All the Other Little Things...
If only the project consisted of just the big, easy-to-grasp chunks
that have been covered in the previous sections, maybe this swap would've
taken less than almost a whole year. Unfortunately, it's never like
that. In reality, there's a whole bunch of little things that connect
all the big things together; no end of minor details that have to be figured
out and dealt with before the swap could actually begin. Here's the
list, in no particular order:
Retrofitting an
electric fuel pump and EFI tank
Rather than take a chance that a late-model YJ fuel pump would have the
pressure and flow capacities that the 5.0L engine needs, I installed an
stock-equivalent aftermarket 5.0L pump into a pump/sender bracket from
a mid-90's YJ. This took a little creative "adaptation" of the YJ
bracket, since the V8 pump is actually a lot smaller in size than the YJ
I6 pump - go figure. It turns out that the pump intake hole fits
through the bottom of the YJ bracket, and the factory pickup screen can
be installed on the other side no problem. I did find that the screen
I got with the new aftermarket pump did not fit as well. After the
4-6" of flexible line from the pump to the top of the bracket is installed,
the pump is held in place plenty well enough. The power and ground
wires from the YJ bracket fit onto the pump's terminals perfectly, and
the hose size was the same as well.
Here's a picture of the finished pump and bracket:
When Chrysler went to EFI on the YJ in 1991, they not only added a fuel
pump, but they changed the tank slightly as well. The 91+ tanks have
a small plastic baffle thing attached to the bottom of the tank, that cups
the pickup screen. My understanding is that this baffle acts like
a temporary fuel reservoir, making sure that the pickup is always submerged
in fuel, even when the Jeep is on an angle and there's not much in the
tank. I swapped out the tank in my '89 with one from a '93, since
I couldn't see a way to remove or retrofit the baffle.
I did have to play around a bit with the overall length of the pump
bracket, since the screen seems to stick down further than it did with
the YJ pump. I added a second rubber gasket between the pump mounting
flange and the tank, and that seemed to do the trick.
Installing a
fuel filter and 3/8" fuel supply line
To go along with the Mustang pump, it made sense to use a factory fuel
filter. These parts were designed to be used together, and not knowing
the pressure and flow ratings for any of these components, I wasn't inclined
to mix and match them. The Mustang uses a very simple, easily adaptable
mounting bracket, so I incorporated it with the filter. After looking
at a few mounting options, it seemed easiest to mount the filter and bracket
onto the front face of the gas tank skid plate. Here's a picture
of the mounted filter:
Also in the picture you can see the pieces of flexible high-pressure
fuel line I used to connect the filter to the pump and to the hard line
running along the driver's-side frame rail to the motor. Both ends
of every piece of flexible line were secured with twin EFI hose clamps.
These are special clamps made for specific sizes of line, and specifically
for high pressure EFI systems. They don't pinch the line, like gear-type
clamps can. The ones I used are Tridon p/n FI-6.
In the interest of preventing vapour-lock, I left the hard lines in
the factory location on that side, opposite from the exhaust. The
downside to this approach is that the 302 fuel rail feed and return lines
are on the right side of the engine, so I had to run sections of flexible
line from the front ends of the hard lines on the left frame rail, hang
them under the engine, and then connect them to the fuel rail quick-connects.
To make sure the 5.0L got all the gas it could guzzle, I replaced the
factory 5/16" supply hard line with 3/8" line. With the old powertrain
removed, it was pretty easy to bend up some new bulk steel line to match
the old one. A tubing bender and flaring tool came in handy - I put
mild flares on each end of the hard line to help keep the flexible lines
from sliding off, once the hose clamps were in place.
Motor Mounts
Before I get into the motor mounts, let me say that they are my least favourite
part of the new powertrain setup. My original plan was to use some
home-brew mounts on top of the original 258 frame mounts. Once the
engine was lowered into place, it quickly became apparent that this wouldn't
work - the exhaust manifolds cleared the motor mount brackets by no more
than half an inch. So, faced with having to come up with a solution
that didn't require a welder or large amounts of cutting, here's what I
ended up with:
It's not pretty, but it'll hold until I come up with something better in
the spring. In hindsight, it would have been better to grind off
the factory mounts altogether, and weld on some new mounts a bit further
back and several inches lower down.
For any CJ owners out there who are contemplating this swap, the motor
mount problem can be solved much more elegantly on your case, since the
CJ motor mounts bolt right to the frame instead of using welded-on brackets
like the YJ. Just replace the driver's side motor mount with a second
passenger-side mount, and the engine can be bolted to them without much
trouble.
