LITAMG

Hey guys, I've got a 2005 CLK55 AMG and I'm looking to buy spark plugs but I'm seeing some major differences based on where I look to get the spark plugs. My owners manual says NGK 3588 ILFR6A Laser Iridium Plug which has 26.5mm (1.04") long threads AKA Reach. FCP Euro, NGK, oreillyauto and all the other websites say it takes NGK 5344 IFR6D10 which has 19mm (3/4") Reach. A fourth of an inch is a big difference and could ruin your engine so I'm sceptical to use what the owners manual says to use. On the other hand, I am wondering if I would be sacrificing power and efficiency by using a shorter spark plug that would act almost as a spark plug fouler since it might be recessed in the spark plug opening. Has anyone used the ILFR6A one or have any insight? I have searched the forums and read way too many threads and found no solid answers. Any help would be greatly appreciated!

IFR6D10

ILFR6A


https://www.ngk.com/product.aspx?zpid=9791
https://www.ngk.com/product.aspx?zpid=9806

cindyclk

I don't have your car but would go with the owners manual plug....what's in the engine right now?

LITAMG

The engine currently has the NGK 5344 IFR6D10 which has 19mm (3/4") Reach. I just got a response from a reputable tech and he said the following:
"The only difference in plug reach I'm aware of is M113K vs M113. The Supercharged engine has lower Compression Ratio, dished pistons, and a longer reach plug. Welcome to poor cross-referencing. I have always used the NGK 5344’s"
So I am going to take their advice and stick with the NGK 5344 haha