4.3 Cobra leg on a 3.0

jajin2004

Cadet
Joined
Jan 29, 2009
Messages
9
Second post regarding the 4.3 cobra leg I have. I asked a similar question on February 1st only it was using the 4.3 on a 5.0. Now I want to know if the 4.3 (gear ratio 21:19) can work on a 3.0. The person states the year of the boat is 1989 so the gear ratio is either 21:18 (pre 1989) or 21:21 (post 1989) Also, Cheifalen answered my last inquirey with some ratios that I don't understand and don't really know what they mean, could he explain them and answer this question with those ratios please. thank you
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 4.3 Cobra leg on a 3.0

A drives gear ratio is designed for one size engine.
One gear ratio for a 3.0L
One for a 4.3L
One for a SBC V8 (5.0 or 5.7)
One for a Big block

They are that way for a reason. Props only have a specific range in which they work most effectively. To keep that range in props satisfied, you have to change gear ratios in the drive.
It wasn't something done by manufacurers just to pissoff the DIYer and make him spend more money than he wanted to.
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: 4.3 Cobra leg on a 3.0

I gave it straight from the book the drive ratios in your last thread, putting a 4.3 leg on a 5.0 motor would work. not putting a 4.3 leg on a 3.0 motor that won't work.

What didn't you understand from the last thread ??

I thought you had the motor and the drive already !

And you still didn't post what hp the motor from the last thread had ?

What else you want to know just ask ?
 
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