BUP

iTrader: (9)

and the mag 454 MPI for 1998 different than the 1998 454 MPI and both are GEN VI

MerCruiser 454 Mag MPI Bravo (Gen. VI) GM 454 V-8 1998 Distributor & Ignition Components Parts

ezstriper

I know some if not all gen VI big blocks using oval port heads use a long reach plug vs the old short MR43's

getrdunn

iTrader: (7)

So in reality no one knows for sure what year engine, model etc he is referring to. I get the avitar show 98 crowine but...
His question was the difference btwn the two plugs stated and his manual stated mr43t. Is it a generic manual or is it possible he doesn't have original engine? Just saying! �� We do know it's a 454 carbed engine just not a 100% certain on year. I've had a boat with 3 different gens and size engines so it would be like going to Napa looking for plugs for a 76 escort although you have a modified 302 crammed in it. You'd likely leave with 4 incorrect plugs.

BUP

iTrader: (9)

just putting this out there Merc did not make any carb engines for big blocks in 1998 nor in 1997 - their last carb big block was 1996 - 454 and no 502 carb engines for 1996. info is for black production side.


1997 454 was TBI and MPI
1998 454 was MPI and I believe last of the TBI s

BUP

iTrader: (9)

the L 29 / 454 used the long reach plugs

getrdunn

iTrader: (7)

It's good info bup. The simple days are gone. Honestly I like all the pre early ninety merc stuff. Probably cause it's what I worked on the most and could do most anything with a blindfold if I had to. Maybe a quick peek for timing. Lol... I get it though things change for better or worse.

ezstriper

keep in mind you have to account for replacement long block engines, where mine got screwed up, no plug #'s came with engine, so what we had been using is what we used, wrong for about 4 years, until pulled one engine down saw the plugs were way short...but seemed to run fine, but never saw over 4000 either

getrdunn

iTrader: (7)

4 years.... at least they don't owe you anything.

spaniard

I just went this route today, but wasn't sure about the gap size(went with NGK's BR6FS plugs). I went onto NGK's website, but their gap recommendation is set at .032, but set them at 35. I keep reading 40, but for the MR43TS.
How much of a big deal will it make, .040 vs .035?

MR43TS are available here, but as someone posted a link, they also cross reference to NGK BR6FS(which is why I went with NGK. Can anyone cite references on the correct gap?

Thanks

BUP

iTrader: (9)

Your engine serial number is ??? Thats the way all parts and procedures goes by for the marine end. regardless what year the hull is.

I have the latest NGK app guides as well for all powersports. NGK has not had a new guide out in about 3 or 4 years. The new guide came out past couple of months.