Joshpit's 4.0 Swap Article
By AMC Eagle Nest Member Joshpit
She will ask for knobby tires.
A complete Walkthrough for swapping a 4.0 into an AMC Eagle
By: Joshua Tulberg
[email protected]Here is the printable pdf version:
http://www.amceaglenest.com/images/PDFS/Joshs%204.0%20Walkthrough.pdf
Starting Info:
I did this swap with my 1981 AMC Eagle SX4. The Eagle originally came with the 4.2 Liter straight 6.
My donor motor was a 1999 Jeep Cherokee 4.0 Liter
Because it was a 1999 4.0 Liter, the following walkthrough can be used for anyone swapping a 1996 or newer 4.0 Liter. The reason being:
Pre 1996 is Renix and OBDI Anything 1996 or newer is OBDII (mine)
When You Pull The Motor:
Make sure it does not have a security system… to do this you will need to call a local dealer and give them the vin number of the donor vehicle the 4.0 L is coming out of. With this number, the dealer will be able to tell you whether or not the vehicle came with the security system. If it has the security system, then you might as well give up on that wiring harness. If it does NOT have the security system, then you are good to go. You know you have a security system when you go to fire it up and it runs great for 3 seconds. (Ask me how I know) haha.
Make sure to get:
• The ENTIRE wiring harness that came with your 4.0 (do not cut any wires off of the harness, only disconnect the connectors) Some of the connectors are under the dash, so make sure not to just HACK away the harness from the engine compartment • The Fuse box that is inside the engine compartment • The Starter motor • The PCM (computer) • The intake and exhaust header • And all other sensors on the intake and also the O2 Sensor on the header • The C.P.S. (crankshaft position sensor) located on the bell-housing
- Note: Some people do a complete swap of drivelines: Engine, Tranny, and Transfer Case. By doing this you eliminate the problem of having to mount your C.P.S. to the 998 (Eagle) tranny and you also get the desired LOW range. However, you will need to shorten/lengthen the Eagles drive shafts due to the differing lengths of the 998 tranny and the donor vehicle’s tranny. There is also a good chance that the transfer case off of the donor vehicle has an “open” 4WD. You would be better off with a 229 transfer case that has a “viscous coupling”.
The Things They Don’t Tell You:
A lot of the information on the 4.0 Swap is found AFTER you’re half way into it…
• The Flex Plate:
If you pull your OBDII 4.0 L motor and are planning on attaching your Eagle’s 998 tranny to it, then you will most likely need a different flex plate than what the 4.0 came with.
What you will need is a 32RH/42RE Flex Plate. These flex plates came in 1991-1995 4.0 L Wranglers and late 1993-1996 4.0 L Grand Cherokees
• The Starter Motor:
The Eagle’s starter will not work with the new flew plate so make sure to get the new one off of the 4.0 donor
• The C.P.S.:
A sensor that requires some fabricating or 300 dollars to get it to work with your 998 Transmission.
• Expense:
Be prepared to spend a lot of money… just to give you an idea of how much… the fuel line alone will cost you approx 60 bucks.
• The Oil Pan:
You will need the oil pan off of your 4.2 because the one on the 4.0 will not clear the front axle (unless you have a strait axle already installed in your eagle)
FUEL:
• The Fuel Pump:
Because the 4.0 L is fuel injected you will need a fuel pump that is capable of at least 50 P.S.I.
I bought the most common pump: The “E2000” which is rated at 100 P.S.I.
Any in-line fuel pump capable of at least 50 P.S.I. should work fine. However, like many of the high-pressure in-line fuel pumps (E2000 included) they do not work well self priming. Meaning, if you ever run the tank out of gas it can be a royal to get the fuel to start pumping again.
A simple solution to this problem is mounting a self-priming in-line fuel pump that is rated for low pressure carbureted systems right before the high pressure pump. This will insure that the high pressure pump is always getting fuel.
I personally do not have a self-priming pump; I just mounted my E2000 at the same level as my gas tank and hoped for the best. I can drive till about 1/8 tank before I can hear my pump sucking air. I also get irregular “surging” during acceleration every once in a while, which I think is due to the fact that I don’t have a self-priming pump before my E2000.
• The Fuel Regulator:
OBDII 4.0’s require 49.5 P.S.I. of fuel pressure. The E2000 (and many other in-line pumps) dice out well over the 49.5 P.S.I. Therefore, you will need to regulate that pressure down to the 49.5 needed.
Some 4.0 L come with the fuel pressure regulator right on the fuel rail itself, so go check to see if you have one on the rail first.
If so, then that is one less thing you have to buy.
I didn’t have the regulator on the fuel rail so I went to my local dealership and asked them for the in-line fuel pressure regulator off of a Grand Cherokee. It cost me about 100 bucks.
• The Fuel Line:
Now that you have high pressure fuel you will need to replace your existing fuel line with fuel line rated for high pressure.
I bought two of the longest metal lines that my auto parts store carried and that took me a majority of the distance.
I then bought high pressure rubber fuel line to connect the gaps between the metal fuel lines and the pump/regulator/filter/fuel rail. This stuff is very expensive, so try to get a good estimate beforehand.
• The Fuel Filter:
Everyone has their own opinion on were and how to filter their gas, so this is how I did it:
I ran a low pressure (typical carbureted) fuel filter right BEFORE the high pressure pump. This keeps my pump from getting clogged and does the job of filtering. Not to mention it is a heck of a lot cheaper than a high pressure fuel filter.
The in-line fuel regulator that I bought also acts as a fuel filter, even though the fuel has already been filtered before the pump. It is not necessary to have a filter after the pump; it just turned out to be that way when I found out my regulator was also a filter.
• The Order:
This is MY order, and this order WORKS: (From the Eagle’s tank to the 4.0 L’s fuel rail)
TANK
Low Pressure Rubber Fuel Line
Low Pressure Fuel Filter
E2000 Fuel Pump (aka In-Line High Pressure Fuel Pump)
High Pressure Rubber Fuel Line
In-Line Fuel Regulator
High Pressure Rubber Fuel Line
Metal Tube Fuel Line
High Pressure Rubber Fuel Line
FUEL RAIL
