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  #16 (permalink)  
Old 08-27-2013, 10:39 AM
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ChrisCraft

Bob, Those are some sweet boats. As mentioned by others here, seems to me that you need to determine what gear ratio you have in your outdrive to make a good decision on which engine to use. You could have a 1.5:1 or a 1.65:1 depending on which 305 you have.
If I were in your shoes, I would size the engine according to the drive ratio to avoid having to spend additional cash to get the gears changed to match the engine. If you have the 1.65:1 set, I'd recommend staying with a replacement 305. If you have the 1.5:1 set, then I'd be tempted to go with a replacement 350/260 and enjoy some additional top speed with little more than a prop change and still be able to snatch some tubers or skiers out the water.
Fact is that if you put a bigger cam in a 350 or put a 383 stroker engine with a decent cam, then you have to start upgrading the intake and exhaust systems to allow the engine to breathe better and the costs really start climbing.
Ask me how I know. My 20 ft. Eliminator Sport Cruiser 406 SBC
Here's a chart on the Alpha 1 outdrives;
Seiler Marine - Mercruiser Gear Ratio Chart
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  #17 (permalink)  
Old 08-27-2013, 12:50 PM
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Going to respond from a v-drive boat guy. Just please be careful to not put too much power in a boat that the hull was not designed for. I have seen it before with disasterous results... Sounds like your not going too crazy, but certain types of boat hulls were designed for specific duties and speeds.
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Old 08-27-2013, 12:59 PM
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Quote:
Originally Posted by BobBoat View Post
I'm not to concerned with fuel mileage, the gas seems to be the cheaper part of boating. I said something to my wife about getting a used engine and she didn't seem to interested. She said we do enough boating that a new engine seems to be the right path. we talked abouanother 305 and she said " ask them guys about building a bigger engine with more power, because the kids are getting older and are gonna wanna go tubing eventually." The boat didn't care much for a two person tube before so we just don't do it that much. if we had more power we might use it more. with that being said.....
Would you suggest the same camshaft if it was in a vortec 350 engine? I was also doing some googling and seen that a few guys are running the gm performance 7395 camshaft Chevrolet Performance Hydraulic Roller Camshafts 14097395 - Free Shipping on Orders Over $99 at Summit Racing my buddy was telling me this would be a bad camshaft for a boat, I don't know why he says that he just says because it would be.

Would you select a different cam profile if I was going to use a roller cam?
This cam is used a lot of boat engines.It doesn't look very good on paper,but,it performs well.Provides a very flat torque curve out to 4500.has a pretty much smooth idle in a 350.A little lope to it in a 305.it's also easy on the valve train.You can get off Ebay ,(new pullouts) for $99 to $120.
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Old 08-29-2013, 08:58 AM
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Alpha 1 Stern Drives

I'm not sure if the OP is still here, he has stopped responding. Just for information for future readers of this thread, I wanted to point out a fact about marine propulsion. A V-drive, direct drive, jet pump, or a stern drive all have their RPM limits.

When it comes to an Alpha 1 stern drive, the outdrive has an RPM limit of 5000 RPM, better longevity at less (4800). One of the reasons the drive is limited is because above 5000 RPM the centifugal force of the spinning ring gear in the upper gear case will sling all the oil off in a vortex allowing the oil to cling to the case and run the ring and pinion with less than enough lubrication and cause failure.

With this fact in mind, engine power building practices should focus on building max power below 5000 RPM. Does no good to put huge heads and huge cams designed for high RPM power, when you start exceeding 5000 on an Alpha 1 you will destroy it soon or later.

This is one of the reasons you see so much difference in opinions about horsepower building in boats. Engine horsepower/torque/rpm limits have to be matched to the propulsion system being used. Nolan
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Old 08-29-2013, 09:03 AM
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Quote:
Originally Posted by BobBoat View Post
talking about the drive: if a new larger/ more efficient engine was installed and the prop remained the same it wouldn't be any harder on the drive than the old engine, would it?

