4.2L engine, is there any way to make it move? - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-09-2013, 02:40 AM   #1
Newb
 
pj174208's Avatar
 
Join Date: Sep 2012
Location: Smithtown
Posts: 12
4.2L engine, is there any way to make it move?

My 1990 has the good old 4.2 in it, and she is slow as hell and has no power. Once im at around 50 MPH I have to really get on it to go anywhere. It has a webber carb, and 148K on the clock, AX-15 with 3.07 gears, on 31's. Any ideas on how to get a little more pep out of it without doing a hell of a lot of work? Im thinking about the 350 swap, and going to 4.10s but thats a bit down the road... any ideas on what to do for now? Or is 50 mph it unless im going down hill with the wind pushing me

pj174208 is offline   Quote Quick Reply
Old 06-09-2013, 04:16 AM   #2
Jeeper
 
c5wagner's Avatar
 
Join Date: Apr 2013
Location: Reno, Nevada
Posts: 1,444
If you live in an area without tight smog regulations, pull it out and replace it with a chevy v6 or v8. I also suggest pulling a ford 8.8 out of an explore if you do so

__________________
1989 Base YJ, 4.2l, Borla exhaust, offy intake, Motorcraft 2150 carb, CRT HEI ignition, ax15, np231 JB conversions SYE, D30 ARB & Ford 8.8 ARB 4.56, 35x12.5r15 Goodyear MTR's, bds 3.5" springs, 1" body lift, and 1/2" Boom Shackles.
Build Thread: http://www.wranglerforum.com/f330/fi...ld-385106.html
c5wagner is offline   Quote Quick Reply
Old 06-09-2013, 05:17 AM   #3
Supporting Member

WF Supporting Member
 
Gunner's Avatar
 
Join Date: Jun 2012
Location: Seal Beach
Posts: 7,318
Do your swap to the 4.10's and it will be a different jeep.
Gunner is offline   Quote Quick Reply
Old 06-09-2013, 06:36 AM   #4
Jeeper
 
indirocz28's Avatar
 
Join Date: Feb 2013
Location: Fort Hood/ BCS, TX
Posts: 1,052
I don't really have much of an issue with mine. It goes great except for trying to fly a brick.

130k mi, oil change, tune up, motorcraft 2150 carb, nutter bypass, 8* timing, fuel filter, new cat, muffler and tail pipe.

Runs great!

Only time I really need to mash it is if I want to accelerate up hill while doing +70-75, and if I want to pass someone and accelerate.

But it holds 70-75 on the highway just fine.
__________________
MY1990 "Little YJ" Build: http://www.wranglerforum.com/f8/brou...ay-242064.html
Come wheel with us at Brazos Valley Off Road Ranch! http://www.wranglerforum.com/f53/bra...tx-237657.html
indirocz28 is offline   Quote Quick Reply
Old 06-09-2013, 06:57 AM   #5
Newb
 
pj174208's Avatar
 
Join Date: Sep 2012
Location: Smithtown
Posts: 12
If I put a webber on is there any point to doing the nutter bypass? Or should I just advance the timing a bit and see how it goes? And how do you advance it?
pj174208 is offline   Quote Quick Reply
Old 06-09-2013, 09:34 AM   #6
Jeeper
 
indirocz28's Avatar
 
Join Date: Feb 2013
Location: Fort Hood/ BCS, TX
Posts: 1,052
You can do the nutter even on the stock carb. The nutter has nothing to do with which carb you are using. It simply is there to keep the computer from controlling the ignition timing.

You need a timing light, and you will adjust it by turning the distributor to adavance Kr retard the timing.

However, if you don't already know what I am talking about, or how to do timing, then find someone who does. It isn't something you want to mess up. It isn't that hard, but it needs to be gentle.
__________________
MY1990 "Little YJ" Build: http://www.wranglerforum.com/f8/brou...ay-242064.html
Come wheel with us at Brazos Valley Off Road Ranch! http://www.wranglerforum.com/f53/bra...tx-237657.html
indirocz28 is offline   Quote Quick Reply
Old 06-09-2013, 10:41 AM   #7
Newb
 
pj174208's Avatar
 
Join Date: Sep 2012
Location: Smithtown
Posts: 12
I know how to do it, just never did it on a jeep before
pj174208 is offline   Quote Quick Reply
Old 06-09-2013, 10:55 AM   #8
Jeeper
 
indirocz28's Avatar
 
Join Date: Feb 2013
Location: Fort Hood/ BCS, TX
Posts: 1,052
It's the same. Make sure you take off and plug the vacuum advance.
__________________
MY1990 "Little YJ" Build: http://www.wranglerforum.com/f8/brou...ay-242064.html
Come wheel with us at Brazos Valley Off Road Ranch! http://www.wranglerforum.com/f53/bra...tx-237657.html
indirocz28 is offline   Quote Quick Reply
Old 06-10-2013, 09:38 AM   #9
Jeeper
 
Surfinglbi23's Avatar
 
Join Date: Nov 2009
Location: Haddonfield, NJ
Posts: 275
I would do gears right away. 4.10 will feel like 50 HP easy. It's that big of an improvement.
__________________
1995 Wrangler 2.5
2006 Lexus RX330
2007 KTM 300xc
1999 Suzuki DR350
2000 Wrangler Sahara - bought new, now sold
Surfinglbi23 is offline   Quote Quick Reply
Old 06-10-2013, 10:13 AM   #10
Newb
 
pj174208's Avatar
 
Join Date: Sep 2012
Location: Smithtown
Posts: 12
Thats for when I get the 350 though, problem with my 4.2 after 2500 rpm it sounds like she is guna throw something, and dosnt really have much power
pj174208 is offline   Quote Quick Reply
Old 06-10-2013, 10:45 AM   #11
Jeeper
 
indirocz28's Avatar
 
Join Date: Feb 2013
Location: Fort Hood/ BCS, TX
Posts: 1,052
How is your oil pressure? Have you checked your timing?
__________________
MY1990 "Little YJ" Build: http://www.wranglerforum.com/f8/brou...ay-242064.html
Come wheel with us at Brazos Valley Off Road Ranch! http://www.wranglerforum.com/f53/bra...tx-237657.html
indirocz28 is offline   Quote Quick Reply
Old 06-10-2013, 11:05 AM   #12
Jeeper
 
roadyrob's Avatar
 
Join Date: Apr 2012
Location: west palm fla
Posts: 1,017
how much money do you want to spend? the 4.2 will make plenty of power if you do the right upgrades. mine beats my neighbors stock 4.0 with no problems. but I have a fresh motor, balanced, head milled, casting cleaned up and port matched, rv cam, offenhauser manifold with a holley 390cfm 4 bbl, HEI ignition and 2 1/2" magnaflow cat and muffler.
the best for the money would be the HEI ignition, the manifold and carb and the larger exhaust.
if your jeep has an old exhaust I would do that first, the 4.2 exhaust is very restrictive even when new.

roadyrob is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user 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.



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 Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 09:38 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC