350 to 454 conversion
#12
Registered
Join Date: Oct 2003
Location: Colleyville, TX
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
I ran a 87 veleocity with a Alpha drive and 454 magnum 330HP that was massaged with no reliability issues on gears. Boat was 2800 lbs. Without nose cone speed is limited with stub nose on that drive. With cone and 23 Pitch ran 71 mph. Definitely had that boat in the air 8 or nine feet before. Clutch dog wear is problem make sure you use srping loaded shift assist came out in 1989 or jam it in. Easy shifting will wear clutch dog. Also ran a land and sea torque shift prop and that boat literally jumped out of the water. Taught a few lessons to jet boats on acceleration. Top end stayed at 67 with torque shift prop but you could out accelerate most cars .
Also had a friend who put 400 hours on 86 24 foot 4 Winns Liberator with 454 1.36 Alpha and 19 pitch.
Also had a friend who put 400 hours on 86 24 foot 4 Winns Liberator with 454 1.36 Alpha and 19 pitch.
#13
VIP Member
![](https://www.offshoreonly.com/forums/images/icons/prop.gif)
![Default](/forums/images/icons/icon1.gif)
I have a friend with a 1987 24' Formula 454mag/330HP hooked to an alpha 1.32 ratio. The drive lasted over four hundred hours before blowing apart. So you can run a a low output 454 on an alpha for a while.
I like the idea of building up the 350 better though...
Good Luck!
I like the idea of building up the 350 better though...
Good Luck!
__________________
Patrick
Patrick
#14
Registered
![Default](/forums/images/icons/icon1.gif)
on a 2800 lb boat the drive is no problem, my buddy runs a 330 hp with alpha in his 26 searay 8000 lbs. and it takes it running 40 mph.
I think MKast spelled it out pretty clear it is very easily possible, and alot of the brackets, exhaust etc are available from 2nd hand suppliers cheap.
The only question is the weight, liberator put out a 20 ft 330 alpha it was okay. but a SB built would be good just more expensive by the time you get it built properly.
I think MKast spelled it out pretty clear it is very easily possible, and alot of the brackets, exhaust etc are available from 2nd hand suppliers cheap.
The only question is the weight, liberator put out a 20 ft 330 alpha it was okay. but a SB built would be good just more expensive by the time you get it built properly.
#16
Registered
Thread Starter
![Default](/forums/images/icons/icon1.gif)
Originally posted by Tinkerer
ARE you shure that is not a 305...
The old Merc 188 HP was a FORD 302
The old merc 198 HP was a Chevy 305
ARE you shure that is not a 305...
The old Merc 188 HP was a FORD 302
The old merc 198 HP was a Chevy 305
#17
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/charter_member_star.gif)
Join Date: Jan 2001
Location: so. WI
Posts: 1,562
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Originally posted by yellowbird
My question is what simple bolt-ons will make the most gains on my 350/260. headers, cam and carb? What brand of cam and duration please.is a carb swap nessisary for a mild bump like this? What kinda hp could a stock 260hp with exshaust carb.and cam provide.
My question is what simple bolt-ons will make the most gains on my 350/260. headers, cam and carb? What brand of cam and duration please.is a carb swap nessisary for a mild bump like this? What kinda hp could a stock 260hp with exshaust carb.and cam provide.
I think you will destroy the handling qualities of your boat if you install a BBC in there; you'll be much better off building a good mouse. Definitely pick up a copy of Dennis Moore's book on building the marine SBC- lots of good info in there.
![Wink](/forums/images/smilies/wink.gif)
Jim
#18
VIP Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
![Default](/forums/images/icons/icon1.gif)
I took a 1992 Larson senza 25'4" stepped hull boat
running 49mph with a 350 mag 270hp crank, 250 prop hp AND houston prop worked the Laser II prop
225.00 ,I put a set Of EMI thunders Used 350.00 "good shape one year old" Corsa Quick & quiet used "like new" 325.00 plus a new harness 120.00, K & N air cleaner with a snub stack, Plus I reset the timing.
my Wot is now 54-55 depending on how many people are on board
so I spent very little and I have thur hulls which sound faster
5-6 mph gain @ WOT
3-4 in the mid range RPMS
with a boat this sized it should have had a BB from the factory, But this is pretty good for what HP its getting
running 49mph with a 350 mag 270hp crank, 250 prop hp AND houston prop worked the Laser II prop
225.00 ,I put a set Of EMI thunders Used 350.00 "good shape one year old" Corsa Quick & quiet used "like new" 325.00 plus a new harness 120.00, K & N air cleaner with a snub stack, Plus I reset the timing.
my Wot is now 54-55 depending on how many people are on board
so I spent very little and I have thur hulls which sound faster
![Big Grin](/forums/images/smilies/biggrin.gif)
5-6 mph gain @ WOT
3-4 in the mid range RPMS
with a boat this sized it should have had a BB from the factory, But this is pretty good for what HP its getting
Last edited by wwwTOPDJcom; 11-18-2003 at 09:17 PM.
#19
Guest
Posts: n/a
![Default](/forums/images/icons/icon1.gif)
Seriously... the 454 is only 100 - 150 lbs heavier than the 350, so go with aluminum heads and intake on the 454... same ol, same ol... except it will wake that boat up and run like a raped ape... The way to know if you REALLY want to do this is to ask yourself this question
:Do ya wanna FISH, or CUT BAIT? lol
:Do ya wanna FISH, or CUT BAIT? lol