• Hello Guest, we are proud to now have our Wiki online that is completely compiled and written by our members. Feel free to browse our Jeep-CJ Wiki or click on any orange keyword when looking at posts in the forum.
    To dismiss this notice
    click the top right X.

4.2 motor build

4.2 motor build
So here is the build list
1996 jeep 4.0 head casting number 0630
Block 0 decked
Bored 0.030 new pistons
Comp cam 68-AMC 232 i6 -4
Crower 66031x-12 camsaver hydraulic lifters
P5249464 mopar valve springs
P4529218 mopar valve locks
P4452032 mopar valve spring retainers
High flow valves don't remember the brand
Clevlite .010 rod and crank bearings
Melling oil pump
Cloyes true roller timing chain/gears
Remained water pump
Howells chip for engine combo
Might be forgetting something
 
Block head bolts drilled 1/2 and tapped
Head decked .010
Stock AMC 258 i6 / 4.2l intake
Stock style 4.0 exhaust manifold
 
:popcorn:Now just waiting for dyno number when you get around to it!:drool:
 
1986cj7 said:
:popcorn:Now just waiting for dyno number when you get around to it!:drool:
Click to expand...

When I get 3000 miles on her I will put it on the dyno. The way I drive it should only be 2 months or so. :D
 
Sorry it's been so long sense I've posted on this thread. I have not update right now. Ran into personal problems so I haven't been able to drive my jeep.
 
Ok question for all you guys what size exhaust do you think I should use with this motor? I'm going with a flow master 40 series can't decide between 2 1/2 or 2 1/4
 
I dont have any opinion , just glad to get a notification this thread is alive. :)

Hope all is well


Me
 
I have always liked 2 1/2 myself. Have used it on almost every vehicle I've owned.


Sent from my iPhone using Tapatalk
 
I'm going 2.5" on mine .... not for any real performance reason ??
I googled best exhaust size for AMC 258 i6 / 4.2l hoping for a bit of performance write up but didn't find anything ...
I didn't really look that hard and settled with 2.5 :dunno:
 
A AMC 258 i6 / 4.2l really doesn't need any more than 2-1/4" but 2-1/2" looks cool so why not?

The only draw back I can think of is if you're running a 4.0 head with a tubular manifold. The down pipe clearance for the clutch linkage is already a little tight, especially if you run a hydraulic clutch. The slave cylinder will really close.
 
Hope this thread stays going. I'm getting ready to do the same build without FI. Talked to Comp and decided on the 68-231-4 cam with 462 Edition /485 intake and exaust lift. Odessa is making a head to compensate that lift now. Do I need longer rods? Anything else between the cam and valves/springs that I need to worry about or check?
 
Gsmithl10 said:
Hope this thread stays going. I'm getting ready to do the same build without FI. Talked to Comp and decided on the 68-231-4 cam with 462 Edition /485 intake and exaust lift. Odessa is making a head to compensate that lift now. Do I need longer rods? Anything else between the cam and valves/springs that I need to worry about or check?
Click to expand...

The push rods may need to be longer. Mine were too short. You will need to measure after building the motor. You want about .070" preload on the lifters. A little more or less won't hurt. Different length push rods were made for each year. You can order them from Napa or most parts stores.
 
rlitavecz said:
The push rods may need to be longer. Mine were too short. You will need to measure after building the motor. You want about .070" preload on the lifters. A little more or less won't hurt. Different length push rods were made for each year. You can order them from Napa or most parts stores.
Click to expand...


Buy the adjustable push rods. Set your preload with those then pull them out and take the measurement. Then you can buy the proper length the first time around.
 
Gsmithl10 said:
Hope this thread stays going. I'm getting ready to do the same build without FI. Talked to Comp and decided on the 68-231-4 cam with 462 Edition /485 intake and exaust lift. Odessa is making a head to compensate that lift now. Do I need longer rods? Anything else between the cam and valves/springs that I need to worry about or check?
Click to expand...
If your getting a comp cam don't get the whole kit the springs won't fit. I think somewhere in this thread are part # for morpar springs that will fit. It's been a while since I've read the whole thread. I've read it a few times because I'm in the process of building my AMC 258 i6 / 4.2l also.
 
rlitavecz said:
The push rods may need to be longer. Mine were too short. You will need to measure after building the motor. You want about .070" preload on the lifters. A little more or less won't hurt. Different length push rods were made for each year. You can order them from Napa or most parts stores.
Click to expand...


This will be the first time I've rebuild an engine or head so forgive the dumb question, but you got to start somewhere.:o What is .070 preload on the lifters and how do you set it?
 
Your rocker arms are non-adjustable. You torque the bolt down and leave it. The only way to set preload is by using the proper length push rods. To figure this length out try this:

Once the head is bolted in place, install two of your existing push rods. Just pick a cylinder. Now install the rocker arms and bridges, but don't tighten them all of the way down. Leave them about 1-1/2 to 2 turns loose. Now tighten each one slowly as you wiggle the push rod up and down. When it stops moving you have zero preload. Place a dial indicator on the arm above the push rod and measure how much it moves as you finish tightening the rocker arm nuts. That is the existing preload. Add or subtract the amount from the length of your push rod to obtain .070". That is the length of push rod you need to order.

Example: if your rocker only moved .010" before becoming tight, add .060" to your existing push rod length.
 
OK guys im hoping in the next few weeks i will have more info for you on how this motor runs. Stay tuned the thread isnt dead!!!
 
Its about time! Thought you sold the old girl! :laugh: j/k bud! Lets get her fired up!

:chug:
Jr
 
Installed a 2 1/4 inch exhaust with a flow master series 40 :D sounds really good.
 
You must log in or register to reply here.

Jeep-CJ Donation Drive

Help support Jeep-CJ.com by making a contribution.

Help support Jeep-CJ.com by making a contribution.
Goal
$200.00
Earned
$40.00
This donation drive ends in
0 hours, 0 minutes, 0 seconds
  20.0%
Contribute
Back
Top Bottom