470 to 4.3 swap

[hadaveha]

Ok guys I have looked this forum over from stem to stern, and I have found a bunch of different answers. SO can I pleaze layout my situation. I have a 1984 mercruiser 470 with a alpha1 outdrive. I am looking to replace it with a 1995 mercruiser 4.3 the engine comes to me with everything from balancer to coupling, I allso have the Ypipe. so with that being said A. will the outdrive mate up, B. will my drive rato be right. and C. am I a idiot and should just rebuild the 470. I know with the 4.3 I will have to fab some mounts, but Im hoping with the Ypipe the exhaust will mate up.
ThankYou every one for all the help
david

 

[thumpar]

Re: 470 to 4.3 swap

I think I remember reading that the transom plate was different on the 470. The drive ratio is correct.

 

[achris]

Re: 470 to 4.3 swap

Ok guys I have looked this forum over from stem to stern, and I have found a bunch of different answers. SO can I pleaze layout my situation. I have a 1984 mercruiser 470 with a alpha1 outdrive. I am looking to replace it with a 1995 mercruiser 4.3 the engine comes to me with everything from balancer to coupling, I allso have the Ypipe. so with that being said A. will the outdrive mate up,

Yes.

B. will my drive rato be right.

Also yes.... Originally the 4.3 was supplied with a 1.84:1 ratio (same as your 470), but as the output of the 4.3 increased the ratio was dropped to 1.62:1. Personally, I prefer the higher reduction, you can run more efficient props.

and C. am I a idiot and should just rebuild the 470. I know with the 4.3 I will have to fab some mounts, but Im hoping with the Ypipe the exhaust will mate up.

Yes, the Y-pipe will mate up to the ransom plate. You might need to clean up the bolt holes with a tap though (I would)....

ThankYou every one for all the help
david

No, you're not being an idiot... (that's my provience )... The 470, as good as it WAS, is old now.... You'll love the 4.3....

Chris......

 

[stonyloam]

Re: 470 to 4.3 swap

am I a idiot and should just rebuild the 470.

Hmmmm I think you will be a lot happier with the 4.3 Just make sure you part out that 470, lots of valuable parts there. Just don't mess up the winterization and wind up with a cracked 4.3 block (just a little something to worry about ).

 

[Bondo]

Re: 470 to 4.3 swap

Ayuh,.... Partin' out the 470 oughta pay a fair chunk of the 4.3,...

The 4.3l is a decent motor,... I'm runnin' a 95ish 4.3LX,.....

 

[achris]

Re: 470 to 4.3 swap

Ayuh,.... Partin' out the 470 oughta pay a fair chunk of the 4.3,...

The 4.3l is a decent motor,... I'm runnin' a 95ish 4.3LX,.....

And it has a nice METAL timing cover. :facepalm:.....

 

[Bamaman1]

Re: 470 to 4.3 swap

The transom plate on the 3.7 will not fit the 4.3.

The only way to do this conversion is a 100% swap out--motor/transom plate/out drive/electrics. . . . . . everything.

And if you're not a really good mechanic, forget it.

I hate to be blunt, but it's the truth. At $100 per hour, getting a marine mechanic to do the job is just not cost effective.

 

[matt167]

Re: 470 to 4.3 swap

i think that's true for drives 1983 and prior. I think the first 3.7L Alpha's were standardized to use the same transom plate as the then upcoming 4.3L ( 1985 IIRC )

 

[hadaveha]

Re: 470 to 4.3 swap

This is what ive been talking about we have 2 or 3 different opions as to what will have to be done swap the 470 with the 4.3. once again because im slow and im from Alabama the 1984 470 will swap with a 1995 4.3 without changing the transom plate and the outdrive I hope anyway right

 

[achris]

Re: 470 to 4.3 swap

..... I have a 1984 mercruiser 470 with a alpha1 outdrive. I am looking to replace it with a 1995 mercruiser 4.3 ...

The transom plate on the 3.7 will not fit the 4.3.

The only way to do this conversion is a 100% swap out--motor/transom plate/out drive/electrics. . . . . . everything.....

i think that's true for drives 1983 and prior. I think the first 3.7L Alpha's were standardized to use the same transom plate as the then upcoming 4.3L ( 1985 IIRC )

Bamaman, Matt is correct. Have a look at the parts listing for R,MR and Alpha One drives. All use the same gimbal housing (outer transom plate) and inner transom plate, and all had 120hp, 140hp, 3.7, 4.3 and SBC engines mounted in front. The ONLY difference was the exhaust pipe. A straight pipe for the in-lines and a Y-pipe for the Vs.

As for drive, the SAME drive used on all engines. The difference being the ratios, and in this case, the 4.3 uses the same ratio as the older 3.7, 1.84:1.....

Chris......

 

[achris]

Re: 470 to 4.3 swap

This is what ive been talking about we have 2 or 3 different opions as to what will have to be done swap the 470 with the 4.3. once again because im slow and im from Alabama the 1984 470 will swap with a 1995 4.3 without changing the transom plate and the outdrive I hope anyway right

In a word..... Correct....