I have a 98 scarab 22 with a 454 and a carb. the standard engine not the mag.It has the stock engine all except the performer rpm intake and msd iginition. Thinking about changing the heads out to some aluminum and adding some headers and cam change.What would be the best for this set up and also will work on another engine when this one finally goes.

Heads: dart iron eagle 308's........or a set of 396 large oval/closed chamber heads (these will bump your compression approx. 1 full point. Personally, I've run the iron eagles and they are a great head! The darts would keep your compression close to where its at now though and I've run the 396 heads which worked extreamly well also!

cam: call Bob @ marine kenetics (rmbuilder on this forum) for a Hud. Roller cam, etc...

Exhaust: stainless marine, gill, Dana marine....ANYTHING is better then the stockers!

I'll say this go with the Darts or the Summit SUM-152125 (same head) I just rebuilt a pair of GM 188's for about $300 more than what I had into the old GM heads I could have had all new Darts. I also had the heads, so add the cost of the castings if you need those. Another head that I love is the AFR 265 a bit more money but it has better mid-flow numbers, lighter and a smaller runner. Either way, there is another post on here about heads on a 454 and a lot of guys like the 308 darts. After looking at the flow numbers and the cost, so do I! I wish I would have gone that route!

well toke the boat out and had a good time until i started hearing a ticking noise. Pull the head off and #3 piston had a corner piece missing. i believe the stock manifold starting leaking water into that cyclindar but not sure.Time for a rebuild.dont want to go to a different block. was thinking about a 489 forged stroker kit. afr 265s cnc ported.lighting headers and a bob roller cam. what kind of power should i get from it.Not looking for a race boat just something that will run good when i have the urge

If you go 489CI, I'd maybe look at the AFR 290's. Ask Bob M, he will set you up with a nice package.

thanks i will call him before i buy any heads and get his input.

ok. i got a stupid question. I bought the boat two years ago with the guy telling me it had 89 original hours on it. Suppose to be a 330 horse 454. Isnt a 330 horse motor dish pistons with a two bolt main. I pulled the motor apart today. I believe that is the original hours. Piston walls still see the cross hatch marks on them and the bearings look brand new. the part i dont understand. It has flat top pistons, roller cam, 4bolt main with a windage tray. the number off the heads is 10114156.

all the late model low hp merc engines are 4 bolt main with roller cams and flat top pistons..where their lacking is a cast crankshaft and ****ty 3/8 rods..

your best bet is to find a forged crank and 7/16 dimple rods to make the bottom ent stout then add mini domes and a nice sey of afr's and one of bob's cams..