Tranny/tcase mount and skidplate
In one of those rare strokes of luck that sometimes accompanies projects
like this, once the engine was locked into place and the gearboxes were
test-fit in situ for the first time, I found that the adapter between my
t-cases ended up right over the central rib in the factory YJ skidplate.
That, plus the fact that it still proved physically possible to install
the skidplate under the new powertrain, led to the design of this skidplate
mount:
I deliberately didn't design this mount until after everything was in place,
since there wasn't any way to accurately measure exactly where everything
would end up. So the mount was designed against the angles of the
sides of the adapter, it was welded together, and the appropriate angled
holes were drilled into the body of the adapter. The rubber pucks
are factory tranny mounts from the same Early Bronco that the D20 came
from, trimmed to clear the NP203 on the far side of the adapter.
The nice thing about this design is that it provides the same anti-rotational
effect as the torque arm on the factory YJ tranny mount, as well as being
a support for the rear half of the powertrain.
Right now only the two factory mounting holes in the skidplate are used.
I will be adding one more bolt on each end of the mount, as well as drain
holes for the two mount struts.
Fitting the transmission
shifter
One somewhat unfortunate side effect of swapping in a shorter engine and
a shorter tranny is that the tranny shifter ends up being a lot
further forward than before. The Ford pickups and Broncos that used
the 302 and NP435s (or T18s) needed very aggressively-bent tranny shifters
to clear the dashboards, and my YJ now needed something similar.
A little judicious application of Larry's torch was all that was required
to persuade the NP435's shifter that it would fit in the Jeep, and some
more gentle persuasion with my electric grinder convinced the Jeep's transmission
tunnel that it would accommodate the top cover of the NP435 poking through
it:
In first gear, the shifter clears the dash with just enough distance that
I don't smack my knuckles into it. It does hit the top of the center
console in reverse though, but is well enough engaged in gear at that point
that there's no problem. The other three gears have shorter throws,
so there's no interference problems there.
Transfer case shifters
I haven't installed shifters for the transfer cases yet, but I do plan
on doing this before the first snowfall, so I can get in and out of 4wd
without having to lock and unlock my hubs all the time. The NP203
shifter will use a conveniently located pivot hole cast into the right
side of the NP435, and a modified D20/D21 shift lever, with a home-made
linkage rod between the shifter and the shift cam (or whatever it's called)
on the NP203.
The D20 twin sticks will be made from some modified D18 factory twin
sticks, assuming they can be modified to work. A pivot point will
be created using some flat plate attached to the PTO port bolts on the
left side of the NP203 reduction box. Home-made linkage rods will
connect the levers to the shift rods on the transfer case.
The three transfer case shifters will all be pretty low to the ground
inside the Jeep, to avoid interference with the tranny shifter. Since
the NP203 shifter will be on the right of the transmission tunnel, and
the D20 twin-sticks will be on the left, all three should line up pretty
will in a row, 6-8" in front of the center console.
Radiator and hoses
The radiator was another one of those things I decided to ignore until
the swap was done, since I had no idea if the factory YJ 4.2L radiator
would provide enough cooling for the 5.0L. After hooking everything
up, warming the engine up, and working all the bubbles out of the cooling
system, it looks to be allright. My rad was re-cored a year or so
before the swap (some incentive there for me to keep it), and I'm running
the factory YJ fan shroud, the factory 5.0L thermostat, and the factory
5.0L mechanical fan and fan clutch. The engine runs a little warmer
than the 4.2L did, but not by much. And that temperature hardly budges
on hills, in the city, or on the freeway. We'll see how it does in
the heat next summer, I guess!
For lack of anything else to aim for when deciding on the engine placement,
I decided to put the 5.0L's fan more or less smack in the middle of the
YJ's fan shroud, with about half an inch of clearance between the fan and
rad fins. So no modification of the shroud or rad mounting was necessary.
As for the rad hoses, fortunately the Mustang and YJ radiator inlets
and outlets are on the same side, all I needed to do was come up with some
hoses to connect my old rad to the new engine. I was pleasantly surprised
to see that my original YJ lower hose connected up just fine. In
fact, both of the hose fittings on the 5.0L are the same size as the ones
on the 4.2L.
The upper hose wasn't quite so cooperative. I ended up splicing
together the motor-end of the factory YJ upper hose to a chunk of the factory
Mustang upper hose, using a PVC hose splice from the local Home Despot.
