Gunn's 3.8L to 5.0/302 Swap DIY (Notes)
Unlike my previous 3.8L single port to splitport 5.0 swap, this DIY will have far fewer pictures because a) I didn't take as many of them and b) they simply aren't necessary because you aren't fabricating any new parts (like that a new fuel rail and the whole throttle body mess with the Windstar). Instead, this swap was more straightforward mechanically but much less straightforward electrically (since I started with an 95 chassis vs. an 89-93). I've been told that this swap is much more plug and play with an 89-93 chassis but you go with what you have.
CURRENT STATUS 3/11/2014:
Engine runs and idles just fine now. For a while, I had an issue where the engine would run just fine at speed (was able to drive it on a 200mi round trip) but had a hard time idling (when warm, it would try and die if allowed to drop below 1K RPM). I tried a bunch of stuff (see below for diagnostics) but ultimately, it looks like I was having a problem with my IACV and a bad coolant temp sensor (it fell apart when I tapped it). I replaced both and the engine runs just fine -- hot or cold -- now. My last remaining issue is tracking down a small coolant leak -- it's either at my thermostat housing (most likely) or at the lower intake (less likely but also a distinct possibility).
All in all, this conversion took me 225 hours (vs ~150 for BOTH splitport iterations -- Mustang and Windstar). I would attribute a good deal of this time to my desire to rebuild the bottom end of the 5.0 though (coupled with my inexperience in this kind of conversion).
RECOMMENDATION 1: IF YOU WANT a 5.0 TBIRD AND HAVE A V6, JUST BUY A 5.0 TBIRD AND SWAP YOUR PARTS OVER.
This will be a LOT easier. The only reason I didn't take my own advice here is because I have $1500 into a professionally built roll cage in my 95 chassis.
- You will be buying a 5.0 tbird anyway to cost-effectively get the tbird-specific 5.0 parts (see below)
- Many of the 5.0 tbird parts are an upgrade for a V6 car (rear axles, TL unit) so if you will be swapping them from the V8 to the V6 car anyway, why not just leave them on the car?
: Whether or not you keep your existing tbird or just trade it for the 91-93 chassis, consider rebuilding your your 5.0!
- The newest 5.0 tbird block is 22 years old now and I'm willing to be that 99% of them have at least 100K mi on them. While my sample set is fairly small (2 engines), from what I can see, the 5.0 engine is pretty worn after 2 decades and 100K mi.
- Even if you are keeping the 5.0 chassis (and therefore skipping all my electrical notes), take the effort to pull the engine and refresh it. At the very least, pull the pan and check the bearing clearances with plastigauge to confirm how worn out it is. You can then either buy a slightly newer explorer motor and swap the tbird specific parts over or rebuild your existing block.
- I was shocked about the affordability of the 5.0 bits: better cam? $185. New (uprated) valve springs? $150. Reground/reman crank w/ bearings? $150. Timing chain set? $30. This even extends to transmission parts: New Flywheel? $50. Clutch Kit? $70. Starter? $30. Seriously -- this stuff is stupid cheap so if you are taking this car apart, you might as well put it back together properly.
Anyway, if you insist on swapping over a 5.0 into your car, here's a documentation of what I learned. I couldn't have done this without Dan's help (SCTbird1994) -- esp the bottom end rebuilding -- or without the advice of MadmikeyL and Rayo.
Baseline (what I Started with)
V8 Decision - 4.6L or 5.0
- 1995 Ford Thunderbird 3.8L N/A Chassis
- M5R2 manual transmission w/ 89 SC flywheel (28oz imbalance) and 89SC clutch
- Stock Hydraulic clutch line
: I went 5.0 simply because I had two M5R2 manual transmissions already. The other options are:
- Go with a 4.6L and make a shifter relocation bracket for the matching T45 (or whatever it is) transmission.
- Go with a 4.6L from a 91-92 4.6L out of a Panther car (Town Car/Crown Vic/Mercury Grand Marquis). As I undestand it, they are called "b-stard" blocks because they have the AOD bellhousing pattern (to match an AOD or an M5R2) vs the more common "modular" bellhousing pattern. The catch is that they are fairly rare 23 years later. You are also opening yourself up to a whole different kettle of electrical wiring madness (adapting the towncar ECU and other bits to the tbird chassis).
Q: For an M5R2, which flywheel/starter to use?
Q: What flywheels will be compatible with a 5.0 engine + M5R2 transmission?
