Mercruiser 5.7L - Spark Plugs confusion

Rutto

Seaman Apprentice
Joined
Sep 1, 2011
Messages
33
Dears,
I have big confusion with spark plugs for my engine 5.7L carb number OC602940.

Recently replaced with another long block (inl. heads), I was troubleshooting some problems with it and I decided to replace the spark plugs, I went to a shop and they missed the NGK BR6FS I had on it.
I took my phone and made a quick search for mercruiser 5.7 and found out this code: NGK BPR6EFS so I bought 8 of this.

I was surprised when I saw how different those BPR6EFS were by the BR6FS... BPR6EFS the long reach plug how can they be both ok for the same engine ? Am I going to make big damages to my motor if I use the BPR6EFS ?

Thank you !
 

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
Re: Mercruiser 5.7L - Spark Plugs confusion

Use BR6FS. Good catch.
 

Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
Re: Mercruiser 5.7L - Spark Plugs confusion

To answer your question of damaging the engine,
You can use a short plug in a long reach head, but not the other way around. The plug will probably hit the piston. A short reach will just not get far enough into the chamber and you will loose a bit of power.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Mercruiser 5.7L - Spark Plugs confusion

.... how can they be both ok for the same engine ? ....

They're not. The BR6FS is for non-votec heads, the BPR6EFS is for votec heads.

Chris....
 

Rutto

Seaman Apprentice
Joined
Sep 1, 2011
Messages
33
Re: Mercruiser 5.7L - Spark Plugs confusion

They're not. The BR6FS is for non-votec heads, the BPR6EFS is for votec heads.

Chris....

As I replaced the long block, including heads, how can I know if the new heads are vortec or non-vortec ?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser 5.7L - Spark Plugs confusion

Measure the threads in the head, or just look at them. Are they short or long like the plugs.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Mercruiser 5.7L - Spark Plugs confusion

As I replaced the long block, including heads, how can I know if the new heads are vortec or non-vortec ?

How many bolts holding the intake to the heads? 12 is non-vortec, 8 is vortec...
Also the Vortec bolts are vertical, non-vortec bolts are at an angle (more vertical to the heads surface)
 
Top