I was warned against using a galvanized steel splice - apparently antifreeze
and the galvanizing material don't play well together. Here are two
pictures showing the hybrid rad hose:
Power steering
Here's another part of this project that I lucked out with. I had
the pump-end of the Mustang high-pressure PS hose spliced to the gearbox-end
of my original YJ hose, hooked it up, hose-clamped the YJ return line to
the Mustang pump, and... it worked! A local hydraulic hose shop did
the splice for me. Both hoses are 3/8" ID, so this worked out well.
Now, I don't have a PS cooler and I haven't really stressed the PS system
yet, but so far on the street and during some mild 'wheeling, it hasn't
given me any trouble. I've read that a PS hose from a 91+ YJ with
the 4.0L has the same pump-end fitting as the Ford PS pump, so it would
be a "bolt-in" hose for this conversion. If my spliced hybrid-hose
fails, I'll replace it with one of those. My spliced hose is somewhat
visible in the photo in the next section, down below the oil filter.
Oil filter relocator
Not long after getting the engine positioned where I wanted it, I found
that the 302's oil filter port pointed right smack into the driver's-side
frame rail. This looked to be a Bad Thing. Fortunately (I suppose),
Lordco was happy to take more of my money in exchange for an oil filter
relocator kit. This kit includes an adapter that screws into the
filter port on the engine, and two hoses to connect that to a second special
adapter that the filter screws into. I mounted the filter up on the
driver's-side fender, as you can see here:
This location was chosen pretty much because it was the only place there
was room for the bloody thing. It's reasonably convenient, but it'll
probably be kinda messy when it comes time to change the filter.
Re-using the Jeep's factory
gauges
Surprisingly, it was possible to adapt every one of the YJ's factory gauges
to the new powertrain. While they're probably not the most precise
measurement device ever built, I was used to how my gauges behaved, and
they're a useful tool for getting a feel for how "happy" the new engine
is. Maybe someday I'll replace the whole package with an expensive
set of Autometer gauges, but that might require some significant modification
to the dash, if it's possible at all. For now, I'm happy to have
a complete set that match and are reasonably reliable. Here's how
each of the gauges was adapted:
-
Voltage: No changes required; the 302's alternator
puts out pretty much the same charging voltage as the 258's.
-
Fuel: The '93 sender I installed seems to
put out roughly the same signal as my '89 sender did, so for now I've left
this one alone as well. It reads a bit high though, so I may try
and calibrate it using the same method I did for the tach.
-
Clock: Duh.
-
Oil Pressure: I adapted a YJ oil pressure
sender to the 302 using a plain old brass 1/8 NPT to 1/4 NPT adapter, so
the gauge should be pretty consistent. The 302 runs at a higher oil
pressure than the 258 - no surprise there I guess. I did have to
cut off the connector on the 302's sender wire and splice on the YJ's in
its place - no big deal though.
-
Temperature: Again, I adapter the YJ's sender
to the 302. A different brass adapter was used (1/4 NPT to 3/8 NPT
I think - can't remember for sure). The YJ sender's tip doesn't stick
right down into the coolant like it should because it's spaced up by the
adapter, so it's necessary to bleed the air bubble out from under the sender
by loosening it when the engine's hot until coolant starts to ooze out
through the threads. Careful not to loosen it too much!
-
Speedometer: I found an aftermarket stock-replacement
Ford speedo cable at the local Lordco that fit the EB D20 transfer case
and speedo gear (I guess Ford used that style of pickup on a few types
of cases). It proved to be a good length for the Jeep, which was
nice. A little grinding of the hole in the firewall let the speedometer
end of the cable pass through, and some more grinding of the cable fitting
on the speedo itself was needed in order to get the cable to mate to it.
Even then, a couple of tie wraps were needed to hold the end of the cable
onto the speedo. No changes were made to the cable, since I may need
it intact someday if I put in an aftermarket speedo (or a Ford one?).
I cut the rubber grommet off the YJ cable and put it onto the Ford one,
to seal the hole in the firewall. Calibration will mean getting my
hands on the right speedo gear - as it is, the yellow one that came with
the D20 is making the speedo read a little high, so it should be possible
to get it right on with a couple of trips to the dealer (ick).
