4.3 to 350?

[faty]

hey guys , i have an 88 fourwins horizon 4.3 cobra and i want to pute a gm 350 so my question is besides the motor itself what exactly am i gonna need to complete the swap?can i get a coupler plate to mate the motor to my trans or do i need one for the 350 then how do i mate that to the cobra outdrive? annyways anny info will be greatly apreciated ,im a car guy not a boat guy so im not shure even how the whole system works so ir annyone has a diagram or something i would love for you to email it to me. THANKS ALLOT faty373@yahoo.ca

 

[Bondo]

Re: 4.3 to 350?

Do you have the Space in the Motor Well ????????<br />The Best way to go about it,<br />Is Buy a Bob-tail Complete Engine........<br />There's Very Little you can Salvage off the 4.3.....<br />The Actual Coupler Should be the same part.....

 

[faty]

Re: 4.3 to 350?

im pretty shure i have the space it seems i saw someone with the same boat as me on this forum and i think he said he got the boat with it already installed so i imagine it fits ,but what exactly is a bobtail?

 

[Lou C]

Re: 4.3 to 350?

You also have to check the gear ratios in the outdrive, they are different from the V-6 to the V-8. I have the V-6 in my 88 Horizon 200, there does seem to be enough room for a V-8, but another issue is the motor mounts may have to be moved foward relative to where they are on the V-6. As Bondo said, most of the stuff on the engine is different, so a complete engine with starter, carb, alternator, and exhaust system is the way to go. Make sure the rest of the boat is solid first (transom, stringers, floor, etc) before you dump major money into it.<br />Another issue is that you have to make sure that the new V-8 exhaust will match up to the V-6s Y-pipe (may come up at a slightly differnt angle).<br />If it were me I'd just get a Rochester 4bbl for the V-6 if you have a 2 bbl now, it is a LOT of stuff to change on what is an old (but nice and well made) boat. The 4bbl 4.3 moves the 2650 lb 200 Horizon along pretty nicely.<br />Now if the engine and drive were both shot, as in have to be replaced, I'd bite the bullet and drop in a new Volvo SX/ 4.3, you can buy them for a little over 7 grand, and that would give you a new boat relability wise. The Volvo will fit the cut out in the transom for the OMC Cobra with no alterations.

 

[Jdeagro]

Re: 4.3 to 350?

Why do you want to change to a larger heavier power plant? What is the current WOT speed now?

 

[faty]

Re: 4.3 to 350?

right now wot is around 35mph mind u i dont want to go 80 mph i just like to wakeboard and my friend just sold his x-star so i will always have a full crew and the boat really doesnt want to come out of the water even if im not pulling annyone so thats about the reason ,ive had the boat three seasons now and last season it seemed like the 4.3 had even less power (maybe i was used to the mastercraft)but it just doesnt seem right,annyways guys i dont know what to do? is it normal to take off and iff i dont move people to the front the boat will never come out and plane it will just keep pushing water with its nose up till i get some weight in the front.

 

[Walt T]

Re: 4.3 to 350?

You say Horizon, I assume it's the 180 Horizon. I boated with a friend who had one with the 4.3. He could do 45 mph and had zero problems pulling skiers.<br />I suggest you look for a problem such as the hull filling with water or a serious drag problem before you commit to an engine.<br />Do a compression test on your current engine. Is the hull clean? Is the engine running properly? is the carburetor opening up to WOT? What prop is on it now? what is the WOT RPM?<br />Something definetly isnt right here. The 4.3 is a pretty good little motor.

 

[faty]

Re: 4.3 to 350?

ya its a 180, the hull is clean,it has no water in it so i guess ill start with a compression check if im gonna keep that motor ,can i fit a four barrel carb and whats the deal with the air filter its nothing like a car filter its so thin i think for shure its restricting the air flow? does anny one know what the motor was before omc outfitted it for a marine engine,gm,ford etc...and what would happen if i replaced it with an engine out of a truck that was the same size(4.3) could i use it? at least for a few seasons?

 

[Walt T]

Re: 4.3 to 350?

You can indeed put a 4 bbl on it. It is a GM 4.3 same as a car engine, but it is marinized.<br />The 4bbl wont help you get on plane faster, but will give you more top end. Check it over carefully and check the prop, it may not be the right prop. Verify the engine condition before you go shopping. Hate to see you waste money.