Local dealer is telling me that 1.65 ratio is not...

[bluemarshboater]

correct for my boat. I have a 92 mercruiser 5.0 (serial OD662988) and the stamped ratio is 1.65..... the dealer is telling me this is not correct and that is for a V6 boat.

Can anyone please verify that for me?

Thanks
Dave

 

[Bondo]

Re: Local dealer is telling me that 1.65 ratio is not...

Ayuh,... The 1.65:1 is used on many 5.0l motors,...
Usually for very Large hulls or boating at high Altitudes...

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

This is a 20' some what large hull. 92 bayliner capri.

 

[HT32BSX115]

Re: Local dealer is telling me that 1.65 ratio is not...

Is there something wrong with the way it runs?

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

I think it runs fine, but the tach isn't working so don't know the rpm's at this point. The boat plains off very fast (like 3 - 4 secs). They tell me that's because it's geared so high, like pulling out in first gear.

 

[JustJason]

Re: Local dealer is telling me that 1.65 ratio is not...

Mercruiser stern drive ratio chart...

http://www.4shared.com/file/113521134/81eff60b/sterndrive_ratio.html

 

[HT32BSX115]

Re: Local dealer is telling me that 1.65 ratio is not...

Well,
You need to replace the tach.

It's the only way you can determine if your boat is running correctly.

Then, borrow a handheld GPS and use it to determine if your speedometer is correct.


Run the boat at WOT long enough to determine your steady state max RPM and speed. (don't over speed the engine......your max is probably 4800-5100 rpm.....the manual should indicate your max RPM.)

You may be able to just put a slightly higher pitch prop on it and be good to go.

You can do some "ballpark figger'n" with a prop slip calculator.
http://www.go-fast.com/Prop_Slip_Calculator.htm

You can get the "prop-slip" by leaving it blank and clicking "calculate" knowing your (accurate) RPM & speed.


With this info, you can get a feel for what the boat will do with different props. It's not an exact science ......but it will get you close.


Cheers,

Rick

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

According to that (I think).... my ratio is incorrect. Should be 2:1?

 

[cr2k]

Re: Local dealer is telling me that 1.65 ratio is not...

Isn't a 5.0 a V-8 and not a V-6?

 

[Bondo]

Re: Local dealer is telling me that 1.65 ratio is not...

According to that (I think).... my ratio is incorrect. Should be 2:1?

Nope,... Somehow,... You've got it pretty much completely Backwards....

 

[Don S]

Re: Local dealer is telling me that 1.65 ratio is not...

According to that (I think).... my ratio is incorrect. Should be 2:1?

NO, you should have either a 1.47 or a 1.50 ratio. Which is the standard ratio for GM V8 engines.

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

To be perfectly honest the left column is confusing.... I see a few 5.0's over there and can't really figure out which to go with. The right shows Alpha and bravos. Not sure how to use that chart, sorry.

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

Thanks for the info Rick, that is what I was told at the dealer too.... about I can probably correct it with a 22 or 23 pitch prop, but that was their guess.

 

[Alumarine]

Re: Local dealer is telling me that 1.65 ratio is not...

Until you get a working tach there is nothing to "correct" is there?

Thanks for the info Rick, that is what I was told at the dealer too.... about I can probably correct it with a 22 or 23 pitch prop, but that was their guess.

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

Nope. That is next to be fixed.

 

[cpubud]

Re: Local dealer is telling me that 1.65 ratio is not...

my ratio is 1.62 2000 5.0

 

[180shabah]

Re: Local dealer is telling me that 1.65 ratio is not...

1.6x is absolutely correct for your 5.0 if it is carbed, same ratio is used on the EFI v6's, while the carbed 4.3 standard ratio is 1.84.

 

[HT32BSX115]

Re: Local dealer is telling me that 1.65 ratio is not...

Thanks for the info Rick, that is what I was told at the dealer too.... about I can probably correct it with a 22 or 23 pitch prop, but that was their guess.

The "Best" way to correct it would of course be to put the "right" ratio drive on it. That might not be very cost effective (unless you have someone that is just "itching" to buy your drive for what you could buy the "right" drive for)

You may be able to make it run acceptably with a higher pitched prop. That might not be optimum but it will probably work good enough.

See if you can get a prop dealer to loan you a couple of props to try....(make sure you put a good tach on it though)

 

[bluemarshboater]

Re: Local dealer is telling me that 1.65 ratio is not...

Sorry all, but I'm still not sure whether I have, according to the charts, the proper ratio drive or not. Anyone?

It seems to me, after reading a few charts, that mine is close... I'm seeing 1.61:1, 1.65:1, etc..

http://www.seilermarine.com/info/mercruiser-drive-ratio-chart.htm

Thanks
Dave

 

[JustJason]

Re: Local dealer is telling me that 1.65 ratio is not...

You can have 1 of 3 or 4 ratio's for a 5.0 depending on which one the boat builder spec'd for your particular boat.
1.65 to 1 is 1 of those ratios.