3.0L cobra vs 2.3L cobra

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agwa2111

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I had my 1988 3.0L Cobra outdrive replaced. It had no reverse.

The mech replaced upper & lower with used cause he had one at the shop.

I's the gear ratio the same on the 3.0L and the 2.3L? How can I tell which one he put on? Ser #?

The reason I ask is the boat would do 40 mph before now all I get is 24. The only thing that is different is the out drive.

I get 4600 rpm just 24 mph.
 
Bondo

Bondo

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Re: 3.0L cobra vs 2.3L cobra

The only thing that is different is the out drive.
Click to expand...

Ayuh,... What about the Prop,..?? What pitch is it,..??
 
Don S

Don S

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Re: 3.0L cobra vs 2.3L cobra

The the 87 -90 2.3's had a 2.00:1 gear ratio, the 3.0's had a 1.71:1 ratio.
in 86, both were 1.71.
Did you get 4600 rpm before.
 
LilRedNeckGirl

LilRedNeckGirl

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Re: 3.0L cobra vs 2.3L cobra

somewhere on here, there is a sir # guide to determine whats hangin on the engine pushin you around. sounds like prop to me. check size & pitch. 4600 rpm. That would prompt me to look at the MFG specafacations to see what the RECOMENDED max RPM is. I run a 3.0 and seems my manuel says something around 4200 as max rpm, and that cruising should be around 3000 rpm.
Im thinking if your not at a comfortable cruise, up on plane and livin the good life at 3000 rpm's, something needs fixing... Remember, its a 4 cyl marine engine, not a weed whacker.
 
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agwa2111

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Re: 3.0L cobra vs 2.3L cobra

I've tried a 13 , 15, 17 with mixed results. 13 made rpms run high and less mph 17 more top end and less rpm. Yes I was running 4600 rpm with 15 pitch prop before I had the drive changed.
 
Bondo

Bondo

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Re: 3.0L cobra vs 2.3L cobra

Ayuh,... Ya did leave the trailer in the parkin' lot, Right,..??

It sounds like there's Something else goin' on...
 
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agwa2111

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Re: 3.0L cobra vs 2.3L cobra

I've tried a 13 , 15, 17 with mixed results. 13 made rpms run high and less mph 17 more top end and less rpm. Yes I was running 4600 rpm with 15 pitch prop before I had the drive changed.
 
A

agwa2111

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Re: 3.0L cobra vs 2.3L cobra

Yes there is something gonnin on. I'm thinking he put a 2.3 cobra on instead of 3.0. Not sure how the 2.0:1 ratio would effect performnce.
 
Bondo

Bondo

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Re: 3.0L cobra vs 2.3L cobra

17 more top end and less rpm. Yes I was running 4600 rpm with 15 pitch prop before I had the drive changed.
Click to expand...

Ayuh,... A 17" or 19" Should give you about the Same performance as it had before,...
IF it's the lower gear ratio...
 
A

agwa2111

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Re: 3.0L cobra vs 2.3L cobra

I guess the only way to truely find out which drive
I have is to take it apart and look. thx for the responses
 
T

tschmidty

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Re: 3.0L cobra vs 2.3L cobra

Or mark the prop and turn the engine over one revolution and see how much the prop moves!

24 MPH, 4600 RPM is way too little prop or a gear ration that is significantly off. 13 15 17 are all relatively small props especially if the ratio is a 2.0:1 with a 3.0
 
A

agwa2111

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Re: 3.0L cobra vs 2.3L cobra

Update Just took the plate off the top off out drive and counted the gears. The top gear had 23 splinds. I thought the 3.0L had 21 splines.

Did I mention the out drive came off of a pontoon boat that had 3.0L OMC.
 
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