My 38 scarab kv has orig old school Merc 370 I’ve never bothered to learn the intricate details.
what were the difference between this and the 420 trs (?) I think came with.

also if I repower what would be the recommendations. For power with my highest priority being reliability.

the 370 and the 420 were the HP levels of the motors....don't think there was anything other than that. At least that's what i have come to believe....i had a 370 TRS baja that was a basket case and stripped it down for parts....found another boat that had a 420 pkg and all i could see was the motor being different.

believe the main difference was cam, intake and carb and exhaust.

Reliability being subjective - 200 hrs before refreshing the heads is good !

however i think you may be on the other end of that subjectivity

Reliability equals - 20 years and still going strong (sticking with reccomended tune up and fluid changes of course)


The mercuiser 454 370 hp and it's 420 hp big brother engine coupled to the borg warner 72 transmission and trs outdrive package you have is second in reliability only to the mercruiser 4 cylinder 120 hp alpha 1 package if we're only talking mercruiser engines and sterndrives.


start by determining if the engines transmissions and drives can be refreshed.


Small external engine components upgrades sure, exhaust upgrade if still stock absolutely but that mid/late 80's engine trans and drive your boat was equipped with has been doing the deed for nearly 40 years now so i'd want that all day everyday, just freshened up.


my opinion.