1997 4.3 Correct Spark Plug?

[StevNimrod]

Helping a neighbor with his 1997 with twin Mercruiser 4.3s. His serial numbers are:

OK1993530
OK1993531

Pulled the plugs last night and out came Champion RV8C (shorter plug).

I double checked the FSM while he consulted his Seloc (which I recommended he keep in the bathroom).

The FSM indicated the Champion equivalent of RS12YC (longer plug). The Seloc indicated RV8C. The parts catalog is showing me Mercruiser 33-816336Q, which I believe crosses to the AC MR43LTS and is the equivalent of the RS12YC.

I was confident in the Merc information, but to check we brought the engine up to TDC and shoved a pen in the #1 plug hole. Took quite a bit of pen before hitting the piston so we were confident the longer plug wouldn't be a problem.

But...the owner asked that I get another opinion here since there's no real downside and just in case there's something we're missing...that the pen didn't tell us.

 

[Don S]

Re: 1997 4.3 Correct Spark Plug?

Your serial numbers are too long by 1 number

All the 0Kxxxxxx numbers use the same plug NGK BPR6EFS or AC MR43LTS. Do not use champions.

 

[StevNimrod]

Re: 1997 4.3 Correct Spark Plug?

Thanks Don!

I'll be sure to double check those serial #s so he has the right information on file.

I told him last night that I heard about some troubles with Champion plugs (I run the same model - but AC Delco - plug in my engine) and he decided to go with your recommendation.