Alpha 1 Merc.170

[starsnstripers]

Whats the ratio on an Alpha 1 mercruiser 170 4cyl? could it be used on a 165 L6?

 

[achris]

Re: Alpha 1 Merc.170

Ratio used on the original 470 (4 cyl, 170hp) was 1.84:1, the I/L6 165 used a 1.65:1... You could use it (1.84 drive) in a larger heavier boat and run the next size up prop.... If, for example, the 165 with a 1.65:1 was using a 17" prop, then with a 1.84:1 it would require a 19" prop (18.9" mathematically). So I see no problem with using a 1.84:1 drive....

Just be careful with the length of the yoke. All R, MR and Alpha 1 drives use the same yoke with I/L and V engines. Your yoke is different. It's no big deal to change them, just as long as you know.

Chris............

 

[starsnstripers]

Re: Alpha 1 Merc.170

I figured the yoke would need a change. But wasn't sure on the ratio or what it was. Thankyou chris i have a 19" prop on my boat now. So i'd need a 21"?

 

[achris]

Re: Alpha 1 Merc.170

I figured the yoke would need a change. But wasn't sure on the ratio or what it was. Thank you Chris i have a 19" prop on my boat now. So I'd need a 21"?

I believe you're doing a re-build on the engine... I'd run the 19" until the engine is run in and see what you're getting with the 19" before changing it....... Remember also that you want to be at the top end of the 3900-4300 range... If you're a couple of hundred over, all the better....

Cheers...............

 

[starsnstripers]

Re: Alpha 1 Merc.170

Now on these ratios' for example- a 1.65:1 is that 1.65 prop rev. to 1 engine rev.? or vise-versa? Or is it 1.65 driven gear rev. to 1 engine rev. or vise-versa? thanks

 

[starsnstripers]

Re: Alpha 1 Merc.170

Well i found an alpha drive cheap so i was thinking a good spare

 

[achris]

Re: Alpha 1 Merc.170

Now on these ratios' for example- a 1.65:1 is that 1.65 prop rev. to 1 engine rev.? or vise-versa? Or is it 1.65 driven gear rev. to 1 engine rev. or vise-versa? thanks

1.65 engine revolutions to 1 prop rev....

 

[starsnstripers]

Re: Alpha 1 Merc.170

Auh, Ok thanks Chris appreciate the lesson.