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Unread 01-27-2011, 08:13 AM   #16
fredrok
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Clearwater Cyl. heads has one of the best bangs for the buck. However, they need a lesson on cleanliness as I felt the need to disassemble it, wash, lube and reassemble. I have the tools, the know how and I ran a race engine machine shop, so I'm also a bit for anal than most. Guess it wouldn't make a grand difference.

Welding the ports is the correct way to go. In the end, I went with a different valve spring,retainer and keepers due to a cam change but most don't need to concern themselves with that. Add a Felpro head gasket, pushrods, centering washers (if you have 7/16" bolts) and whatever $90 valve cover you like and you're set for under $800.

There are a bunch on stealBay now for $400-$500 range it seems. However, you certainly can't go wrong with Hesco either. Their support is great.

You will need a 4.0 intake (the MPI kit comes with that) and order a header for an early YJ 4.0. I happen to use the Borla.

Here's some more 4.0 head info:
The stock cylinder head is cast iron and weighs 60lb. The valve head diameter is 1.91" intake/1.50" exhaust. Casting numbers are as follows:

Year............Casting No
1987-90......2686
1991-95......7120
1996-99......0630
2000-01......0331

Cylinder head flow figures (cfm) at 25inH2O pressure drop are:

Non-HO head #2686

Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 122.0 168.0 186.0 189.0 192.0
Exhaust flow....88.0 114.0 130.0 134.0 138.0

Ported non-HO head #2686

Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 124.0 183.0 197.0 207.0 216.0
Exhaust flow....87.0 113.0 138.0 153.0 159.0

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-'99 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '00 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.
The intake ports of the HO head are rectangular and measure 1.625" x 1.375", while the exhaust ports are elliptical and measure only 1.375" x 1.250". The port cross-sectional areas are 2.234 and 1.350 sq. inches respectively. For good street performance, it is recommended that the port c/s area should be about 85% of the valve head area. Therefore it should be 2.435 sq. in. for the intake ports and 1.502 sq. in. for the exhaust ports. The stock port c/s areas therefore need to be enlarged by 9.0% for the intake and 11.3% for the exhaust. The ports should be matched to the intake and exhaust manifold runners to smoothen airflow and prevent power-robbing turbulence.



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Unread 02-01-2011, 02:58 PM   #17
WillyC24
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This may be a noob question, but I'm beginning to understand that following the 4.0 head conversion with a correctly sealed head (sealing the water/coolant ports), that I won't have the ability to wire the temp sensor gauge. Is this correct? Apologies if this is a foolish question.
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Unread 02-01-2011, 04:49 PM   #18
james04si
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if you get the 7120 casting head you will still have the coolant temp hole at the rear of the head just like the 258 head has. All others 4.0 castings do not have this coolant hole drilled on the head.
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Unread 02-01-2011, 05:51 PM   #19
razor2264
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I just recieved my 7120 cylinder head from clearwater. I am installing clifford valves, springs, cam, intake, exhaust, along with the 4.0 head on my 258. I took the clearwater head to my local machine shop to get the larger clifford intake valves installed along with the larger springs. they pressure tested the valve seats and the results werent what i would have hoped for. I think cleawater is okay but take the head to a shop and get it checked before you bolt it up on your jeep.
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Unread 02-01-2011, 09:21 PM   #20
johnson30
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Coolant probe

I'm basically echoing james04, just from my experience: the Hesco head I got, which I guess had to be the 7120, had an allen head stud in the coolant hole in the same spot as the 258 head.

When I swapped heads, I took the probe out of the 258 head, removed the allen head stud from the 242 head, and traded them out. The wire plugs in just like it did with the 258 head.

-----------------

Now, not to confuse things, but I have a question- isnt there a temp probe/ sender on the 4.2 intake? I thought there was, but when I did this swap (before doing what I described above), I tried to plug into what looked like the temp probe on the back of the intake. There are two, one is in the front, which I'm pretty confident is the knock sensor, but the back one should be a temp sender- problem is, when I plugged it in, my temp needle pegged. Yikes. Am I wrong, or is my intake temp sender busted? Not that I need it.....
intake-mod.jpg  
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Unread 02-01-2011, 10:32 PM   #21
VACJ7
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Quote:
Originally Posted by johnson30 View Post
Now, not to confuse things, but I have a question- isnt there a temp probe/ sender on the 4.2 intake? I thought there was, but when I did this swap (before doing what I described above), I tried to plug into what looked like the temp probe on the back of the intake. There are two, one is in the front, which I'm pretty confident is the knock sensor, but the back one should be a temp sender- problem is, when I plugged it in, my temp needle pegged. Yikes. Am I wrong, or is my intake temp sender busted? Not that I need it.....
The one you have marked as temp probe is a temp switch. It triggers the manifold heater to turn off when the coolant reaches a set temp.
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Unread 02-02-2011, 01:07 AM   #22
johnson30
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Ah-ha.