I don't plan on racing the boat anytime soon. The majority of what we do is float in the lake and get sunburnt. It gets to expensive to fly around the lake all day. Maybe twice a year we get the two person tube out and tow it around the lake.

This is the best picture of the boat I could find.
Ayuh,.... Talkin' 'bout yer Drive Bob,... What drive is it,..??

'n yer ole 305, is it a 2bbl. carb, or 4bbl. carb,..??

About what Vintage are We talkin',..??

Dependin' on yer answers,...
Yer most likely, cheapest, easiest way to satisfy yer Love,(the Wife, not the boat ) is to plunk down yer cash at yer local Chevy Dealer, 'n buy a brand new pickup motor from GM,...
Either the 350, or their 383,...
Just the Long Block motor, with tin,...
They come with brass core plugs, 'n composite head gaskets,...
The cam is plenty close enough to do what you need,...

You'll be able to use most of the accessories from yer ole motor(dependin' on yer answers)...
You'll need an Intake, 'n probably an Electric fuel pump kit,... Marine uses an O/P shut-off switch,...
'n a standard Chevy Flywheel,...(14", dependin' on yer answers)

Lookin' forward to yer answers to my questions,...
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  #21 (permalink)  
Old 08-29-2013, 10:03 AM
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A blower would be sweet

I have given thought to a small blower, it would make some nice power right where you need it.

However, I've tryed to remain conservative with my lil Alpha 1.

I spent boatloads of money(pun intended)on an old piece of junk OMC 800, blew it up countless times. I finally did a total transom rebuild and converted mine to the Mercruiser Alpha 1.

A little history on the Alpha drive; Mercruiser ran this drive with different power plants up to a 365 hp 454. When the warranty work started costing them alot of money they realized they had pretty much found the HP/Torque limitations of the Alpha with the BBC. Thats when the Bravo was born, built to take the brutal torque of the BBC.

I wish I could have afforded a Bravo drive for my boat, but at the time a complete Bravo was more than double the cost of an Alpha. I've got a 502 Mercruiser I could drop in it now but it would likely twist the Alpha into a pretzel.

Without giving away all my secrets, the best way to build a high performance engine for a stern drive is too; 1)realize the torque limitations of the outdrive. 2) Try to utilize engine components around achieving the most torque and horsepower you can get on the chart @ 5250 where the two cross. If you have to make a compromise between the two, always go with the package that makes the most torque in that 5000 rpm window. Nolan
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Old 08-29-2013, 12:42 PM
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sorry guys I'm still here. for some reason I'm not getting emails telling me sometime has replied. I'm at work right now but will definitely reply tonight. you guys are amazing,I am very happy to have all the help.
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Old 08-29-2013, 03:10 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
Add water methanol injection will allow you to crank the boost and timing up and run "Flat out"
Without killing it. you will slay your fair share of Big blocks out on the lake with this lil blown 305.

So can your wife hold a radar gun , read the tach and scream my name at the same time ?
how much would a build like this cost?
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Old 08-29-2013, 08:45 PM
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the blower build definitely is interesting. maybe I'll make my way to Canada after retirement and hire your for a consultant during the build . but for now I think we are going to go with a regular engine. I did some looking at the drive today and I seen it has 1.65 stamped on it. I hope this won't be a lost cause or a deal breaker. I am interested in some advice about building the engine to use this drive. but also, Is it expensive to change the gear ratio to a preferred/ better ratio?
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  #25 (permalink)  
Old 08-30-2013, 06:15 AM
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Quote:
Originally Posted by F-BIRD'88 View Post

When you get it wide open and all trimmed up only about 6" of the back of the boat's hull will be in the water at all
@ speed.

