Jons999

Im looking at buying an 83 Scarab 30 foot. It has 2 330hp Mercruisers, completely stock except for aftermarket thru-hull exhaust. A friend of mine has an identical Scarab that came with 2 400hp engines. What are the differences between the 2 engines? If i buy the boat it would be nice to get an extra 140 reliable horsepower if its something simple like a cam and head swap.

phragle

iTrader: (3)

Oh boy...buckle up, this thread could get bumpy. Without writing a book on the various iterations of different merc motors we will give you the readers digest version,

Both are most likely 454s and chevy based.

the 330 will have a cast crank and weaker rods, the 400 will have a forged crank and beefier rods

the 330 is most likely a 2 bolt main, the 400 a 4 bolt main

The 330 will have peanut port heads, the 400 will have antiquated GM rectangle port heads

The cams, intake manifolds, and carbs will be different.

As for the 140 hp, a cam, valvetrain and decent heads would do it. reliably depends on what parts you choose and how you run it.

Now for the buckle up part... you will get 400 different opinions on whether to do it, how to do it etc.... the 2 bolt cast crank bottom end will handle 450~500 hp as long as you dont beat the hell out of it or try to rev it past 5k regularly and put it together right.

90viper

iTrader: (1)

The only thing they share is the block. The 330 is a very reliable base engine in its stock form. cast crank, small rods,cast Pistons, small oval port heads. The 370,400, and 440 are out of high performance with similar internals as the 454/450hp and 502/500hp. I remember back in the day a 400hp upgrade was like $3500 each. Hope this helps. Merry Christmas

90viper

iTrader: (1)

Very well stated phragle

Jons999

Thanks guys. This will be my first boat, i am a mechanic by trade so i'm not scared of having to fix a few things but i don't want this to turn into a huge project. In your opinions, am i better off paying cash for an older boat like this and spending a couple thousand on the engines to make it run 65-70 mph, or should i finance a little bit nicer of a boat that i won't have to upgrade? To me the 1980's Scarabs were always one of the coolest boats out there, but i'm disappointed that the only one i see for sale locally has the 330hp engines.

cyrus77

iTrader: (4)

Actually the block is different.
Different pistons, rods, crank, cam, rod bolts, heads, block, intake, carb, etc, not sure if a single engine part is the same. Rectangular port BBC are entirely different animal. More heavy duty. 330 HP can be upgraded in power but BBC rect port are a better starting point.

SB

iTrader: (1)

Like old cars, worry more about the condition of the vehicle itself more than it's powertrain....Difference between the two, is vehicles metal rot while boats wood rot.

Worst thing ever is to buy a boat or car without knowing if the vehicle is good or not and jumping right in and spending money on the mechanicals all to find out that it was wasted $$$ and time.

If you really want this boat, have it surveyed. Because of the age of the boat, expect an unpleasant survey. Just going by a % bet.

Don't get emotionally involved and skip getting the boat checked out.

hblair

Great advice given here. Like SB said, be sure the boats not rotten for starters. The transom and stringers will be your most likely places for rot. If you don't have it surveyed at least tap it with a hammer. Sharp tap=good, dull thud=pass (or price goes down because there's lots of work to be done). Tap the engine stringers, transom, pull the storage covers from the cockpit floor and tap those stringers too. Read my thread "79 scarab 300 resto" to see what you're in for if its rotten.

I don't know when the peanut port heads started but you can pull a valve cover and see what your head stamping numbers are, if yours end in 049 you have the large oval port heads. I had mine reworked for larger valves. 2.19 intake and 1.88 exhaust. Doing this, going with a bigger cam and an air gap intake to go with your a/m exhaust will really wake your boat up.

Just don't advance the timing too much like I did and blow your motor up, then you'll have an excuse to go ahead and upgrade to forged internals!

hblair

By the way, Post some photos!