350 Mag RPM - Need More???

[mister460]

Awwww, quit bein' a sissy and BIG BLOCK it!!! You'll spend duckets on that small block and then wish you'd just dropped in a big block.

[sea buddy]

You need to prop to 4,900 rpm for the ideal for this motor.
Try some testing. Move all weight aft, over the drive as best is possible. Then get the same weight forward over the bow eye as best possible.Depending on the results you may find your boat stern or bow heavy.
Where is the fuel tank? Cockpit floor, bow, or near engine?
Your rpm change to prop change is about normal. Usally plan on 200-400 rpm change per 2" in prop pitch if all else the same on both props.
Once you know if you want stern lift or bow lift you can try some props that go to give you what the boat needs.
By the way, I have seen different brand boats with warped bottoms (hook or rocker) and some that weighted over 700 lbs. more than what the factory listed as its spec. All this stuff makes a difference.

[sea buddy]

I think you have got to get this boat to run better with a 21" prop.
If I were to guess, you need to get weight off the front and let it dance on the transom.
Ask the factory and bob's machine shop if this hull will gain 6-8 mph with one of those extention spacer drives that get the trim working the bow up more--should be just what you need. Try the weight over the transom test to prove me right or wrong before you spend money. Just get the weight way, way back there even if it is in a sily way for just the one test.
Also, take a 8' straight piece of metal and hold it fore and aft against the last 7' of bottom step by step from chine to chine. Gaps along the middle=hook. Gap or curve up at the transom=rocker.

[sea buddy]

Your boat should gain 4-6 mph for every 500 lbs you can get off it, after you get it going as fast as should at this weight by getting it to dance on the transom and the bow carried out of the water.
Just think, if you could get 1,000 lbs off the boat, your current 62 mph will be 73 mph, without any other changes other than a 25" prop.
That's cheaper to do than a supercharger.

[chevy_power]

:idea: There are a few cheap things you can do to get more power without getting into the lower unit. You could go with a little hotter cam or instead of paying alot of money for aluminum heads you could put a set of 305 heads on the 350 which will give you more compression and boost your over all horse power. either way you might want to make sure you are getting a clean open exaust. Don't forget about the basics such as new plugs wires and filters. Just a few ideas. Good Luck

[Beer-30]

The easiest first steps would be a set of 1.6 roller rockers and then exhaust. You would easily see 40+ hp with these two items and even more with an ECM reflash.
Get the drive and engine on a good synthetic diet. You will get a mph or two right there.

[TIMINATOR]

The biggest roadblock to speed with an Alpha drive is the exhaust. The Bravos are larger internally and have exhaust vents between the ventilation and spray plates. Bigblock risers(the 90 deg cast iron things on top of the manifolds)are 3 1/2" and will bolt on to your smallblock manifolds in place of your 2 7/8" units. Flow bench shows about 65% improvement in flow. Most years have the 2 7/8" risers going into a rubber adaptor that goes into the 3 1/2" 90 deg bends that go down to the outdrive. This deal with a short piece of 3 1/2" hose is a big help. The better deal is to just come off of the 3 1/2" risers and go straight out of the transom, you can mount the tips below the waterline for a quieter idle if you want. ANY engine mods will not gain much power without the exhaust being done first. I have seen 8 mph gain with the big risers and thru transom exhaust on a 24' Eliminator! If yours is a carburated engine, the installation of an Edelbrock Performer RPM AirGap intake and a hydraulic cam of 270 advertised duration .470 lift. That would be 220 degrees at .050 will usually net about 3-5 more MPH. If you don't mind a rougher idle, a 280 cam (230 @.050)will give an even larger gain. We did these mods in steps to the 24 and finally added Holley systemax aluminum heads too. Total speed gains on the 24 Daytona were phenominal! Top speed now is in the mid 70s!!!!! Remember that this is a picklefork tunnel, but it IS a 24 foot boat! Most peeps are quite surprised that the engine is only a modified 260/350 small block. Insurance is small-block cheap and the looks when the hatch is opened is great fun to see! call me for more info. TIMINATOR

[Beer-30]

Good post.
I didn't notice the 1992 portion, so it should be carbed.