2.73 to 3.42 swap, Fuel milage? Please help - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #31 (permalink)  
Old 12-20-2011, 06:57 PM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls/Suncrest, WA
Posts: 5,285
Wiki Edits: 9

Thanks: 113
Thanked 139 Times in 130 Posts
Here's a couple of calculators.

http://www.wallaceracing.com/gear-speed.php

http://www.race-cars.net/calculators...alculator.html

    Advertisement
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #32 (permalink)  
Old 12-21-2011, 09:16 AM
chevroletman223's Avatar
Dan The Man
 
Join Date: Oct 2009
Location: Remsen, NY
Posts: 24
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks again for all the help guys! i apreciate all of your input! I think what i may end up doing is putting a set of 3.36's in, and if its revving too high for me on the highway, later in the year i could find an overdrive to stick in to compensate. What would be an easier swap? a 700 or a 200?
Reply With Quote Quick reply to this message
  #33 (permalink)  
Old 12-21-2011, 10:06 AM
Houston54's Avatar
Member
 

Last journal entry: 1954 Chevy Truck Project
Last photo:
Join Date: Mar 2005
Location: Houston, Texas
Posts: 272
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I had a similar question awhile back and went with 3.42s based on responses I got here. This is a 10 bolt posi I was rebuilding to replace a 2.41 10 bolt posi I had under my 54 Chevy truck with a 355/TH350.

I drive the truck daily and found that while the performance was much improved off the line the cruising RPM turned out to be higher than I am happy with. I was getting 18-20 MPG previous and now am lucky to average 15 MPG in daily commuting.

If I were to do it again I would choose 3.08 gears for a street driven setup unless you change to an OD transmission. Then the 3.42 would be fine in my opinion.
Reply With Quote Quick reply to this message
  #34 (permalink)  
Old 12-21-2011, 10:17 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,477
Wiki Edits: 0

Thanks: 20
Thanked 386 Times in 362 Posts
Quote:
Originally Posted by chevroletman223
Thanks again for all the help guys! i apreciate all of your input! I think what i may end up doing is putting a set of 3.36's in, and if its revving too high for me on the highway, later in the year i could find an overdrive to stick in to compensate. What would be an easier swap? a 700 or a 200?
I'd keep your current gears and do the trans swap first.

If you want to do an OD trans and gears then going with a 3.73 rear gear and either a 200r4 or a 700r4 will be fine. Without the OD the gears will be a pain in the ***, and with your current gears the OD will make your engine lug alongnad can create a lot of problems. a TH350 and 2.73 rear gears is fine for cruising on the highway and if its a healthy engine you will have no problem around town. You can also step the stall up a little (not too much though with 2.73 gears) if you want more pep off of a stop light.
Reply With Quote Quick reply to this message
  #35 (permalink)  
Old 12-21-2011, 10:40 PM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,023
Wiki Edits: 0

Thanks: 0
Thanked 24 Times in 24 Posts
much cheaper to put in a th350. And would yield much better results

first gear in a th350 is 2.52:1

first gear is a 2 speed is 1.70.

so installing a th350 would be like putting in 4.04 gears in with the 2 speed (in first gear).


2.52 x 2.73 = 6.8796:1 would be the 1st overall ratio for the th350 with a 2.73 gear.

1.70 x 4.04 = 6.868:1 would be the ratio with 2 speed and a 4.04 gear in 1st gear.

top gear would remain the same.

2nd gear in the th350 is 1.5:1 (almost like 1st gear in the guide)
Reply With Quote Quick reply to this message
  #36 (permalink)  
Old 02-18-2012, 10:56 PM
Banned User
 
Last photo:
Join Date: May 2011
Location: N.E.
Posts: 385
Wiki Edits: 0

Thanks: 9
Thanked 6 Times in 6 Posts
Actually, someone posted the chart online, so i just link to it:

http://www.wallaceracing.com/reargear.htm


It's copywrited stuff, so i have mixed feelings.............
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
fuel swap pearlman55 Engine 2 12-25-2010 12:51 AM
SBC for milage ? monzter Engine 20 03-12-2010 08:30 PM
Gas milage 78 monte Engine 7 09-01-2005 04:10 PM
S.b. Milage bo 1972 Engine 1 02-05-2005 08:12 PM
gas milage on a bbc 427 bet on black Engine 18 01-03-2005 01:32 PM


All times are GMT -6. The time now is 06:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.