Which outdrive will fit my motor?

[Blueghost924]

Hi, I have a 4 cylinder Mercruiser 470 3.7L engine. I currently don't have an outdrive, but which models will fit my engine? I was thinking the 80s Alpha 1 gen 1 or 2. Thanks.

 

[Scott Danforth]

Re: Which outdrive will fit my motor?

I believe the 470's had a 470 specific MC1, however I am going off of memory.

 

[Bondo]

Re: Which outdrive will fit my motor?

Hi, I have a 4 cylinder Mercruiser 470 3.7L engine. I currently don't have an outdrive, but which models will fit my engine? I was thinking the 80s Alpha 1 gen 1 or 2. Thanks.

Ayuh,.... I believe the 470 was dead, 'n gone, before the Gen.II was introduced,...

So,... An Alpha 1, with 1.84:1 gear ratio is what ya need,...

Even if yer's was originally a MC-1, the Alpha 1 will bolt right on, 'n run just fine,...

 

[thumpar]

Re: Which outdrive will fit my motor?

Make sure you get the correct drive shaft length. I know some used different lengths.

 

[cruzn]

Re: Which outdrive will fit my motor?

Make sure you get the correct drive shaft length. I know some used different lengths.

No, I don't believe there were different drive lengths. Outboards had 20" or 25" shafts.

 

[Blueghost924]

Re: Which outdrive will fit my motor?

Aye...thanks for the info.

 

[thumpar]

Re: Which outdrive will fit my motor?

No, I don't believe there were different drive lengths. Outboards had 20" or 25" shafts.

This is an I/O. On some Mercs I/Os they had 2 different drive shaft (shaft from the engine in the boat to the outdrive) lengths.

 

[Bondo]

Re: Which outdrive will fit my motor?

This is an I/O. On some Mercs I/Os they had 2 different drive shaft (shaft from the engine in the boat to the outdrive) lengths.

Ayuh,.... That's Correct,....
Only the In-line motors, from GM, when used with the MC-1 drive, use the just over 8" input shaft,....

All the other combinations usin' the MC-1, Alpha 1, Alpha 1, Gen.II, 'n many of the Bravos, use the just over 9" input shaft on the drives,...

 

[Blueghost924]

Re: Which outdrive will fit my motor?

Do you think an Alpha 1 from the 1983-1990s year range with a gear ratio of 1.98 : 1 work?

 

[Bondo]

Re: Which outdrive will fit my motor?

Do you think an Alpha 1 from the 1983-1990s year range with a gear ratio of 1.98 : 1 work?

Ayuh,... That'll depend on what prop pitch worked properly with the 1.84 ratio,...

 

[Blueghost924]

Re: Which outdrive will fit my motor?

I was told that the Alpha 1 with a 1.98 :1 will bolt on fine and work properly, but because of the different gear ratio than a stock ratio, it will get up on plane faster but lose some top end speed.

 

[thumpar]

Re: Which outdrive will fit my motor?

It is not that you will lose top end it is that you will over rev the engine unless you can find a prop that will compensate.