Mercruiser 470 (3.7) big block 4-cyl. question...

[marioc]

After a year of gathering parts, getting the motor working, fixing the wiring, etc...it's time for the outdrive!

The outdrive(lower) that came with the boat had all kinds of maintenance issues. Finally I bought an outdrive from a great I-boat member.

My questions is this, the upper that came with my boat had a 1.98 gear ratio. The one I bought, came from a reputable owner, has a 1.84 ratio. He ran it on his 470 since new...
Would the 1.98 work with the 470 and a 23 pitch prop? For now, I am looking to run the 1.98 and maybe change the prop. I might be "under-working" the engine. Is this correct?

Also, I was told that here is an I-boats member with all kinds of 470 configurations(haven't been able to find him on here).

Thank you!

Mario

 

[Bamaman1]

Re: Mercruiser 470 (3.7) big block 4-cyl. question...

Mario: I found a website that addressed gear ratios, and it said the 1.98 gear ratio is what's used on a 120/140 motor.

I had a 140 hp on an Aristocraft with a 1.98:1 gear, and it used a 21 pitch prop.

 

[marioc]

Re: Mercruiser 470 (3.7) big block 4-cyl. question...

Mario: I found a website that addressed gear ratios, and it said the 1.98 gear ratio is what's used on a 120/140 motor.

I had a 140 hp on an Aristocraft with a 1.98:1 gear, and it used a 21 pitch prop.

David,

Thanks, do you happen to have the web address?
I think the 140 marking was for outdrives made from 1969-1983.
My outdrive(that came with the boat) is marked 140. The boat was manufactured in 1982.
But, everything else looks just like yours(outdrive marked 470).



Mario

 

[marioc]

Re: Mercruiser 470 (3.7) big block 4-cyl. question...

David,

Thanks, do you happen to have the web address?
I think the 140 marking was for outdrives made from 1969-1983.
My outdrive(that came with the boat) is marked 140. The boat was manufactured in 1982.
But, everything else looks just like yours(outdrive marked 470).



Mario

David,

I think I just found it... Seiler Marine - Mercruiser Gear Ratio Chart

M

 

[Don S]

Re: Mercruiser 470 (3.7) big block 4-cyl. question...

All this Gear ratio, and what fits what information is available right here on this forum. All you have to do is check out the Mercruiser information in the stickies. Very first link in this thread from the sticky.

http://forums.iboats.com/mercruiser...cellaneous-mercruiser-information-329915.html

 

[marioc]

Re: Mercruiser 470 (3.7) big block 4-cyl. question...

All this Gear ratio, and what fits what information is available right here on this forum. All you have to do is check out the Mercruiser information in the stickies. Very first link in this thread from the sticky.

http://forums.iboats.com/mercruiser...cellaneous-mercruiser-information-329915.html

Don,

Thank you for the input!

M