Plugs different to the manual?

Joined
Jul 7, 2009
Messages
13
Hi, just wondering what everyone else is running in theirs, the engine is a 3.0 Mercruiser, my mate has just checked the plugs on the actual engine and they are:

ac-mr43t plugs, which are BR6FS for NGK

I have just downloaded the manual for the GM 4 cylnder engine, and it says that they are:

AC-MR43LTS plugs, which are BPR6EFS for NGK

I seem to have read somewhere that the BPR6EFS plugs are for the 3.0 LX model with a slightly different cylnder head and need a shorter plug.

I guess I should go for what is printed on the engine/what my mate has given me, can anyone confirm this for me?
 

Dryon

Petty Officer 3rd Class
Joined
Jul 31, 2007
Messages
86
Re: Plugs different to the manual?

There is a mercury Service Bulletin that addresses recommended spark plugs, but it is only for engine serial #'s 0M300000 & above. Need your serial # to know if it applies.
 

Bondo

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70,510
Re: Plugs different to the manual?

the engine is a 3.0 Mercruiser

Ayuh,.... What Vintage,..??

The AC Delco MR43T is used for All but the Very Latest,+ the Very Oldest of the 3.0l motors...

The AC MR43LTS is for the Vortec headed motors...
They may contact the pistons if used in the Pre-Vortec motors....
 
Joined
Jul 7, 2009
Messages
13
Re: Plugs different to the manual?

Ayuh,.... What Vintage,..??

The AC Delco MR43T is used for All but the Very Latest,+ the Very Oldest of the 3.0l motors...

The AC MR43LTS is for the Vortec headed motors...
They may contact the pistons if used in the Pre-Vortec motors....

This is why im asking lol its an old old engine, probably about 20 years old or so lol so im guessing its a pre-vortec?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Plugs different to the manual?

Either the AC-MR43T or NGK BR6FS will work fine.
 
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