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0331 to 0630 Swap Kit

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NAXJA Member #955
NAXJA Member
As a result of my 0331 head cracking and all that stuff that we all know about, I made an adapter plate for myself so that I could use an 0630 head with my stock '01 exhaust system.
My Jeep - 2001 XJ Limited 4.0
My Exhaust - 2 cast manifolds w/ 2 pre-cats and 4 Oxygen sensors.

For those in doubt, if you have the 0331 head and the exhaust described above, your exhaust manifolds will absolutely NOT cover the exhaust ports in the 0630 head. I can't comment on other exhaust systems, but is suspect that if you're changing from any 0331 head and you have a stock exhaust, you are probably going to have an issue.

If you're like me, you don't want to replace the 0331 with another 0331, but you also don't want to replace your stock exhaust just because of the exhaust port issue in the 0630 head. This is why I made myself this adapter plate - to solve this problem. It gets sandwiched between the head and intake/exhaust to effectively block to portion of the 0630 exhaust ports that aren't covered by the stock exhaust. The stack-up goes like this:
0630 Head
0630 Intake Exhaust Gasket
Exhaust/Intake Adapter Plate
0331 Intake/Exhaust Gasket
Stock Intake and Exhaust Manifold

Also, the 0630 head doesn't have the standoff's to support the ignition rail. I bent up some aluminum brackets that support the rail from the valve cover studs. I'll sell those too if people want them.

$150 - 0630 Exhaust/Intake Adapter Plate
$25 - Ignition Rail Brackets with all mounting hardware. I can have these black anodized for additional cost if you're concerned about calling attention to them, or if you just want them to look cool. I'll have to check, but I think I can get it done for cheap money.

Neccessary Additional Parts to do the swap (meaning that you need to get these yourself)
- 0630 Head (duh)
- 0630 Head Gasket (I used OEM gasket from '98 XJ) - approx. $50
- 0630 Intake/Exhaust Gasket (I used OEM gasket from '98 XJ) - approx. $15

Kinda optional parts
- 0331 Intake/Exhaust Gasket (mine was okay so I re-used it, I'v been told not to do this though. Mine seems to be fine)
- Cylinder Head Bolts (I didn't bother - FSM says that they are okay to re-use once)
- Valve Cover Gasket (I replaced, but stuck with the re-usable kind from the 0331 head)
- Thermostat + Thermostat Gasket - approx. $7

Here's some other tips if you're starting with a junk yard 0630
- Take it to a machine shop, check for flatness, valve seat condition and cracks
- Valve Lapping Compound (if you didn't have the shop do a valve job and you're there anyway, you might as well lap them, I did)
- Valve Stem Seals - 6 intake + 6 exhuast (I used OEM from '98 XJ)

If you want a complete swap kit (including all/any of the OEM stuff), tack on $10 plus the OEM cost of the items you want, and I'll round it all up and send it in one kit for you. So the price will be $185 + OEM items.

Lastly - The only other thing (that I can think of right now) that you need to watch for is the Temp Sensor Plug - the 0630 head has a threaded hole near the firewall end of the casting for a coolant sensor (or something). Luckily for me, the head I used had the sensor busted off, but the threaded portion was still in the head, plugging the hole. So, I don't know what the thread is, but you still need to watch for this on yours.

Luckily for you, I'v been through this all now (mine went at 93K) and made a print of the adapter when I was making my plate. I even have some inventory of the parts ready to ship now.
Some addition "optional parts" you might want to think about
- Dowel pins from the block to head. There are two of them, not a bad idea to have on hand in case the existing ones get bend while removing the head.
- Dowel pins from head to intake. There are two of these as well. They will be pressed into the head, and it can be tough to pull them out without damaging them. Vice grips with a rag worked for me.

