Head Bolt Torque for 4.0 Head Swap + other ? - 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 Wrangler Forums > YJ Wrangler Technical Forum > Head Bolt Torque for 4.0 Head Swap + other ?

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitThe Original 3/8" Ruffstuff Diff Cover!Building a Bumper?

Reply
Unread 06-11-2009, 08:41 PM   #1
nfisher50
Registered User
1987 YJ Wrangler 
 
Join Date: May 2006
Posts: 113
Head Bolt Torque for 4.0 Head Swap + other ?

Okay....almost all the forums say to torque the 4.0 head to the 4.2 block using the 110 ft-lb torque specs of the 4.0 head. But since you are really torqing into the 4.2 block, why would you not use the 85 ft-lbs as whats specified for the 4.2 head bolts?

Also, i've been trying to figure out pushrod length. it looks like using the 4.0 pushrods (9.640") is about 0.040" too long. Anyone else confirm this? If I had 9.600" I'd be between 0.020-0.040" of preload.

One more....I have a comp cam 252H grind. It is supposed to be mild, but not recommended for FI, which I'm converting too. Anyone know if this will really give me a problem?

nfisher50 is offline   Reply With Quote
Unread 06-11-2009, 11:32 PM   #2
4.7stroker
Registered User
1988 YJ Wrangler 
 
Join Date: Apr 2007
Location: Rio Rancho NM
Posts: 4,299
I went down that path and..............
I used the 4.0 tq specs, don't forget that one bolt where the tstat is has a lower tq spec.
I used the 4.0 pushrods with no problem.
I think the cam may cause tuning issues but I am carbed with that cam so I have no personal experience with that cam and FI.

Dwayne
4.7stroker is offline   Reply With Quote
Unread 06-12-2009, 09:37 AM   #3
nfisher50
Registered User
1987 YJ Wrangler 
 
Join Date: May 2006
Posts: 113
Thanks for the feedback....

so is everyone torquing the head to 110 ft-lbs. I guess it doesn't make sense when the haynes manual says 85 ft-lbs, unless it has something to do with the compression between the head and the block that is different from the 4.2 head?
nfisher50 is offline   Reply With Quote
Unread 06-12-2009, 10:32 AM   #4
Reverb
Registered User
1988 YJ Wrangler 
 
Join Date: Dec 2008
Location: NY
Posts: 600
I was told by Clearwater to use 258 push rods
Reverb is offline   Reply With Quote
Unread 06-12-2009, 10:55 AM   #5
nfisher50
Registered User
1987 YJ Wrangler 
 
Join Date: May 2006
Posts: 113
my reman 4.2 motor with head came with 9.744" pushrods, this gave me 0.120" excessive preload.
nfisher50 is offline   Reply With Quote
Unread 06-12-2009, 11:32 AM   #6
Reverb
Registered User
1988 YJ Wrangler 
 
Join Date: Dec 2008
Location: NY
Posts: 600
Quote:
Originally Posted by nfisher50 View Post
my reman 4.2 motor with head came with 9.744" pushrods, this gave me 0.120" excessive preload.
That's what I thought, so I emailed clearwater - I bought the head off them - and they told me to use my original push rods. Doesn't it depend on how much it's been skimmed? I always though you needed 60 thou taken off the head to use 4.0 push rods
Reverb is offline   Reply With Quote
Unread 06-12-2009, 11:42 AM   #7
Reverb
Registered User
1988 YJ Wrangler 
 
Join Date: Dec 2008
Location: NY
Posts: 600
On more thing - are the tappets the same on both engines?
Reverb is offline   Reply With Quote
Unread 06-12-2009, 11:56 AM   #8
4.7stroker
Registered User
1988 YJ Wrangler 
 
Join Date: Apr 2007
Location: Rio Rancho NM
Posts: 4,299
Yes the rockers are the same.