-
Tachometer: This was a tricky one, with a
cool solution. Factory tachometers are typically set up to work with
the stock engine: a 6-cyl YJ will have its tach set up for the 6-cyl engine,
the 4-cyl for the 4-cyl, etc. This is because the tach works by measuring
the frequency at which the ignition module fires the spark plugs, so my
6-cyl tach expected to see six firing pulses per motor revolution.
That meant that when I hooked up the V8's tach wire to my old tach, it
read high, since the 302's ignition puts out eight pulses per revolution.
I spent some time taking my old tach apart, trying to figure out how it
worked, before coming across this
clever article at Off-road.com. It's an elegantly simple solution
to the problem of recalibrating a tach after swapping in an engine with
more cylinders than the old one. I used a 1k-ohm variable resistor
set to around 500 ohms (calibrated using a frequency meter) soldered across
the meter leads inside the tach, and now it reads perfectly. The
resistor bleeds off some of the current being fed to the meter, lowering
the reading by a fixed percentage throughout the useful RPM range.
Easy and cheap.
The vacuum system
There were vacuum schematics included in the electrical drawings I bought,
and in the Haynes manual. I got the Mustang's vacuum harness with
the engine I bought, and it looked pretty straightforward. There
is a solenoid harness with several hard plastic vacuum lines for the two
air pump solenoids, the EGR valve solenoid, and the vacuum reservoir.
This harness attaches to an engine harness with more hard lines going to
the air valves, the EGR valve, and to the intake manifold. The rest
of the vacuum lines are rubber, and are centered around a plastic five-port
vacuum distribution manifold, which has is ports marked for easy hookup.
One line is source vacuum from the intake manifold, one goes to the brake
booster, one I connected to the YJ's fresh air vent motor, and the other
two I capped. Here's a picture of it:
The 302 seems to put out enough vacuum for the YJ's brake booster.
The brakes still work, at least...
The solenoid harness got mounted to the passenger side of the firewall,
below the starter solenoid near the battery tray. Since the solenoids
have to connect to the wiring harness as well, they had to be mounted in
this area to get everything to reach. Even then, I had to splice
in 8" extensions to the wires going to the solenoids.
Rather than figure out mounting for the Mustang vacuum reservoir, I
just re-used the YJ's, and capped its second, unused port. Its location
on the passenger-side fender was ideal.
A custom exhaust
There were a whole bunch of options here. To keep costs down, I decided
to run factory truck 302 exhaust manifolds. Conventional wisdom is
that manifolds are better for low-end torque, and I'd been told that the
factory Mustang headers would interfere with the YJ frame rails.
I didn't actually confirm this, but I'd bet its likely given the amount
of space available and the length of the headers. Another factor
here is the clutch external slave cylinder. The F150 and other trucks
with this setup (and the 302) have the exhaust pipe connection on the driver's-side
manifold set further forward than on the passenger side, so the Y-pipe
avoids the slave cylinder. It's important to note that Marquis and
other car manifolds will not work with the external slave setup, since
their left-side manifolds don't have this feature.
The downside to using truck manifolds is that the truck 302 only had
one oxygen sensor, so I had to have my custom-made Y-pipe made with a sensor
bung welded into the left-side downpipe. K&N sells these weld-in
bungs for a few bucks.
Anyway, as you may have figured out, I ran a single exhaust. It
runs down the passenger side of the Jeep, opposite from the front driveshaft.
Local smog laws require that I run a catalytic converter with the same
air-pump feed that the Mustang had (thankfully I don't have to run dual
cats like the 'Stang). The cat I chose is a 2.5" 3-stage Walker,
center-in/center-out, and it's followed by a Flowmaster 3-chamber 2.5"
center-in/center-out muffler. The Flowmaster is built very tough
- it should last a while, and it sounds good too.
As much fun as a dual exhaust might have been, it would've cost me twice
as much in mufflers and cats, and I very much doubt there would've been
room to run a cat and muffler on the driver's side, with the front driveshaft
taking up room over there as well. If you don't have to run cats,
it is possible to run dual exhausts - I've seen it done once.
The shop that installed the exhaust for me re-used the YJ's exhaust
hangers, and I left the muffler heat shield in place under the tub.
When I got the Jeep home after the exhaust was in, I hooked up the 302's
catalytic converter air feed outlet to the cat using heater hose (from
the check valve on the engine) spliced to a section of teflon hose that
connected to the cat's air tube. This special high-temp teflon hose
is part of a kit for doing exactly this kind of thing. It's made
by Walker, p/n WAK-35574.
On to the next section: Doing the swap!
Back to the Powertrain Swap page
