Engine swap questions

[borderdog]

1995 Stingray 606zp
4.3 w/mercruiser Alpha1 gen II

I believe a spun a rod bearing on the motor this weekend. Weighing my options at this point and have a few questions.

If I decide to put a 350 motor in the boat, how much of what I have from the 4.3 will bolt onto the 350. Ex. exhaust manifolds, bell housing etc.

Is a 350 compatible with the outdrive currently on the boat.

Any comments or input is appreciated.

Thanks all!

 

[stonyloam]

Re: Engine swap questions

1995 Stingray 606zp
4.3 w/mercruiser Alpha1 gen II

Is a 350 compatible with the outdrive currently on the boat.

Thanks all!

The gear ratio would be wrong, 1.81 (4.3) vs. 1.47 (5.7).

 

[lime4x4]

Re: Engine swap questions

you will also need new intake manifold,exhaust manifolds

 

[borderdog]

Re: Engine swap questions

Thanks for the information. Ill just go with the 4.3 and keep it simple.

Thanks again!

 

[180shabah]

Re: Engine swap questions

This would be a good opportunity to get a vortec engine. This would require a new intake manifold, but the exhaust manifolds and everything could be reused. Significant gains in power and still 100lbs lighter than a 350.

 

[Friscoboater]

Re: Engine swap questions

How would the exhaust manifolds work? isn't the 4.3 a v6?

 

[wca_tim]

Re: Engine swap questions

1995 Stingray 606zp
4.3 w/mercruiser Alpha1 gen II

I believe a spun a rod bearing on the motor this weekend. Weighing my options at this point and have a few questions.

If I decide to put a 350 motor in the boat, how much of what I have from the 4.3 will bolt onto the 350. Ex. exhaust manifolds, bell housing etc.

Is a 350 compatible with the outdrive currently on the boat.

Any comments or input is appreciated.

Thanks all!

IF you have room, everything but the exhaust WILL WORK FINE. You'll need to move the front motor mounts a few inches forward. All the brackets, etc... should be the same. Since you should really put a new exhaust on a new engine anyhow (I would to be safe I think unless it is fairly new and in good shape already). So you would need different elbow / connectors to mate the v8 exhaust with the y-pipe. Your distributer will even work (with a different cap and two more wires of course).

You can easily use a 1.81 gear ratio and reprop to account for the difference.

If you're running a 19" now, you're looking at probably runing around a 23 when done, 21 - 25 ish, etc... that's really rough and is based on the assumptionthat you pick up around 100 horsepower and maybe 10 mph. The point is that there are many very well designed and available props in that range available for your boat.

 

[180shabah]

Re: Engine swap questions

How would the exhaust manifolds work? isn't the 4.3 a v6?

See post #4

Thanks for the information. Ill just go with the 4.3 and keep it simple.

 

[wca_tim]

Re: Engine swap questions

I was only making the point that if the choice of sticking with a 4.3 was predicated on having to replace the outdrive and so on, that was not necessarily a valid assumption. It may well be simpler to go with a smallblock / 350 than a casual read of the first several sposts would indicate... if he has the room. When repowering my current / primary river boat, I first bought and installed a non-balance shaft, vortec heads, aluminum intake, etc... 4.3 and ran it for a season. I decided that I wanted a bigger step up so went the smallblock rounte after that. Prop availability has not been an issue and the higher 1.81 gear ratio even performs better than the 1.47 in my situation. I've got a 1.47 upper gearbox and have run it with appropriate props on a couple of occassions. If I had it to do over, I would have skipped the intermediate v6 step.

So many times on here, the immediate response is that you need gear ratio x for x engine, but in reality, that's just what Merc started with as a blanket guideline - not anything near a gospel requirement.

Again, just making a point, imho,

Respectfully submitted.