Having committed to a 5.0/302 swap, this was the first decision I had to make. I already had 28oz imbalanced flywheel bits from an early SC to use with my V6. However, the 5.0HO as found in my 93 tbird donor cars (1 for racing, 1 for spare) have a 50oz imbalance. This means that in addition to acquiring a second flywheel, I would have to pay a machinist to rebalance BOTH flywheels to 50oz... a somewhat costly option which worried me a bit as this procedure has mixed reviews. Personally, I was skeptical myself of such a procedure.
- As an alternative, it was suggested to me that I might do better in endurance racing with an early style 28oz imbalance crank (1968-80). This would allow me to re-use my existing SC flywheel but since I had two engines, this would leave me with having to find another 28oz imbalance flywheel (early model SC) and pay for resurfacing of THAT disc as well.
- My solution? Raid the F150 parts bin. MadMikey told me that several years of F150s came with both my chosen engine (5.0 w/ a 50oz) and my chosen transmission (M5R2) so it was a simple matter of picking up a new flywheel, clutch, and starter for a "1995 Ford F150 5.0 V8 RWD".
There were only two downsides of going with an F150: different starters and slightly smaller (1/2") clutch discs. However, just taking a look at the F150 clutches and flywheels I purchased, they looked plenty beefy to me. While the starters are different from the truck to the cars, these parts were all cheap. Since SC flywheels are decently valuable, I was able to sell off my old flywheel without any fuss to recoup a good amount of my new transmission needs.
Parts Acquired from Donor Tbird
You will need the following items from your tbird 5.0 as they are tbird specific:
(can also be bought here but IMO it's not cost effective -- you want the Type 6 ones: http://www.turbochuck.com/motormounts/
). Given their age, you may have to replace the rubber bits OR make your own (see below).
High Pressure Power Steering line
The high pressure PS line from the pump to the rack is different. Either (95+ or 93) low pressure line (from the rack back to the pump reservoir) will work but I kept my chassis's low pressure line since it included a provision for an external PS cooler (or in my case, I actually plumbed in a second one for a total of TWO PS coolers. Silly yes, but hey, it's endurance racing).
UPDATE (7/4/2014): After my last track day, I got sick and tired of having the PS low pressure line leak because the line as it mounts to the reservoir had cracked so much that there was a constant dribble. Since my car is stored for months at a time between races, having it puke out all its spendy Redline PS fluid was getting annoying. The solution was to buy a new PS reservoir with a nipple that exited towards the bottom, notch my accessory bracket as needed, and run a new PS line to the PS cooler. See this thread for part # and more details.
Only the tbird specific one will fit without modification. I added a deeper oil pan but considering the extra work required, it might be more trouble than it's worth (certainly for a street vehicle).
Specifically, the section from the fuel filter forward to the engine. You need longer ones to replace the stock v6 ones. WARNING: Do NOT get cut happy here. I lost my backup set to my snip happy buddy and that's probably the only part I don't have a spare of now. I also got snip happy myself and had to rebuild the return line connector. The key is to disconnect all three fuel related lines (incoming, return, and vapor line) under the car behind the fuel filter at the removable connection. Luckily, I snipped the return line so the pressure is low enough that I don't mind replacing it with hose (my ~$20 Dorman fuel line repair piece had a connector mis-match with my chassis and therefore leaked a bit under pressure. Total waste of money).
If your chassis was a V6 N/A, you will need to replace the original 60lph fuel pump with the 88lph one from the 5.0 car. Or, you can just upgrade it.
93 5.0 thunderbird
5.0 Bell Housing Bolts
I noticed that I needed to use the bellhousing bolts from the 5.0 vs. the ones I used with my 3.8L N/A. I suspect it's because the bolts on the 5.0 were SAE (7/16-14 x 2" to be exact) while the ones I used on my 3.8L N/A were metric. Take them off the donor car or if those look like crap, just buy new grade 8 hardware at your local HW store.
The main computer for the 5.0. It was supposed to work with an AOD so it doesn't mess with the transmission at all (perfect for my M5R2)
Passenger side engine bay harness
This is the harness that goes through the firewall and terminates at the ECU plug. Since the 95 car had a provision for the CCRM (the module that contains the fuel relay and the main relay), I went with the 93 harness.
Rear 5.0 Axles
They are thicker than the ones that came with my 95 tbird V6. I pulled them with the spindles attached so replacement was a simple affair.
Most 5.0s came with a traction lok unit which may be preferred if you have an open diff.
