502 carbed spark plugs
 

I need some help please! I just purchased a used 97 baja boss with a built 502. Im going to do a tune up here soon and want to know what spark plugs are best for this application. It is a performance built engine close to the 500HP(?) specs, around 500 hp and 575 lbs-ft and has a carb. The plugs that are in it are Champion RV15YC4 and look to have worn normally. Any one with a carbed 502 out there have any suggestions? that would be great. thanks Derrick

Not sure with your application, but i've had real good luck with Bosch Platinums in mostly stock engines.I use them in everything i own.
Found a conversion chart that list all brands if you need it.

AC Rapid Fire #1's worked very well for me.

They get my vote to.

Re: 502 carbed spark plugs
 

do you still have chart?

Re: 502 carbed spark plugs
 

A MR43T is a very popular marine plug. I too run the platinums in my street vehicle, but I havn't been able to cross reference to a marine plug. The MR's have a stainless body so they won't corrode.

Re: 502 carbed spark plugs
 

DENNIS IF THE ENGINE HAS GM IRON HEADS OR EVEN MERLINS WHAT I USE HERE AT THE SHOP ARE NGK YR5 THIS IS THE PLUG I USE EXCLUSIVELY AND WE BUILD ABOUT 2 ON A MONTHLY BASES WITH NEVER A PROBLEM WITH THAT PLUG. HOPE THAT HELPS LAZ MESA WWW.MESABALANCING.COM,

Re: 502 carbed spark plugs
 

Those Champion plugs will work just fine. They have an extended tip so they will not foul easily if you do a lot of idling. I have them in my 502 and they work great. I doubt if a more expensive plug will make any difference in how it runs.

Re: 502 carbed spark plugs
 

What about plugs for aluminum heads.I have to use the ones with the small hex or I can't get a plug wrench on them.Even with the small hex I had to make a custom machined down socket with a universal tig welded to it.I have used champion rc12yc an ac fr3ls.I like to change my plugs a couple times a season just to monitor whats happening in the engine.I have not had any real complaints with either plug.I would like to try a colder one because after a hard run I sometimes get a bit of run on at shutdown.

1990 baja 250
 

just curious what spark plugs i should be running in stock 502 jasper motor in my Baja? right now i have NGK R (BR6FS) plugs. Had dads friend who is mechanically inclined that he doesn't think they are right, it thinks i should be running NGKUR4? any input on what i should be using?