OK, that makes sense then why it immediately pegged the temp gauge: it was grounded when the coolant was cold, and would have switched off when the temp reached 160 deg.

So my next question is: what is the pigtail hanging off the forward temp switch for? I'm guessing this has to be for the electric choke? I have my choke wired directly to a switched 12V source to turn on immediately. After about 20 seconds of running, the choke plate is open and I'm running at normal idle. Shame on me, though, for having it wired so that when the ignition is in the on (not run) position, the e-choke is getting power. Really, that won't be an issue soon because of phase 2 in this buildup:

I'm switching to a TBI, so the pigtail is going to be gone soon, replaced by the Howell temp sensor, but I'm going to need to wire up the intake heater eventually. From what I've gathered, I'll need the oil pressure sending unit to send 12V to the heater relay, and that same signal will get grounded by the temp switch on the back of the intake. A constant 12V source will provide the actual power to the heater when the relay is getting power by way of the oil pressure switch and is concurrently grounded by the temp switch, which will turn the heater off if no oil pressure (engine off or cranking) and when the coolant temp reaches 160.

Ok, that makes a lot of sense. I hope I got it right.
intake-mod.jpg  
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Unread 04-07-2011, 03:16 PM   #23
WillyC24
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My engine rebuild shop has quoted $2100 for a complete tear-down and long-block build, including dyno, for my 4.0 head swap and complete Clifford rebuild kit.

This is a complete job -- they helped me get it out of the Jeep and are going to fully test, balance, re-torque, and break-in my new engine over several days on the dyno.

Is this a fair deal?
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Unread 04-07-2011, 06:59 PM   #24
captkhaos
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I saw a Service Bulletin at the head (cylinder) shop the other day warning about weakness in the O331 casting. The guy told me they crack and need to be welded. I'd stay away from them. He had one come in (I saw it) that had already been welded once.
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Unread 04-10-2011, 02:15 PM   #25
WillyC24
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Now my engine shop has shown me more detail about my Clearwater 4.0L head I recently bought to put on my 4.2L...

Between two of the valve cylinders is a considerably large weld area, which it appears fixed a previous deep crack.

You can find photos of this at:





My concern is that in some unknown time, due to differences in heat transfer between the engine block and weld, my new cylinder head will suffer the same fate it apparently experienced beforehand. This could cause some catastrophic failure of my newly rebuilt engine, and destroy other new parts within in. I understand that Clearwater's description states that remanufactured product defects have been "rectified" and pressure tested, but I'm a bit uneasy about this head given the severity and critical location of the previous fracture.

Does someone have experience with this type of welding on reman heads? Should I demand an exchange for a different head?
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Unread 04-10-2011, 03:33 PM   #26
fredrok
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I would not worry about it. Yet, I have a Clearwater head and I'm not exactly a big fan. I found it necessary to disassemble it and clean it and the valvetrain to a better standard than what they had done. I lapped the valves to check their grinding work and was pretty pleased with it.

Cast iron is more brazing really than "welding" but when done correctly, will usually not pose any issues down the road. And especially not on low horsepower-low compression engines as ours. In many welds/brazing you'll see pockets like in your pictures and unless they extend into another void, are harmless. When I ran a machine shop, we welded many aluminum and brazed many a cast iron product and I don't recall a single issue with any of them to follow. All of our stuff was race only.(Except for my 258 and occasional "friend job)

I would think that a high volume facility such as theirs would have that process and the subsequent testing to follow down pat.
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Unread 04-13-2011, 11:36 AM   #27
WillyC24
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Fredrok, thanks for the response. I had my shop re-pressure test the head and was assured by Clearwater that this weld is acceptable. Here goes hoping that the head doesn't blow at that critical point and my engine explode into a million teeny pieces.

Purchased the last parts necessary, some Harland Sharp roller rockers and hope to have the engine back soon!
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Unread 04-13-2011, 01:13 PM   #28
Chuckles0227
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i got a 7120 completely machined with valves for 264 plus shipping on ebay, when i test fit it i had no water jacket overlap so i didn't fill them and its been leak free for 2000 miles.

heres the link http://cgi.ebay.com/ebaymotors/ws/eB...#ht_2132wt_489
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Unread 04-14-2011, 06:39 AM   #29
gmakra
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Willlyc24 Who at Clifford is doing the work? If its Bob Goodwin you have hit pay dirt he is the most through engine builder I have ever met.

He did my stroker and he wont let it leave the shop till its absolutly perfect.
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Unread 04-19-2011, 08:19 AM   #30
WillyC24
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An engine shop here in Dallas is doing the work, Kim Barr Racing Engines. I've got high hopes for them, and will let you all know how it goes for future recommendations....
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