4.0 Cylinder Head Conversion on 258
The 258 or 4.2L Jeep Engine was designed by American Motors in the late 60’s and first put into Jeeps and AMC production cars in 1970. The 258 is the same block as the 232 with a crankshaft with a longer stroke. This longer crank is what makes the 258 a great motor for 4-Wheeling, because it provides low-end torque for rock crawling. But, sometimes we like to go up hills, pull trailers and pass other cars. The cylinder head on the 4.0-Liter Jeep engine will provide more horsepower to allow you to do some of these things. Match the 4.0L Head with the 258 block and now, you have the best of both. Domain: http://www.monsterslayer.com
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Submitted by kizer on 10/25/03 Edited
10/25/03
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4.0 head on a 4.2L block
In this article I am going to explain the basic fundamentals of a not-so-hard shadetree mechanic head conversion on a 4.2L 258ci engine block. As I'm sure any Jeeper knows, these are the engines that mainly came in the CJs and early YJs. After several months of research, I came upon some discoveries about putting a 4.0L head on a 4.2L block. Apparently the block on a 4.2L and 4.0L are very similar except the 4.2L has a longer stroke and a few design differences. After I sent several e-mails trying to find out more information about this conversion, I was informed that this conversion is possible and can provide a 40HP gain. That'&s right, 40HP! I was a little surprised myself. Not only does this conversion add more HP, but I have read that people have experienced a substantial increase in gas mileage{semicolon} approx. 17-18%. Domain: http://www.off-road.com
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Submitted by kizer on 10/25/03 Edited
01/07/04
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4.0 Throttle Body
Well, for a while now, I'&ve been looking for something to put a little more umph back into the 4 Banger.. I had heard through a few sources that a Throttle Body from a 6 Cylinder (4.0) Jeep Wrangler (YJ after 91) or Cherokee (XJ after 87) will fit on the 2.5L engine without any modification and will give you some decent games for the money. Domain: http://tragedyeric.tripod.com
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Submitted by jeeperchris on 10/24/03 Edited
10/24/03
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4.0 Throttle Body for your 2.5L
We're willing to bet that if you have a 2.5L YJ, you're looking for some more ponies under your hood. If you've installed larger tires and haven't changed the gears yet, you probably haven't seen 5th gear in a while. Just getting the Jeep to move require feathering the clutch more then you really want to. If that's you then you will want to read on..... Domain: http://www.4x4wire.com
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Submitted by jeeperchris on 10/10/03 Edited
01/09/04
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4.2 LITER (258 CID) Multipoint fuel injection kit
Installing a multipoint fuel injection kit on a 4.2 engine Domain: http://www.visi.com
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Submitted by kizer on 10/25/03
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5 ways to fix a radiator leak on the trail
For those of you that do their 4-wheeling in some remote area or in some vegetated sections that typically have tree limbs that poke out, we comprised this list of a few simple tricks that can fix a radiator leak (a small one) with out having to carry a spare radiator with you. Domain: http://www.4x4review.com
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Submitted by themajor on 06/19/04
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5.7-liter HEMI Specs and Features
Specifications and features of the new 5.7-liter HEMI engine. This engine will be used in the 2005 Jeep Grand Cherokee Domain: http://jeephorizons.com
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Submitted by Code3TJ on 07/10/04
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Aluminum Valve Cover
Most stock 258 motors with the plastic valve covers have a common problem with warped valve covers that leak oil. The oil leak problem is not because the plastic valve cover can't withstand the heat in the engine bay, it's usually because the plastic cover wasn't installed properly. The plastic valve cover's efficiency is compromised if there is uneven torque on the bolts, or if some of the bolts were tightened before all the bolts were installed. In either case, it will eventually result in a warped cover. Eventually, a new gasket and/or tons of silicon will no longer work and a new cover will be necessary. Domain: http://www.sierrajeep.com
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Submitted by Code3TJ on 08/30/04
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Auxiliary Cooling – Hood Vents
Hi Folks, this will be the first of at least two, possibly three write-ups on my efforts to better manage under hood temperatures. This one will be on Hood Louvers and my thinking, testing and implementation on my 97 TJ Wrangler with the 4.0L 6Cyl Engine.
This write up on Hood Vents is in two parts:
The theory and testing of the hood vents The installation of the hood vents Domain: http://www.oman4x4.com
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by a guest on 10/31/03 Edited
02/02/04
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Auxiliary Cooling – Oil to Coolant Coolers
Detailed info on installing various engine oil coolers including tracking of average and high coolant and oil temperatures before and after the installation. Domain: http://jeepsunlimited.com
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Submitted by Code3TJ on 08/21/04 Edited
08/21/04
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Boring the throttle body
I have read much about installing bored throttle bodies on the XJ, TJ, ZJ, etc ( they are all the same throttle body on the 4.0 six ), like on Jason's site and the one Turbo city sells among others and they give better response even more so after you have fitted free flowing exhaust. Most take your throttle body on an exchange bases where they sell ( ~$225 usd. ) you one that has already been bored out and you get a refund ( ~$125 usd. ) after you return yours. I don't have this option in Australia and found that all they do is remove the inward taper from below the butterfly so that it is the same diameter all the way through. Others had done this themselves with the same results so I thought I would do the same. I believe that the lip that you remove is to make taking off smoother as it effectively blocks one side of the butterfly off on the first few degrees of opening so the air only goes past the top side. It also explains why I felt the most change at small throttle Domain: http://go.jeep-xj.info
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Submitted by kizer on 11/14/03 Edited
01/07/04
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Broken Exhaust Manifold Stud Repair
Many times the intake / exhaust manifold bolts seem to be deficient in the strength to prevent their breakage when removing the manifold nuts. Knowing this I always heat the nuts prior to removing them. Well almost always. Below is how I repaired the situation when I skipped the heat the nut step. Domain: http://mightymo.org
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Submitted by Code3TJ on 07/11/04
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Carburetor Tech
How to identify and rebuild a Rochester Quadrajet carburetor. Domain: http://www.4wheelnoffroad.com
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Submitted by Code3TJ on 07/31/05
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Carter BBD carb fix
Terry L. Howe did a great article on the Carter BBD carb problem, however he didn't provide many pictures.
This an enhancement to his article that's full of photos. Domain: http://www.yellowjeep.org
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Submitted by RockDawg on 12/13/03
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