Dwayne
4.7stroker is offline   Reply With Quote
Unread 06-12-2009, 12:49 PM   #9
nfisher50
Registered User
1987 YJ Wrangler 
 
Join Date: May 2006
Posts: 113
what I think I'll end up doing is using the 4.0 pushrods since these measured 9.640 and then use 0.040" spacers to get my preload back withn 0.020" plus or minus 0.010" as recommended by comp cams. The 4.0 head was true and therefore I didn't have to get it decked. I'm surprised in all that I've read on this head swap, not much talk has been on the proper pushrod length.

I got my reman motor from jasper with the comp cam 252H grind installed and they installed 9.744 long pushrods which were waayy too long. I could never get it tuned with the weber cam and I'm wondering if this is why. I bet I never got a valve to completely seat!

Anyone have any more info on the proper torque values of the head bolts? I'm still reading on the net to torque to the 4.0 head spec. I have the 1/2" head bolts.
nfisher50 is offline   Reply With Quote
Unread 06-12-2009, 01:03 PM   #10
88YJtoCJ
Registered User
1988 YJ Wrangler 
 
Join Date: May 2009
Location: Sarasota, FL
Posts: 260
never trust the haynes manual on torque specs they can be wrong... Ask me how I know...
88YJtoCJ is offline   Reply With Quote
Unread 06-13-2009, 05:53 PM   #11
Reverb
Registered User
1988 YJ Wrangler 
 
Join Date: Dec 2008
Location: NY
Posts: 600
Has anyone who's done the swap ever run into any problems with 4.2 rods?
Reverb is offline   Reply With Quote
Unread 06-13-2009, 10:57 PM   #12
Douglas S.
Registered User
1991  
 
Join Date: Jun 2007
Location: Saskatchewan, Canada
Posts: 2,645
Nope..........
__________________
1991 Land Cruiser HDJ81
1987 YJ Laredo
Douglas S. is offline   Reply With Quote
Unread 06-15-2009, 03:08 PM   #13
nickdestfino
Registered User
1989 YJ Wrangler 
 
Join Date: Jul 2008
Location: sacramento
Posts: 129
Hey bro. I used the clearwater head 7120 casting stock 4.2 push rods and rockers. headbolt torque was 85 ft lbs. I'm also running the same cam I think comp cam 451 480 lift something like that with 91-95 fuel injection man. 63 mm. throttle body, bosch design 3 injector with the 93 harness and 368 ecm. I couldn't be happier with this set up. Has all the torque in the world.. Did the rubicon this last weekend on 35's 456's motor never revved over 800 rpm (sober) and never got over 200 degrees. My short block had almost 200K before doing the cam heads and injection. My compression was around 170 or so per cylinder so I went for it........I passed ca. emissions with this set up as well.
__________________
I need to go to Jeeps anonymous, I think I have a problem
nickdestfino is offline   Reply With Quote
Unread 06-15-2009, 03:17 PM   #14
nickdestfino
Registered User
1989 YJ Wrangler 
 
Join Date: Jul 2008
Location: sacramento
Posts: 129
dont forget to replace lifters when you do the cam. I rushed mine and had a lifter collapse. Had to grind the the rocker pedestal on the head down to quiet the tapping(non adjustable rockers). The new head was in transit at the time and I had to go to work the next day. I drove it like the next 3 weeks like that with out problems. You can't hurt these motors they only get better. Also you should order the valve lash shim kit that hesco sells to get your adjustment nutz.
__________________
I need to go to Jeeps anonymous, I think I have a problem
nickdestfino is offline   Reply With Quote
Unread 10-01-2010, 09:48 AM   #15
MMPSM
Registered User
1959 CJ6 
 
Join Date: Apr 2010
Location: Estes Park, CO
Posts: 83
Yes! I ended up using Cherokee 2.5 rods. (9.485?). Now I have a rubbing noise when engine is at temp. The 258 rods gave me preload of 0.125. Torquing original 258 rods to spec, (19 to 21#, depending on who you trust), made all valves open all the time. Needless to say the engine will not run with all valves open all the time.

I researched this project for a year, read many articles and interviewed a guy that had done it. All, ALL said reuse the 258 rods.

MMSM
MMPSM 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.