on spark plug converson charts 34 pages

http://www.angelfire.com/extreme4/skidoolympique/SPARK_PLUG_CROSS_REFERENCE.htm

 

Autolite racing AR3934 works for me, can go colder (3933 or 3932) in really hot weather.