ok i bought some iridium spark plugs.. R19 and R20.. which ones go on top and which ones go on the bottom... like which ones are the above ones and which ones are the lower ones..??

 

2 of you plugs should be marked with a "T" and the other 2 should be marked with an "L". The "T" plugs go in the top holes and the "L" plugs go in the bottom holes. Take care not to confuse your spark plug wires, its easy to do and your car will run like **** or not at all if you get them crossed.

 

R19 and R20??? what plugs are those??? Sure you are not missing some numbers there???

And

Top= trailing
Lower= leading

 

Probably Denso iridiums.

 

ok so i checked autozone where i got the plugs and it says that the R20 are on the bottom( leading side). and the r19 top( trailing side) thats what it says. but you guys say leading is on top? so do i put the r20 spark plugs on the bottom or the top?!? help.. confused

 

The correct denso Iridium plugs would be the IRE01-27 and the IRE01-31. The 27 would be the leading plug and the 31 would be the trailing.

So again what plugs are these? Denso? NGK? HKS??? What plugs are these?

 

They are Densos.
http://www.globaldenso.com/PLUG/racing/spec.html
Scroll about halfway down the page and look at the no.
IRE01-31 = R20
IRE01-27 = R19

 

The spark plugs closest to the oilpan are the leading plugs. The upper plugs are the trailing plugs. It's marked on the rotor housings.

 

yeah, Trailing = Top Leading = Lower

I can't believe you missed that Mark.

 

Not sure what you are saying since I posted that last night in this thread.

Maybe you didn't read the thread as I posted that in the 3rd reply in it.

 

Whoops, sorry mate no disrespect.. I was quite tired and all I saw was the OP says the the top was leading and you posted after him not informing him of his mistake.. so I was informing him.. and just mentioning how I couldn't believe you didn't correct him.. But you mentioned it before, a few posts before he said that. I guess I overlooked your first post. Sorry, no harm right?

 

I don't see any misinformation in this thread. Yeti, try sleeping for a while, then come back.

 

iridium???

NGK all the way!

 

i know this is an old thread, but thanks Mark for distinuishing between which ones are leading and trailing. I know the difference but I didnt know whether the 27s or the 31 were what.