TIP: Rebuild it.
93 ignition control module
Its mounted between the airbox and the passenger side headlamp. You are looking for a small box with heat sink fins on it.
O2 Sensor extension harness
There is an 1-2' long extension cable that connects the passenger side O2 sensor to the passenger side engine bay harness. Don't forget to grab it or you will need to cut into your engine bay harness to make this sensor work.
93 tbird MAF, intake tube, and airbox.
While a 95 3.8L N/A MAF is larger, you will need a tune to make it work properly. If you (like me) are going to be stock for the initial setup, stick with the stock 93 MAF.
Either the 91-93 radiator or the 95 radiator will mechanically fit the car so I just pressure tested all of mine and picked the best one (again, I'm trying to be frugal here for Lemons -- not all aluminum fancy pants stuff for me. A 91-93 radiator can be adapted to fit both the mount points (which are slightly different up top) and the radiator fan with some easily fabricated brackets.
Optional: electrical wiring
I harvested and sorted a good deal of the electrical wiring from my donor car -- especially the long runs that went from the dash area towards the rear of the car. This proved invaluable when I needed to make additional circuits.
Optional: battery cable
It's not very long but if your battery cables are in decent shape in the donor car, cut them out and use them for the additional grounds I cited below.
Technically, the 5.0 exhaust positioning (where the exhaust manifolds sit) should be compatible with the 3.8L exhaust so you should take a look at both systems and pick which one looks best.
Recommended: Fuel Pump Access Panel
Cut a panel from the metal floor from 93 tbird just above the fuel pump to make an access flap (see below).
Recommended: grab the Fuel Relay and its base from the trunk
You can use it for an electrical fan OR you can use it for your fuel pump (see below)
The suspension on a 5.0 tbird IS stiffer than the ones found on a 3.8L N/A so if you haven't upgraded your 3.8L's suspension yet, you might want to look and see what your donor car came with.
Engine Internals / Upgrades To Consider / Prep Work
While it's less likely that you will need to get them ground flat like aluminum heads, your valve seats are probably pretty worn after 100K mi. A leaky valve seat was the likely cause of low compression in one cylinder on my "race" engine.
OPTIONAL: Head Upgrades
There are two options for more power on a budget
- port the e7 heads. Note: Porting Iron is a LOT more time consuming than aluminum. http://www.diyporting.com/E7OV.html
- go with GT40 "3 bar" heads. Seeing what they go for on CL (~$300+) and considering how much they weigh, the only cost effective way to acquire them is to pull them yourself from a 96-early 97 Ford Explorer. You can still find them in junkyards (even after cash for clunkers killed off a bunch of them) and they seem to keep their value in case you decide to go with spendy aluminum heads in the future.
- go with GT40P heads from a 97+ Explorer: the change in how the spark plugs go into the heads will force you to add spacers (i.e.: cut off the flanges from some other exhaust manifolds) AND redo your exhaust from the manifolds on as they will be positioned farther away form the engine. Unless you are getting the GT40P heads as part of a fresher, lower mileage Explorer engine you are planning to drop in after swapping the oil pan, I'd skip it.
- Any engine you are rebuilding will have old springs. If you are already taking apart the heads to redo the valve seats, you might as well add newer springs.
- You can re-use the stock ones but if you do, you should recondition them. At the very least, buy the rebuild kits for a dollar or two each to replace the pintle caps and seats.
- Or, for a few bucks more, you can have them flow/spray pattern tested, reconditioned, and re-tested. I found Mr. Injector to be fast, affordable, and offered timely service.
- OPTION: upgraded injectors. You can also upgrade the injectors at this time because the stock injectors are close to their operational limit. However, you will need to tune the ECU if you go this route.
- All 91-93 5.0s use roller cams so this part is less likely to be worn even after 100K+ mi. Mine showed a little wear but nothing that can't be tolerated.
- Since the engine is apart though, you might want to consider a hotter cam. An e303 cam won't require a tune BUT will require newer springs to avoid valve float.
- Conversely, if you are adding new springs and the block is apart, you might as well add a new cam. Don't forget new cam bearings.
Timing Gear & Chain Set
They are cheap so if you are taking apart your engine, buy a new set.
This would seem obvious to replace given their cost.
RECOMMENDATION: Simplify the Engine
Remove the excess components. For my application (road racing), I didn't need a bunch of stuff so there wasn't a compelling need to figure out how to make it work.