One other thing - On all orders, I'll pay for shipping costs, but only up to $10. This will get it from MA to CA with USPS normal shipping. I probably should have clarified this earlier.
pictures of plate:

The "threaded port" on the back of the #0630 head for the temperature sensor should be threaded 1/8"-27 NPT (as I recall,) so you can also just get a brass plug from the hardware store to close that hole off. Use some Teflon paste to ensure a good seal (or you can go ahead and use a sensor there to drive a gage, or just leave the OEM sensor in place if you don't mind doing that.)

Just an FYI...
update, i'm not making the coil rail brackets anymore. or doing the shopping on the rest of the stuff.

i'm selling just the adapter plate from now on.
I've lowered the price to $100 + shipping. (it's never been over $10 for standard ground)

Also, just so everyone knows, I have also been shipping the plate with some basic instructions. They include the torque specs and sequences for the head and the intake/exhaust bolts. I also put a bunch of other torque specs for this job in there, like for the valve cover.

I still find it shocking that this has happened to so many vehicles and corporate has done nothing. It's ridiculous.
Cost is $110 (this includes shipping to anywhere in the continental US)
I no longer carry these in stock.
You can e-mail me directly at [email protected] for an individual quote if you'd like, but the price will definately be more than $110. Probably around $150?
Please include your address in the PM so I can estimate shipping.
Sorry for inconvenience guys.
- Mike
I ordered more of these parts and have them in stock again.
Cost is $110 and includes standard ground shipping within the lower 48.
I figured I'd just add an FAQ. I seem to be selling quite a few of these lately and I get a lot of the same questions:

Question: Do I still sell these parts?
Answer: Yes. I only sell the adapter plates though. I keep some in stock at all times now and usually have stashed in my car so I can ship same day on short notice.

Question: How do I pay?
Answer: If you live within the lower 48 and USPS Priority Mail is okay with you, then just Paypal $110 to [email protected] and I'll ship when your payment clears. It usually takes between 1 and 3 days to arrive (depending on your distance from MA).
If you want special shipping, e-mail me at [email protected] for a quote and I'll supply you an exact cost. My zipcode is 02140 if you want to calculate your own expedited shipping. Just add $100 to the shipping estimate and that's your cost. USPS has thus far always the lowest cost method. The max package dimensions are 30.0" x 6.0" x 0.5" and it weighs 3 lbs. FYI - overnight is usually somewhere around $30.

Question: Will it work with a 7120 Head?
Answer: Yes. I haven't done this swap myself, but I have sold several at this point to other people that have successfully done it. No reported issues.

Question: Does it restrict flow?
Simple Answer: The plate itself must (to some degree) restrict flow. I think installing the 0630 head must have the opposite effect though.
Long Answer: I expected there would be a power loss after I installed the first plate on my own XJ. Surprisingly enough, there was no noticeable difference in HP when I did my own. Others have reported the same result. In fact, no one has reported a loss at all. So, my opinion is that the adapter and the 0630 head have pretty much the same net pressure drop as the 0331 head.
Yes - I'm still selling this plate! Maybe I should learn how to make a website for this thing?

Regarding performance: There honestly seems to be no noticeable loss in performance. Think about this - the clearance holes in this plate are pretty much the same size as your stock exhaust.
So unless you are replacing your stock headers for something that matches the 0630 ports (in which case you would definitely not be interested in the plate anyway) then this plate is not your limiting factor - it's your exhaust. I get this question a lot.
Hi Folks, 2 Updates:

1) I'm increasing the price to $120 (to cover increases in PayPal charges and shipping charges.), that still includes USPS Priority Shipping in the lower 48. I ship from 02140 (near Boston, MA), so depending on where you are, it's about 1 to 3 days (typically, it's 2 days).

2) Just an FYI - I typically have one packaged and ready to ship with me so that I can ship the same day that payment clears. Lately, that is almost always instant through PayPal, but does depend on the PayPal method you choose.
Yup - I still make these plates and have sold many of them to date. I think it has to be up around 60 or so by now. I get this question all the time. Still no issues reported back from any customers. I also now keep inventory on hand at all times and typically ship same day.

There's an official website now too - http://jeepexhaustadapter.com/
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