NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old September 25th, 2006, 11:06
Root Moose's Avatar
Root Moose Root Moose is offline
NAXJA Forum User
 
Join Date: Jul 2003
Location: ON, Canada
Posts: 3,736
0630 vs 0331

Is there any real difference between these head castings other than the provisions for the DIS on the 0331?

Different chamber size? Valve size? Other things?
Reply With Quote
  #2  
Old September 25th, 2006, 11:09
MogifiedXJ's Avatar
MogifiedXJ MogifiedXJ is offline
NAXJA Forum User
 
Join Date: Jul 2006
Location: Tellico, TN
Posts: 1,047
Re: 0630 vs 0331

HO head #7120 & #0630

Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 66.0 128.0 179.0 206.0 209.0 209.0
Exhaust flow. 55.0 100.0 120.0 136.0 141.0 141.2

HO head #0331

Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 114.0 165.0 194.0 199.0 205.0
Exhaust flow....94.0 117.0 126.0 130.0 133.0

Ported big valve 2.02/1.60 HO head

Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5
Intake flow.... 73.9 142.4 197.8 229.8 247.0
Exhaust flow. 65.3 114.0 135.9 146.3 157.1

The early '87-'90 non-HO heads have low intake ports that flow rather poorly. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders. The '91-'95 HO heads with casting no.7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'98 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '99 and later HO heads with casting no.0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
The exhaust ports flow relatively poorly compared to the intake ports on all the 4.0 heads so this engine would perform better with a dual pattern cam that has more exhaust valve opening duration and lift than the intake. Jeep recognised this and increased the exhaust valve opening duration on the '99 and later cam to compensate for the poorer exhaust port flow of the 0331 head.

Last edited by MogifiedXJ; September 25th, 2006 at 11:46.
Reply With Quote
  #3  
Old September 25th, 2006, 12:52
Root Moose's Avatar
Root Moose Root Moose is offline
NAXJA Forum User
 
Join Date: Jul 2003
Location: ON, Canada
Posts: 3,736
Re: 0630 vs 0331

So can anyone provide any guidance as to whether an originally 0331 equipped engine retrofitted with a 0630 head would have issues passing emmisions?

Is the difference signifigant or would a otherwise healthy engine pass the 2001 emmisions standards even with the "dirtier" 0630 head?


I'm not needing a head swap yet... but if it comes to pass I'll try to squeak past emmisions with the 0630 head.

(we don't have visual of that "depth" - cat installed? yes, continue)
Reply With Quote
  #4  
Old September 25th, 2006, 20:54
j99xj's Avatar
j99xj j99xj is offline
NAXJA Forum User
 
Join Date: Jul 2006
Location: Colorado Springs, CO, USA
Posts: 800
Re: 0630 vs 0331

The 0630 is a better stock head. It flows better as stated above and doesn't crack as easily as the 0331. The only issue would be fabbing up some brackets to hold your igntion rail. (I'm assuming you have distributorless ignition.)

I don't think you would have any problems passing emissions with a 0630. Just make sure your engine looks clean the day of your test. You wouldn't impress a date wearing a dirty t shirt and torn jeans, and you won't impress the emissions tech with a soiled and oily engine. So get some engine degreaser after your head swap.

Another thing, if your going to the trouble of swapping heads, take this opportunity to give the 0630 head a good port/valve job. You will gain significant high rpm power if you do this correctly.

Reply With Quote
  #5  
Old September 26th, 2006, 15:15
Dr. Dyno's Avatar
Dr. Dyno Dr. Dyno is offline
NAXJA Forum User
 
Join Date: Aug 2003
Location: Al Ain, UAE
Posts: 3,446
Re: 0630 vs 0331

Avoid the 0331 heads like the plague. Apart from the fact that the exhaust ports are tiny, these heads are crack prone especially between the 60,000-90,000 mile mark (outside the powertrain warranty period so basically you're screwed if it happens).
Reply With Quote
  #6  
Old September 26th, 2006, 18:02
Fish'nCarz's Avatar
Fish'nCarz Fish'nCarz is offline
NAXJA Forum User
 
Join Date: Dec 2005
Location: Victor, ID
Posts: 724
Re: 0630 vs 0331

Buy one of the aluminum replacement heads!!!

