F223LS

I have a 7.4 330hp. in a formula 223ls, someone told me that you can add a high rise intake manifold. Clean up the ports on the heads and add a 454 mag cam, and gain 4 to 5 mph. That sound right to anyone? Seems too simple for that kind of gain.

puder

while eth heads are off being cleaned upyou coudl also have them decked to raise the compression a (gen IV) 330hp 7.4 will most likey have 8.0 compression it coudl be brought up to 8.5 and have teh oprst opened up a little bit to let her breath better. The cam woudl be worth some HP. also you might consider an aftermarket exhuiasts along with the head upgrades.

Youcoudl also trade your oval port head for some quare port (mag) heads. That plus the cam should be worth some good HP.

crmax

a set of 1997- 2000 oval port heads (used on 7.4mpi) edelbrock rpm intake , 750 carb and a good cam will put you in the 380 hp area

nobudget

Dave I had made some upgrades on the 330 last year in a 1988 Searay Pachanga. I went with Imco's new Thumper Power alum exhaust, it got me 1 mph. Did testing with all things being equal
fuel amount ,octane level, weight, outside tempeture, wind and GPS.
The next week or so I put on a alum Elderbrock Intake (performer RPM) with a 650 Deamon carb and gained an honest 4 mph with matching the same peramitors as I did when I ran the exhaust upgrade by itself. Was the Imco worth it maybe maybe not but it does look cool and the boat is alot lighter for it. 68.5 best pass gps. 4500 rpms wot

port and polish the heads, go with the stainless headers buy them used if cash is an issue. intake and carb well worth the effort. Good luck and have that prop labbed.
This was my 2 cents worth.
Nobudget

Whiteknuckle

The IMCO exhaust manifolds or similiar manifolds will do little with a stock engine. However as you modify or change other components the IMCO's will allow you to better take advantage of those changes. You can bowl port those small oval heads and install the larger valves in them and it will help. However you would be much better off going with a set of large ovals like the Chevrolet 049 or 781 heads. Fred who is onthis board has a set for sale that Jim Valako set up. The rectangular port heads are far less desireable than the large ovals. Also, remember to change your pushrods on that 330 HP from 5/16 to 3/8 inch no matter which head you go to.

dyno

going to take a lot more than that to get 5mph. maybe 5hp....just kidding I've got my 7.4's over 450hp but it took heads a cam,compression,intake carb and exhaust...and got 10mph.

Whiteknuckle

Dyno
You are absolutely correct. Last year I got 422 HP with my old 330HP using the peanut port heads. This year I'm going with a little more cam and the large 049 ovals that I got from Fred. It should be back on the Dyno,( no pun intended) in about 2 weeks. Yes the horsepower come alot easier than the MPH.

EX20

Check out this month's issue of Family and Performance Boating. They do an article on getting more power out of the 7.4L 330HP. Very informative!

formula31

Sorry, I got Freds other set of heads. About the only things you really dont have to change is the ignition and the bottom end. But you might pay for not doing the bottom end. It really comes down to budget. If you do most of the work yourself, you can build a decent engine for $2000-$2500, add $1500 for the exhaust manifolds. Having learned the hard way, I spend the money on the bottom end and heads.

fstboater

I have the top ends from my merc 400 for sale see heads intake carbs for sale these parts will get you to 400 hp a little more cam and 420. A lab prop will add a couple of mph forget those small port heads any up grade will help.