And if you are lucky, you wont encounter the "fun" (terror?) of chine walking at 60 mph with many You Tube vids showing that experience.
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Old 08-30-2013, 10:13 AM
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Bob, Give Mike Jones a call at Jones Cam Design. He is very knowledgable and familiar with boat engines. He does cams for many different applications including Jersey Skiffs, Cracker boxes and Hot Rods. He knows what "water reversion" is unlike the tech guy I spoke with at Comp Cams.
He will hook you up.
Richie
watch what cam you have or put in there. seems reversion is only a factor to the boat owner not the cam company. i mean that. reversion could hydrolock the engine, worst case blow a rod through the block or light case scenario it will rust your exhaust valve and seats and compression will be down after a couple seasons. also chine walking is very dangerous and overpowering a boat is the one way to get you ejected from your boat. usually whene you get ejected, unless you have a tether cord your boat will turn hard around and go in tight circles at whatever speed you were at at the time of ejection, around where your floating in the water. that would be some pretty scary stuff. i see your wife is leaning tward a new engine but you cant buy a "good" choice built 305 engine in a crate. just stockers. but a 305 can make good torque if you build it with flattops .040 over pistons and vortec l31 heads. or even 081's would work well and you wouldnt have to buy an intake to match the heads. your q-jet would need a little tuning but your ignition will work great and drive ratio would be fine. that will save you some money and get you going a good bit better than the old power plant. i love a 305 and have relied on em for years glad to hear you wouldnt mind keeping a 305. i recomend you go .040 over and make it a 311 but either way a 305 is good. wont set the world on fire but there small displacement and high torque is a appreciated at the pump and they are super super reliable probably because they dont run as "hard" as other engines. if you have the old log style exhast then throw them in the scrap pile and get some newer header style upright manifolds from the late 80's early 90's alphas. they work very well on a 305 even through the prop. the prop while spinning, actually pulls exhaust from the engine like a vacume so once rpms are established thru-hull exhaust doesnt do anything for a 305 compared to thru-prop. its those crappy log manifolds holding the exhaust back. loose em.

Last edited by s-10again!; 08-30-2013 at 10:33 AM.
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Old 08-30-2013, 08:57 PM
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Quote:
Originally Posted by BobBoat View Post
the blower build definitely is interesting. maybe I'll make my way to Canada after retirement and hire your for a consultant during the build . but for now I think we are going to go with a regular engine. I did some looking at the drive today and I seen it has 1.65 stamped on it. I hope this won't be a lost cause or a deal breaker. I am interested in some advice about building the engine to use this drive. but also, Is it expensive to change the gear ratio to a preferred/ better ratio?
I can agree with everybody about how much fun a blown boat can be,, but they can and WILL be very expensive if you think you have to have that throttle on the floor too much
I had a 18 Ft Pantera jet with a Blown 383 small block chev, and 2 other motors , (all 3 were blown latterly),,,,all within a 3 year period,, pretty expensive boating,, but on the other hand,, you don't have to run them full bore all the time,, its just so much fun to go fast,
I no longer have a boat,,,

Bill
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Old 09-02-2013, 09:37 PM
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I just happened to be talking to a co worker Friday and I was talking to him about my boat. When I told him that I'd really like to get a Vortec engine and rebuild it he said his brother was talking about scrapping his 98 Chevy 1500. So he called his brother and just so happens he still had the truck. His brother told him it is a vortec 350 with 250,000 miles. After work I went over to his brothers house and looked at everything. Didn't hear the engine run but he said it ran fine when he parked it but it's been sitting for a few years. So for two hundred bucks,I pull the engine then haul the truck to the scrap yard for him the engine is mine.

I plan on a total engine rebuild. So I am building a vortec 350 for the boat. Would still like suggestions on building this engine now that we know for sure of the size.
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Old 09-02-2013, 09:42 PM
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take the engine apart and see whats good?
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  #30 (permalink)  
Old 09-02-2013, 10:04 PM
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Keep in mind, if your current motor is the 2bbl version, than going to a 350 will require a new outdrive leg because the ratios are off. It's 1.65 vs 1.5 for the 350. I wouldn't be surprised if your 1984 boat has a 1983 stern drive which is not an Alpha. What are your S/N's? They are forward compatible as in you could put an Alpha leg on an "MR" drive but not the other way around
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