Mercruiser 1998 5.7 EFI engine what spark plugs to use

[jws123]

I have a Mercruiser 1998 5.7 EFI 2barrel non vortec what spark plugs do i use? i went to boat store but their book sucked i need to know what NGK plugs to use the plugs that came with my boat where some **** car acdelco plugs someone put in there most likely the wrong ones. The book for my boat says nothing about plugs.

 

[Bondo]

I have a Mercruiser 1998 5.7 EFI 2barrel non vortec what spark plugs do i use?

Ayuh,.... A '98 sure oughta have Vortec heads, unless it's not original,....

'n Which AC Delco plugs,..?? MR43LTS are Vortec plugs, 'n MR43T are pre-vortec plugs,....

 

[MBAKER]

Assuming 8 bolt Vortec intake pattern....

NGK BPR6EFS ...... I have also run TR6 only difference is the V groove electrode.

ACDelco MR43LTS

 

[jws123]

Intake has 12 bolts could not be original just got the bat been sitting for 6 years been trying to get it to run right all summer

 

[khe]

A Chevrolet engine will use AC Delco plugs from the factory. Bondo listed the correct plugs.

 

[thumpar]

Vortec came around in 1996 and in full use by 1997. Ac plugs would be factory for vortec or non.

 

[Bt Doctur]

there should be a small metal tag just above the starter with a serial number

 

[MBAKER]

surprised it has a 12 bolt intake, but none the less if that's the case you should use the Delco MR43T or the equivalent NGK is BR6FS. Either one will work fine. NGK actually makes several plugs for ACD anyway.

The critical thing here is the plug length, the Vortec head uses a longer plug. If you stick a short plug in the vortec head performance suffers but it runs. If you stick a long plug in the older non vortec head you likely hit the pistons or a valve