Your opinions: complete 4.0 swap or just 4.0 head swap? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Your opinions: complete 4.0 swap or just 4.0 head swap?

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineThe RuffStuff "I can't go to EJS" Sale!FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye Kit

Reply
Unread 06-26-2005, 07:17 PM   #1
'83Laredo
Registered User
 
Join Date: Apr 2005
Posts: 43
Your opinions: complete 4.0 swap or just 4.0 head swap?

I have the chance to buy a complete running early-mid '90s Jeep p/u truck (I think it was the Comanche?) for $500. It has the 4.0.

My 258 was rebuilt by the previous owner. It doesn't have many miles on the rebuild.

Should I rebuild and swap in the whole 4.0 w/MPFI, or just use the 4.0 head and MPFI on my 258 block?

I want something that will run on regular gas (87) and have a significant power increase. What would you recommend?

'83Laredo is offline   Reply With Quote
Unread 06-27-2005, 05:57 AM   #2
jadams68
Registered User
1984 CJ7 
 
Join Date: Aug 2002
Location: Downingtown, PA
Posts: 2,898
I wouldn't swap in a high mileage 4.0L from that commanche to replace your rebuilt 258.

If you were engine swapping, find a low milegage 4.0 from a cherokee or grande cherokee.

I just rebuild my 258 and put a 4.0L HO head on it. I run a Howell TBI injection system and I'll be finishing it and firing it up within a week.

I'll post my results.
__________________
-----------------------
I used to own two CJ's...Perhaps a 3rd is in the future?
jadams68 is offline   Reply With Quote
Unread 06-27-2005, 06:48 AM   #3
'83Laredo
Registered User
 
Join Date: Apr 2005
Posts: 43
I would have either the entire 4.0 rebuilt if I went that route, or just the head rebuilt if I went that route. I'm definitely not putting a non-rebuilt engine in the CJ.

Doesn't the 258 have more torque at lower RPMs?

Has anyone ever had the 4.0 head/258 block combo on a dyno to actually see the results, instead of estimates? I've read that this combo gives you the best of both worlds, but I haven't seen any data to back it up.
'83Laredo is offline   Reply With Quote
Unread 06-27-2005, 06:57 AM   #4
jadams68
Registered User
1984 CJ7 
 
Join Date: Aug 2002
Location: Downingtown, PA
Posts: 2,898
The 258 does have more low end torque and the 4.0L HO head has a better design to draw fuel/air and push out exhaust more efficiently.

The net is close to 40hp, but you're right...no one has dyno'd this... I will definitely do that and report.
__________________
-----------------------
I used to own two CJ's...Perhaps a 3rd is in the future?
jadams68 is offline   Reply With Quote
Unread 06-27-2005, 07:15 PM   #5
rcsutton
Registered User
1980 CJ5 
 
Join Date: Oct 2003
Location: Highlands, NC
Posts: 370
jadams will your new engine be running on 87 octane? I'm watching your rebuild.
__________________
1980 CJ 5. Hummer Yellow. SS dash, Rhino Lining 258 23 Gal gas tank Rock bumper Fnt & R. 8000# Ramsey Patriot Winch. Painless wiring. 411 gears OX rear Aussie front, dual batteries,Optima Red top, Firestone Destination M/T 33X 12.50 H12 Head Lights, Rancho 9000, Superlift, FAST EZ EFI, 18 in off road Led LIGHT BAR, Cobra CB, DUI ignition, Twin stick etc $$$$.
rcsutton is offline   Reply With Quote
Unread 06-27-2005, 08:11 PM   #6
TheJunkMan2005
Registered User
1988 YJ Wrangler 
 
Join Date: Dec 2004
Location: Lebanon, Ct, Lisbon, Ct
Posts: 741
Where can I find a write up on this online? I've junked out 5 or 6 cherokee/commanche trucks in the last few months, and didn't realize this was worthwile.. I don't want to tie up this post with with this is good and such, but a websight about it would be cool.

TheJunkMan2005
__________________
1988 Wrangler 89000 miles, no rust, no rot, all nice and pretty.. Runs down the highway really nice too.. This is great fun.
TheJunkMan2005 is offline   Reply With Quote
Unread 06-27-2005, 08:26 PM   #7
n3480h
Registered User
 
Join Date: Apr 2003
Location: IA
Posts: 162
I believe you can find info on this at http://www.geocities.com/cantwait_forviolence/

This is Geer Hed's site, one of the best collections of CJ info I've seen.
__________________
[COLOR=Red]Good Lord, this game is expensive![/COLOR]

Building a new '83 CJ7 one part at a time.
n3480h is offline   Reply With Quote
Unread 06-28-2005, 05:25 AM   #8
jadams68
Registered User
1984 CJ7 
 
Join Date: Aug 2002
Location: Downingtown, PA
Posts: 2,898
I honestly don't know if it will run on 87 without pinging, but there's 3/4 of a tank of 87 in it now and that's what it's going to be broken in on.

At this point I simply need to wire it up and put on the fenders and grill...then turn the key... my goal is to fire it on or before July 5th...
__________________
-----------------------
I used to own two CJ's...Perhaps a 3rd is in the future?
jadams68 is offline   Reply With Quote
Unread 06-28-2005, 07:33 PM   #9
rcsutton
Registered User
1980 CJ5 
 
Join Date: Oct 2003
Location: Highlands, NC
Posts: 370
Quote:
Originally Posted by jadams68
I honestly don't know if it will run on 87 without pinging, but there's 3/4 of a tank of 87 in it now and that's what it's going to be broken in on.

At this point I simply need to wire it up and put on the fenders and grill...then turn the key... my goal is to fire it on or before July 5th...

Hope there are no fireworks. Keep us posted.
__________________
1980 CJ 5. Hummer Yellow. SS dash, Rhino Lining 258 23 Gal gas tank Rock bumper Fnt & R. 8000# Ramsey Patriot Winch. Painless wiring. 411 gears OX rear Aussie front, dual batteries,Optima Red top, Firestone Destination M/T 33X 12.50 H12 Head Lights, Rancho 9000, Superlift, FAST EZ EFI, 18 in off road Led LIGHT BAR, Cobra CB, DUI ignition, Twin stick etc $$$$.
rcsutton is offline   Reply With Quote
Unread 05-22-2011, 05:04 AM   #10
o2tj
Member
 
o2tj's Avatar
2001 XJ Cherokee 
 
Join Date: Apr 2005
Location: Jeffersonton / NOVA, Va
Posts: 416
Its really worth getting the 4.0 (or head swap) in a old cj. I love mine. Nothing like reaching in the window and turning the key an having it fire right up. You can follow my build here:
http://novajeepers.net/index.php?topic=819.0
o2tj is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.