Go Back  Offshoreonly.com > Technical > Drives and Lower Units
Chris craft 312 omc 460 outdrive gear question >

Chris craft 312 omc 460 outdrive gear question

Notices

Chris craft 312 omc 460 outdrive gear question

Thread Tools
 
Old 06-13-2015, 11:56 AM
  #1  
Registered
Thread Starter
 
Join Date: Jun 2015
Location: Belgium
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default Chris craft 312 omc 460 outdrive gear question

Hello everyone,

I am new to the offshoreboat world as my other hobby is jeepin, it was always a dream of mine to have an offshore boat and now I bought a chris craft 312 from 1988 with the omc king cobra engine package
But their is one thing where i'm not shure of, witch is the upper outdrive gear ratio. Because my strb upper gear is broken and now that i have taken it out i saw that my upper gear ratio is 21/16 and this sould be 21/17 with the omc 460's.
Is this bad or should i just leave the 21/16ratio and put other props on it instead of the stock ones.

Thanks Rien
Rienl is offline  
Old 06-13-2015, 12:30 PM
  #2  
BUP
Banned
iTrader: (9)
 
Join Date: Jul 2011
Location: Ft. Worth TX
Posts: 9,594
Likes: 0
Received 41 Likes on 35 Posts
Default

For the 7.5 - 460 Ford - 21 / 17 should be in the upper for this OMC Cobra OEM stock and then 21 / 18 should be in this for the High altitude apps above 5000 ft.

Last edited by BUP; 06-13-2015 at 12:35 PM.
BUP is offline  
Old 06-13-2015, 12:35 PM
  #3  
BUP
Banned
iTrader: (9)
 
Join Date: Jul 2011
Location: Ft. Worth TX
Posts: 9,594
Likes: 0
Received 41 Likes on 35 Posts
Default

Forgot 21 / 16 in the OMC Cobra upper was used for the GM 5.7 and a 21 / 17 for high altitude above 5000 ft. Again OEM OMC stock for the upper Cobra's
BUP is offline  
Old 06-13-2015, 05:15 PM
  #4  
Registered
Thread Starter
 
Join Date: Jun 2015
Location: Belgium
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks for the reply

The problem is that i can't afford two new upper gear sets including all other expences, because the port side outdrive will also have the 21/16 upper gear ratio and if i want to put it back to oem than i have to replace both :s so is there maybe an other solution ? 21/16 and an another pitch ?

Thanks
Rienl is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.