Then tell us mere mortals how it works and show us how you did the swap!

That's what I'd have Over-Haulin' do to my XJ, boy!
Reply With Quote
  #7  
Old September 27th, 2006, 01:19
Dr. Dyno's Avatar
Dr. Dyno Dr. Dyno is offline
NAXJA Forum User
 
Join Date: Aug 2003
Location: Al Ain, UAE
Posts: 3,446
Re: 0630 vs 0331

Quote:
Originally Posted by Fish'nCarz
Buy one of the aluminum replacement heads!!!
On yeah, those heads are a bargain; Summit Racing sell them for $1400 bare and $1500 assembled, while Hesco sell them for $1850.
Reply With Quote
  #8  
Old September 28th, 2006, 18:06
falcon556's Avatar
falcon556 falcon556 is offline
I have not Confirmed, or I used a BAD email Addy
 
Join Date: Nov 2004
Location: Tulsa
Posts: 1,265
Re: 0630 vs 0331

Quote:
Originally Posted by Dr. Dyno
On yeah, those heads are a bargain; Summit Racing sell them for $1400 bare and $1500 assembled, while Hesco sell them for $1850.
$1850 per head? Definetely a bargain!
I think I'll buy two of them, I'll keep the second one in my living room for decoration purposes :-)
BTW a friend of mine bought a pair for the V8 of his Mustang. After he put them on compression and performance evaporated.
It seems that even though they were listed as replacements, he was supposed to know that the chamber volume was not identical to the original, Edelbrock told him to shave a few thousands and use a thinner head gasket.
He even had the block shaved a bit. What a cluster....

Last edited by falcon556; September 28th, 2006 at 18:11.
Reply With Quote
  #9  
Old September 29th, 2006, 06:53
CartsXJ's Avatar
CartsXJ CartsXJ is offline
NAXJA Forum User
 
Join Date: Sep 2003
Location: Glenville, NY
Posts: 921
Re: 0630 vs 0331

Quote:
Originally Posted by Dr. Dyno
Avoid the 0331 heads like the plague. Apart from the fact that the exhaust ports are tiny, these heads are crack prone especially between the 60,000-90,000 mile mark (outside the powertrain warranty period so basically you're screwed if it happens).

Actually, I believe there might be a recall on this one. A friend of mine bought a 01 used and with in the frist week of owner ship it started to overheat and go thru coolant like water on her. After some research here, I told her to take it back and they relaced the head free of charge. I am not sure how, shop warrenty or recall, but its definately worth a shot.


Oh yeah, the Dr is right on this one.........besides the low pinion front axle, extra cats........this is the other reason to stay away from the later 99's and newer.....if buying used.
Reply With Quote
  #10  
Old September 29th, 2006, 08:53
Root Moose's Avatar
Root Moose Root Moose is offline
NAXJA Forum User
 
Join Date: Jul 2003
Location: ON, Canada
Posts: 3,736
Re: 0630 vs 0331

Quote:
Originally Posted by CartsXJ
Actually, I believe there might be a recall on this one. A friend of mine bought a 01 used and with in the frist week of owner ship it started to overheat and go thru coolant like water on her. After some research here, I told her to take it back and they relaced the head free of charge. I am not sure how, shop warrenty or recall, but its definately worth a shot.
Likely shop recall. There has not been a recall on the 0331 and there likely will not be from what I read. There are two many 0331 castings that work fine.
Reply With Quote
  #11  
Old October 4th, 2006, 13:32
Rattman's Avatar
Rattman Rattman is offline
NAXJA Forum User
 
