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Discussion Starter #1
I posted in the on the dyno section and didnt get many responses so I will try it here.

I have a 77 hawaiian 24' Day cruiser with a BBC 454 and a Berkley 12JG jet w/ Place Diverter.

The motor is a 73-90 2-4 bolt main with harman logsfor exhaust and a stock steel intake manifold and a holley 750 The heads are 73-84 049 oval port 122cc Chamber 255/119cc port. ignition is stock as well.

The pump is a berkley 12j with a Hyd/ Place diverter and I think a AA impeller. and A hp grate. the motor spins to 4800 at 45mph.

its a little slow for my taste. from other people tell me it has a great hole shot for such a big boat. but no top end.

what mods should I start with to free up some power? my first major purchase will be lightning headers. but that wont be this season.
any input is greatly appreciated. Thank You
 

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I posted in the on the dyno section and didnt get many responses so I will try it here.

I have a 77 hawaiian 24' Day cruiser with a BBC 454 and a Berkley 12JG jet w/ Place Diverter.

The motor is a 73-90 2-4 bolt main with harman logsfor exhaust and a stock steel intake manifold and a holley 750 The heads are 73-84 049 oval port 122cc Chamber 255/119cc port. ignition is stock as well.

The pump is a berkley 12j with a Hyd/ Place diverter and I think a AA impeller. and A hp grate. the motor spins to 4800 at 45mph.

its a little slow for my taste. from other people tell me it has a great hole shot for such a big boat. but no top end.

what mods should I start with to free up some power? my first major purchase will be lightning headers. but that wont be this season.
any input is greatly appreciated. Thank You
Try an "A" impellor. That will let the engine spin up more. 4800 is about right for a stock package.Not much more hp too free up. The lightnings arnt really going to get you anything that you will notice really. Just my opinion, The lightnings on my engine when it was stock bumped about150 rpm's. Not much of a gain for the money,but they work well on the new engine...:D
 

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If your spinning a AA impeller to 4,800 with a stock BBC then either your tach is off or your pump is shot. Spinning an A to 4,800 would be something with logs. That said a 24' boat will take alot of power to move and 45 is doing pretty good with your stocker. Not trying to be a downer but if 45 don't get it for you and you want a jet you might have the wrong boat. Or you could throw a ton of hp at it along with a ton of $$$$ and get 55mph maybe.
 

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Discussion Starter #4
a solid 50 would be great, im thinking along the lines of a intake manifold ignition and headers, Greg shoemaker told me to flip the boat and true the bottom end and id see a big difference but that is a ton of money.

If your spinning a AA impeller to 4,800 with a stock BBC then either your tach is off or your pump is shot. Spinning an A to 4,800 would be something with logs. That said a 24' boat will take alot of power to move and 45 is doing pretty good with your stocker. Not trying to be a downer but if 45 don't get it for you and you want a jet you might have the wrong boat. Or you could throw a ton of hp at it along with a ton of $$$$ and get 55mph maybe.
 

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a solid 50 would be great, im thinking along the lines of a intake manifold ignition and headers, Greg shoemaker told me to flip the boat and true the bottom end and id see a big difference but that is a ton of money.

If you get a sweet spot with those headers and intake you might pick up 300-400 rpm but most likely you'd need a cam change too. If you have an A impeller then that would be somewhere near 450hp, I just don't think it will get there. Maybe around 390hp or so. But the real problem is lifting the boat to free up some mph. That is a big heavy boat that is producing alot of drag and will take more than a few 100 rpms to increase it's speed. Really not meaning to sound so negitive just know it's a tall order.
 

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Discussion Starter #6
yea I wish it were lighter,I love the layout it is perfect for my family so I dont want to change boats.jan at lightning said id see 75 hp with the headers, not sure what else to try a couple of people suggested a droop snoot but I thought they were for smaller lighter boats.
If you get a sweet spot with those headers and intake you might pick up 300-400 rpm but most likely you'd need a cam change too. If you have an A impeller then that would be somewhere near 450hp, I just don't think it will get there. Maybe around 390hp or so. But the real problem is lifting the boat to free up some mph. That is a big heavy boat that is producing alot of drag and will take more than a few 100 rpms to increase it's speed. Really not meaning to sound so negitive just know it's a tall order.
 

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E-7 Sheepdog (ret)
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Lot of good info here.

If you are actually pulling an AA to 4800, that's some stock motor. I would get a confirmation on the tach, then check the pump condition. That would be arround 400HP on a well-loaded pump as opposed to arround 350 on an "A" at the same RPM.

My stock 330HP 454 spun an "A" 4800/4850 for decades if the pump was tight, would not get an AA anywhere close, 4500 MAYBE. It MAYBE made 280HP, pretty typical from what I gather.
.461/.480" lift, about 270* duration was original, dual plane intake, log exhausts.

When I began modding the motor, (Performer RPM Air Gap manifold, cam change from stock to .565" lift, 280* total duration, no exhaust changes), I also added a good loader to replace the modded grate, and came out even in the RPM, 4800 solid. More HP but more load.

Then I added Lightning headers and picked up 200 RPM even.

This spring the head porting will be seen. WOOO HOOOO!!!!!
 

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E-7 Sheepdog (ret)
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yea I wish it were lighter,I love the layout it is perfect for my family so I dont want to change boats.jan at lightning said id see 75 hp with the headers, not sure what else to try a couple of people suggested a droop snoot but I thought they were for smaller lighter boats.
If the heads, cam, and intake are choking on the exhaust, MAYBE. I saw 50HP.

IMO I got rid of the worst problems first with the cam and intake, then replaced the logs, and now the heads (stock small-valved '049 castings) are the restrictor point (just ported this past winter).

What exactly IS this motor setup? My changes have not been what I would consider terribly expensive (OK, $1800 for the Lightnings and $1800 for the head work are serious chunks on my budget).

My cam and intake were under $700 total (but I did need pushrods too (tiny 5/16" ers stock) and the stock factory rockers won't like it. I found a deal on a used set of Comp Hy-Tech stainless rolelrs and got them overhauled, for less than new Pro Magnum steels.
 
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