- I don't have a heater core and furthermore, with the extra deep oil pan (see below), the 180 degree loop I was using to bypass the heater core was hitting the firewall upon installation. My solution was to cut the crossover pipe and then install it with a small stub pointing forwards (instead of backwards). This way, the fixture attached to lower intake manifold has only one provision for a temp sensor and then goes straight to the hose from the water pump.
- EGR: removed and a simulator plugged into the harness
- Smog Pump: removed. You will also need to weld a cap for the exhaust manifold.
- A/C compressor: ha! removed.
- Mechanical fan: this thing terrified me. I had no interest in getting my fingers near it. I also had to cut it off to get the WP off because it was so corroded on. Luckily, my 95 tbird has an electrical fan so all I needed to do was wire a switch and power relay for it.
- Simplify the vacuum connectors. You really only need 2 vacuum lines: one small one for the fuel pressure regulator and a larger one for the brake booster. I also hooked up the PCV valve from the lower intake manifold to the upper intake because that was easier than capping it and I ran another line from the upper intake to the nipple on the valve cover. All the other lines were capped.
Track Car: Simplifying the vacuum lines on my 5.0/302 engine...
NOTE: removal of both the smog pump and A/C compressor required a new routing of the belt. The instructions I found online for 5.0s was correct but the length needed was wrong. You need one that is 84.5" long
OPTIONAL: Manifolds/Header Upgrades
- Stock ones look tiny but anything better will either cost $$ or require the steering shaft to be relocated
Thunderbird/Cougar Steering Shaft Mod
OPTIONAL: Deeper Oil Pan
Oh man, I really made my life harder with this one. You can't really go wider b/c of the exhaust on the driver's side and the starter on the passenger so my solution was to go deeper -- 7qts to be exact over the stock 5qts. While you can fab this up yourself (provided you clean your old oilpan well so it doesn't catch on fire, you will also need a deeper oil pump pickup (relatively cheap from Summit Racing) This necessitated in notching the sub-frame and then for added peace of mind, I welded additional supports around it. This wasn't too bad b/c I already had a subframe out of the car I could notch and then test fit. Once I had the width down, I went and did it on the one still on the car. While this would have OK, the real problem here lay when I finally tried to fit the stupid engine into the car with the transmission. Even if I had unbolted the M5R2, there simply wasn't enough room to manuever the engine into position WITHOUT DROPPING THE SUBFRAME. The engine kept hitting the TOP of the transmission tunnel before the bottom end of the extra deep pan would clear the rear hump. Please note that this was after I raised the engine approx 0.5" (3 hockey pucks instead of two -- see below) over stock. To finally fit the engine, I raised the car, unbolted the rear 3 bolts on each side of the subframe, unbolted the struts from the car, and then loosened the front subframe bolts so the subframe would sag down and give me enough clearance. It was a total PITA.
Bottom Line: for a road car, I wouldn't bother with a bigger oil pan. For an endurance racing car, I probably would skip this upgrade had I known the trouble it would cause as well and figure out a way to hide an accusump (another reservoir which can supply addt'l oil on demand) in my budget (esp if I wanted to have the option of speedily swapping engines.)
Summary of Other Parts I Acquired based on my Decision Points Outlined Above
- 1995 F150 5.0 starter
- 1995 F150 5.0 clutch
- 1995 F150 5.0 flywheel
- New valve springs
- New camshaft & bearings (if desired)
- Reman/reground crank (if your existing crank is worn, a reman crank may be cheaper than getting your own reground. I bought a few from Autozone with free sihpping and just picked the best one -- aka the one with the smallest oversize bearings)
- O-ring for the PS pump (larger ring from kit, Dorman #82540)
- 1995 Ford shop manual & EVTM -- I couldn't have finished this project without these manuals
- 1993 Ford shop manual & EVTM -- you can buy both books for $10-15 on eBay
- Hockey Pucks & Grade-8 hardware (see below) for Engine Mounts: 1/2"-13 bolts, nuts, and lock washers. 3.5" long for 2 pucks, 4.5" long for 3 pucks
- Clutch line from hydraulic shop
- Shorter accessory belt: 84.5" (#845K6)
- Gasket kit
- Optional: thermostat housing (these are aluminum and mine actually broke when I unbolted it)
- Optional: New rear disc rotors & pads
- Optional: additional 00, 0, or 2 gauge battery cable for beefy grounds/power cables. You can buy battery cable lugs that crimp on from your local auto parts shop