Join Date: Sep 2004
Location: Oklahoma City
Posts: 82
Re: 0630 vs 0331

I don't know if you read my other post on swaping the shafts out of the Low P 30 in to a HP 30, but to make a long story short my 92 was totaled by an idiot, and I know have a 01. I bought the 92 back from the Insurance company for 400 bucks. So I have the head on that engine, which I had a tri angle valve job and recessed valves instaled. How hard to swap it over, just the ignition rail Issue? Sounds Like a no brainer as far a quality and performance. Might be worth it just to get rid of that stupid child proof oil cap on the valve cover.
Reply With Quote
  #12  
Old October 4th, 2006, 13:41
rstarch345 rstarch345 is offline
NAXJA Forum User
 
Join Date: Apr 2005
Location: Where ever I can wheel
Posts: 761
Re: 0630 vs 0331

I just replaced my 0331 3 weeks ago before my Moab trip. No change im MPG but definately felt more low end torque. Changed out a few other items while I had everything down.

Fabbing up a couple of straps from the ign rail to the valve cover bolts didn't take much, so that wasn't a problem.

To me, it was a worthwhile swap as I was just beginning to notice issues that was pointing to the head. To bad DC didn't have the same foresight.
Reply With Quote
  #13  
Old October 4th, 2006, 13:57
Rattman's Avatar
Rattman Rattman is offline
NAXJA Forum User
 
Join Date: Sep 2004
Location: Oklahoma City
Posts: 82
Re: 0630 vs 0331

Which head did you use the 7120 or the 0630? Can you post a pick of your retrofit? I am sure I can figure out how to make the straps work, but it never hurts to see someone elses ideas.
Reply With Quote
  #14  
Old October 4th, 2006, 14:06
rstarch345 rstarch345 is offline
NAXJA Forum User
 
Join Date: Apr 2005
Location: Where ever I can wheel
Posts: 761
Re: 0630 vs 0331

Quote:
Originally Posted by Rattman
Which head did you use the 7120 or the 0630? Can you post a pick of your retrofit? I am sure I can figure out how to make the straps work, but it never hurts to see someone elses ideas.
Yup! I can either post up a pic tonight or in the A.M. sure. Family arriving from TN so depending on time.

When I dropped in the 0630 head, I did it with the intake/exhaust already mounted. A few people advised against it, but since I had a lift and extra muscle, it went down real smoothe. Glad I did it, 'cause getting to those manifold bolts was a PIA that I wasn't looking forward to.
Reply With Quote
  #15  
Old October 4th, 2006, 14:31
5-90's Avatar
5-90 5-90 is offline
NAXJA Forum User
 
Join Date: Mar 2003
Location: Hammerspace
Posts: 18,821
Re: 0630 vs 0331

Quote:
Originally Posted by rstarch345
Yup! I can either post up a pic tonight or in the A.M. sure. Family arriving from TN so depending on time.

When I dropped in the 0630 head, I did it with the intake/exhaust already mounted. A few people advised against it, but since I had a lift and extra muscle, it went down real smoothe. Glad I did it, 'cause getting to those manifold bolts was a PIA that I wasn't looking forward to.
Don't see why people would advise against it - I tend to advise people to do that, for the same reason you noted! It's a lot easier to service the manifold gasket on the bench than on the engine - by a couple orders of magnitude...

Granted, I'm a fairly large individual, and waving around a two-foot long iron casting isn't that big a deal for me, but if you're going to do the job and you don't have the power to do it yourself, get someone who can help you who can follow instructions immediately and accurately. Two extra hands helps - but they've got to be hooked to a single brain order to work...

5-90
Reply With Quote
Reply


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

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Poll: Cracked 0331 cylinder head castings Dr. Dyno OEM Tech Discussion 31 November 21st, 2012 18:52
0331 head replacement Ben H For Sale: Private Party Only. XJ ITEMS ONLY 2 January 25th, 2007 17:38
0331 head Identifing dyna OEM Tech Discussion 6 July 28th, 2006 18:47


All times are GMT -7. The time now is 07:04.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014