4.3l gave up now what?

[mjdh_80]

My mercruiser 4.3l 205 is in need of replacement. I'm planning to drop in a 350 and will probably convert a street engine to marine use. What should I look for from the new engine and how hard would it be to put in a fuel injected engine in it? Also I have an alpha 1 out drive, how much hp can those take?
Thanks in advance
Matt

 

[r.j.dawg]

Re: 4.3l gave up now what?

Your Alpha is good for 300 HP but from what I have learned from the guys here, you will have the wrong gear ratio for a V8.

 

[mjdh_80]

Re: 4.3l gave up now what?

Oooo what do I need to do to fix that? How do I know what gears i need?

 

[tpenfield]

Re: 4.3l gave up now what?

Another thing to consider is that the head gasket, cam and core plugs will be different on the marine version.
Also you need to have fuel, ignition and electrical systems that are marine compliant for use as a boat engine. So there are a lot of additional parts to swap out.

Your best best may be to get a new engine or stay with the 4.3L and just get a marine long block to replace your defunct engine.

 

[Bondo]

Re: 4.3l gave up now what?

My mercruiser 4.3l 205 is in need of replacement. I'm planning to drop in a 350 and will probably convert a street engine to marine use. What should I look for from the new engine and how hard would it be to put in a fuel injected engine in it? Also I have an alpha 1 out drive, how much hp can those take?
Thanks in advance
Matt

Ayuh,.... Unless it's a Marine fuel injection unit, it Ain't gonna happen...

V8s run the 1.5:1 gear ratio, yer V6 is probably a 1.84:1, or 1.65:1...

 

[mjdh_80]

Re: 4.3l gave up now what?

Well... fuel injection isn't a big deal , just thought it might be nice. The lower unit is what I don't know much about. (gonna have to do some work in there too tho)
Why would the cam need to be different in a marine engine? I understand the head gasket but that would be replaced during a rebuild anyway. And I was aware of the core plugs.

 

[r.j.dawg]

Re: 4.3l gave up now what?

For a marine engine, best case scenario, you would want a marine cam. They are ground to produce the maximum torque required by a marine engine. Next would be an RV ground cam. You could get by with one out of a truck but forget one from a car. They are ground for RPM not torque.

 

[tpenfield]

Re: 4.3l gave up now what?

Just a few more words about the cam shaft . . .

Marine cams differ from automotive cams in the amount of valve overlap that they have designed into them. Marine cams have less overlap. This is to prevent 'reversion', which can be a problem at idling speeds with a marine engine.

 

[mjdh_80]

Re: 4.3l gave up now what?

Oh, ok. Thank you! I've replaced a cam before and was planning on rebuilding the whole engine when I get it anyway. What are some things I should look for in an engine? Also any recommendations for the rest of the parts I'll need? Keep in mind I'm on a limited budget.
Just so I know, what is the difference between marine and auto fuel injection?
Thabks again for all your help!

 

[Howard Sterndrive]

Re: 4.3l gave up now what?

look for a truck or auto 350 - the older the better imo. Early 70's.

If you are on a budget, look for a V8 powered boat - you need the drive and you need the exhaust, ignition, fuel system etc. etc... there is no cheap way to buy all that stuff piece by piece.

In my neighbourhood, you'd find a nice boat cheaper than all that, or at least a damaged or rotten hull with the complete driveline ready to swap.

Just so I know, what is the difference between marine and auto fuel injection?

a complete answer to that would several pages...

the short answer: lots