boboznutz

So I have a 1988 formula 223 with a 330hp Mercruiser that is shot. I just made a tenative deal on a 454 that is 60 over and is fresh from the machine shop with 4 bolt mains, forged scat crank, crower rods, 10.5 to 1 comp and rectangle port heads with a bunch of port work. It was built for a jet boat and has a crazy tunnel ram with two dominator carbs on it. It also comes with a victor jr manifold that I plan to use.
My questions are should I use a single dominator or sell them both and get a nice new 850? Also the big question is on the cam, it has a hydro roller cam from isky in it that is 284/294 advertised duration 578/608 lift and 110 lobe seperation.
http://www.summitracing.com/parts/ISK-396284-294/
Will this cam work or should I just switch it out now before I put the motori n?
Also I am running a 21p mirage prop and I am guessing it will need to go as well????
And one last question for now how bad will all this be with stock mercruiser cast iron manifolds? I just cant come up with the cash right now for another 2 grand in exhaust.

Thanks in advance, This place is such an important resource for newbies like me!

BillK

bobo,
The cam is not all that bad considering the compression.

That being said, do you plan on running this thing on pump gas ? If it has cast iron heads, I would plan to be running some type of racing fuel. Even with aluminum heads, 10.5 to one is too much in my opinion for 93 octane, especially in a boat. I would not want to see much more than 9.5 with cast iron heads, and that is probably pushing it.

Just my opinion,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

boboznutz

I had not thought about that, I will look into it. Thanks, this is just the kind of advise I was looking for!

Sunrocket24

You will need better exhaust with that cam to prevent reversion, and you will need to re-prop the boat because that engine will make allot more HP than your stock engine. And you will have to run 93octane at minimum, might need more. I'm not an expert but I took allot of great advice from people on this forum with the new engine I built for my boat (I went mild but I'm happy), and my new engine has been running great for 17 hours so far. I'm sure more people will chime in here to help you out also.

endeavour32

In my opinion the compression is way to high. I would say that 9.5:1 is max for iron heads which I see Billk thinks the same.

If you haven't bought the engine yet, I have a 525 hp BBC engine I'll make you a great deal on... Professionally built and designed by on of the best Marine Engine guys around. If pushed my Formula 242 to 68 MPH (GPS) I'm sure your 223 would be in the low 70's!

jeff1000man

oh wait. I jsut re read your original post.

No way that cam works with that exhaust. Sorry man.

IMO, from experience, just rebuild the one you have until you have money to spend on exhaust.

You can't really upgrade anything practical with tht exhaust.

The only practical upgrade for what you have is to go with a merc 502 cam that you can get pretty cheap on here, just put something out there and one of the guys will have one. Upgrade your heads to a large oval chevy with good valves and springs, have your machine shop put a good 9-9.5:1 piston in it, and then you will have a stronger engine with your stock exhaust and no reversion. Pick up maybe 50Hp on paper. Someone will have a good set of those heads on here somewhere that you can pick up cheap. They are the best 454 upgrade out there. If they do some port and polish work on them then they are even better.

When you can afford new exhaust, then change the cam to match the exhaust and you will have a 500+- Hp engine.

Put a tall single plane intake on it with a good 750 carb.

there is a lot of experience on this board with 454's as they have been experimented on with to death. There is really no reason for you to spend your own money on an experiment.

jeff1000man

If you look around on here enough, you might even find a guy with a single engine boat that will be selling a complete take out with exhaust that might be a few dollars more than you want to spend, but it could be a bad ass engine at .50 on the dollar.

boboznutz

I need to double check the compression ratio but i am shocked that 10.5 to 1 is too high.... I am no motor guy by any means but my buddys v drive is 13 to 1 on 110 fuel and he has 990 heads with temp gauges on them and they run cool????

As far as your engine I think it would most likely be out of my price range... I am paying 2800 for this motor and the guy has 8k in recipts just in parts.

Thanks

jeff1000man

a v drive and a jet boat is nothing like an offhsore boat, but do what you want.

No way that cam works.

boboznutz

Ok, what if I spen the 300 or so for a new roller cam that is way more mellow, loose some power for now then put a better cam in when I get money for exhaust? Sounds silly but the engine is such a good deal I hate to pass.
Or... are there any exhaust options that dont cost a fortune? What about the 496 manifolds with the stainless risers, are they a good option?
Thats why im here... agree 100%