Need help with plugs selection

[ColonelNivlag]

Hi all,

Need to replace plugs on my boat. See my previous thread here where you kind folks help me identify the motor.

On removing the old plugs I'm running BR6FS but from what was said in this thread I think I should be running MR43LTS and not the short reach plugs.

The boat has always been hard starting. I'm wondering if this may be the cause. Mind, the plugs were absolutely knackered though & I'm going to do the leads too.

So, do I play it safe and just put back in what I took out or go the non-short version.

Any help appreciated.

 

[Scott Danforth]

your plugs are based on the cylinder heads.

what cylinder heads does your motor have? vortec heads require longer reach plugs

 

[ColonelNivlag]

your plugs are based on the cylinder heads.

what cylinder heads does your motor have? vortec heads require longer reach plugs

Hi Scott,

In the thread I linked to, the forum helped me identify it as a Vortec block running old accessories.

Does this mean it's Vortec heads too? Take it you can't run non-vortec heads on a vortec block?

Boat did run fine with the BR6FS installed, just hard to start.

 

[Bondo]

Ayuh,..... The blocks don't care,..... In that thread, it's thought you have a Vortec motor,.....
Count the intake bolts to know for sure,.... 8 bolts is Vortec, 12 bolts is pre-vortec,.....
Vortec heads use the longer plugs, pre-vortec use the shorter plugs,....

 

[Scott06]

Hi Scott,

In the thread I linked to, the forum helped me identify it as a Vortec block running old accessories.

Does this mean it's Vortec heads too? Take it you can't run non-vortec heads on a vortec block?

Boat did run fine with the BR6FS installed, just hard to start.

It looks like in your other thread you have an 8 bolt intake with 8 vertical intake to head bolts. If that is the case use MR43 LTS.

As bondo mentions Vortec is the head type not the block. Given the interchange of parts over the last 68 years on the SBC you can have a lot of mix and match of parts ...

 

[ColonelNivlag]

It looks like in your other thread you have an 8 bolt intake with 8 vertical intake to head bolts. If that is the case use MR43 LTS.

As bondo mentions Vortec is the head type not the block. Given the interchange of parts over the last 68 years on the SBC you can have a lot of mix and match of parts ...

Thanks, will confirm tomorrow. 8 or 12 bolts.

 

[ColonelNivlag]

It looks like in your other thread you have an 8 bolt intake with 8 vertical intake to head bolts. If that is the case use MR43 LTS.

As bondo mentions Vortec is the head type not the block. Given the interchange of parts over the last 68 years on the SBC you can have a lot of mix and match of parts ...

I see 8 bolts... So I'm running the wrong plugs then and need the MR43 LTS?

 

[Scott06]

I see 8 bolts... So I'm running the wrong plugs then and need the MR43 LTS?

Yeah That's a vortec so you will need MR43LTS or equivalent

 

[Bondo]

I see 8 bolts... So I'm running the wrong plugs then and need the MR43 LTS?

Ayuh,..... Correct,.....

 

[Jgcrock99]

Yeah That's a vortec so you will need MR43LTS or equivalent

Sorry to piggyback here but I have a similar question. My boat is a 95 Chaparral 1930 sst with the 4.3lx mercruiser with the thunderbolt system. Head covers say vortec but I will look at the bolt count. Is there any reason I wouldn't be able to run the platinum or iridium performance type plugs listed for the auto equivalent vs marine? This is the same block they used in the 90s model gmc/chevy light trucks. I am running the br6fs plugs as well but do the plugs have to be marine? I know certain things need to be marine but I don't understand why the plugs would need to be. Those performance plugs handle heat and corrosion better so if I'm running 3-4k rpm or idling for long periods it seems like a better choice. Thank you.

 

[Scott06]

Sorry to piggyback here but I have a similar question. My boat is a 95 Chaparral 1930 sst with the 4.3lx mercruiser with the thunderbolt system. Head covers say vortec but I will look at the bolt count. Is there any reason I wouldn't be able to run the platinum or iridium performance type plugs listed for the auto equivalent vs marine? This is the same block they used in the 90s model gmc/chevy light trucks. I am running the br6fs plugs as well but do the plugs have to be marine? I know certain things need to be marine but I don't understand why the plugs would need to be. Those performance plugs handle heat and corrosion better so if I'm running 3-4k rpm or idling for long periods it seems like a better choice. Thank you.

You would get best results by starting your own thread. There were some early 4.3 s made with valve covers that say vortec but that do not have what later became known as vortec heads as the name bortec was used for many gm engines and a better cylinder head design 96 and up.

not sure what is different about marine plugs except maybe the heat range. I think putting a platinum or iridium plug in that engine is probably just a waste of money. The platinum and iridium are for long change intervals not seen in boats. you will be fine with the mr43 s it came with

 

[Scott Danforth]

Marine plugs have nickel plating

 

[Bondo]

Marine plugs have nickel plating

Ayuh,...... 'n the AC Delcos actually have a nickel alloy body, rather than carbon steel,....
Extremely rust resistant,......

 

[nola mike]

Ayuh,...... 'n the AC Delcos actually have a nickel alloy body, rather than carbon steel,....
Extremely rust resistant,......

I've been using these since my ngks rusted to crap after one season and one broke trying to remove. Any theoretical/magical performance gains offset by being able to remove the damn things.

 

[Bondo]

I've been using these since my ngks rusted to crap after one season and one broke trying to remove. Any theoretical/magical performance gains offset by being able to remove the damn things.

Ayuh,..... So long as a spark plug, Sparks,...... What more would you want,..??