Hello Everyone,

I just joined this forum and wanted to find out if anyone knew which plug is best for the 454 mercruiser 7.4 with rochester carb and after market mainifolds on a 1990 27 foot switzer race boat. I bought the ac delco r43t and the boat ran hard. Was interested to know if any one knew if i should run the NGK Br6fs plug and would it be the better choice.

thanks,

NGK BR6FS stock #4323 !!!!!!!!!!!!! 2 bucks a piece .

I have used them all. Right now I use the AC Rapid Fire. A little more money.

Using the NGK BR6FS right now without issue, but did not have any issue with the MR43T either. Just changed cause someone suggested.

I thank all you guys on the recommendations, it's great to know. I tried the ac delco iridium but they were horrible and the engine flooded and my plugs were burnt and shot up. Ac r43t are working like a charm and wanted to know if the NGK's or the rapid fire #1 were any better. Did not want to have the same issue I had with the iridium ac plugs. It was scary especially being at hell's gate by the east river.

Thanks again.