Go Back   Third Generation F-Body Message Boards > Tech Boards > Tech / General Engine
Sign in using an external account
Register Forgot Password?

Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 09-05-2007, 09:28 PM   #1
Junior Member
 
Join Date: Sep 2007
Posts: 3

Classifieds Rating: (0)
rebuilt gm 350 crazy bad mpg

Hello love the site. my question is I have a rebuilt gm 350 swaped into my 95 jeep wrangler my tire size is 35 12.50 an my MPG doesnt just suck it really sucks I just got it back from the shop an it had a half tank an 35 miles later I was on E now I know I should get bad mpg but should it be that bad I think my gears are 4.11's also what should a 86 gm v8 get mpg. sorry my gas tank is a 15 gallon if that helps
v8jeep is offline vBGarage Page   Reply With Quote
Old 09-05-2007, 09:33 PM   #2
Senior Member
 
Join Date: Oct 2006
Posts: 1,941
Car: 91 RS
Engine: 350 vortec
Transmission: T-5
Axle/Gears: not the best not the worst

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

well where do i start...

what did you do to the engine CR? cam? heads? what are you running for fueling? carb/efi done any tuning?

why do you think you have 4.11 gears?

i have a 91 v8 that is getting about 8-9 MPG but i am guessing that it is slightly different from yours
SpitotRs305 is offline vBGarage Page   Reply With Quote
Old 09-05-2007, 09:42 PM   #3
Junior Member
 
Join Date: Sep 2007
Posts: 3

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

well I know it has 4.11's an it has a carb I really dont know what was done to it I should find out an get back to you but it is sucking gas like a thursty ginny
v8jeep is offline vBGarage Page   Reply With Quote
Old 09-05-2007, 09:45 PM   #4
Senior Member
 
Join Date: Oct 2006
Posts: 1,941
Car: 91 RS
Engine: 350 vortec
Transmission: T-5
Axle/Gears: not the best not the worst

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

well have you changed anything on the carb? what carb is it? what do your plugs look like.. does it smell rich at idle see puffs of black smoke at any point?
SpitotRs305 is offline vBGarage Page   Reply With Quote
Old 09-06-2007, 10:40 AM   #5
Supreme Member
 
Join Date: Sep 1999
Location: Philly, PA
Posts: 5,803

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

I'd wonder if the gague is reading accurately or if the shop didn't "test drive" it while they had it. It's tough to drink half a tank in 35 miles, unless you have a fuel leak. If it was burning that much gas you'd be belching black smoke out the tailpipe and it would be running bad to the point you couldn't help but notice it.
Damon is offline vBGarage Page   Reply With Quote
Old 09-06-2007, 11:11 AM   #6
Member
 
Join Date: Jul 2006
Location: upstate NY
Posts: 167
Car: 88 GTA
Engine: 355
Transmission: TH350
Axle/Gears: 3.42 Auburn Pro

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

I had a 96 Chevy K1500, and for awhile ran 35x12.50 Thornbirds. It had 3.73 gears. It sucked gas like you would not believe. It takes a lot to turn tires that big. I estimated my mpg in the 6 to 7 range.
jtrescot is offline vBGarage Page   Reply With Quote
Old 09-06-2007, 08:25 PM   #7
Junior Member
 
Join Date: Sep 2007
Posts: 3

Classifieds Rating: (0)
Re: rebuilt gm 350 crazy bad mpg

yea I think I am going to put some 33's on the jeep an get the carb looked at also get a tune up.
v8jeep is offline vBGarage Page   Reply With Quote
Old 09-06-2007, 09:13 PM   #8
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 12,950
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)
Send a message via AIM to xpndbl3
Re: rebuilt gm 350 crazy bad mpg

my suburban has 36s, 3.73 gears, no overdrive and tips the scales at 8200 pounds and still gets 8-9mpg in the city and 11-12 on the highway. 5.7L tbi truck, just FYI
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 09-06-2007, 09:13 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Tech / General Engine

Tags
350, bad, carb, chevy, gas, gm, gm350, mileage, mpg, puffs, rebuilt, smoke
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 04:09 AM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2012, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.5.2
All content copyright © 1997 - 2012 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details