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I bought this chassis over 3 years ago now, but my previous employer had me gone way too often to ever make any progress on it. It came with a "rebuilt" (we'll get to that later) EFI 5.0 out of a ~97 Mercury Mountaineer (Ford Exploder) and T-5 manual transmission on the side. While I've been away, I've been collecting all the parts I think I needed to get her on the road for the first time in over a decade. With a new job, I'm actually home now and can start to play with this a bit.
My goal is to document all the fitment issues with resolutions in this thread and have at least a few updates a week to keep me motivated. It came with a Granny's 5.0 swap kit that is supposedly bolt-in, but it hasn't been anything remotely close to that easy. I'm not a Ford guy, and learning how to mix and match all these pony parts has been a challenge. The previous owner did it... wrong. That's part of why I'll be using a Speeduino (similar to a Megasquirt, but cheaper)--the Ford ECUs don't cope well with changing major engine components.
First order of business: don't start with an Exploder motor. We'll get to why tomorrow Just buy a Fox Body Mustang motor and be done with it. Until then, here's the car when I brought her home at the end of 2017 and the drivetrain before I dropped it in (and swapped out the heads...).
A carburetor or an aftermarket throttle body doesn't care where the engine came from. The explorer/mountaineer engine has better cylinder heads than the ones used in a Fox mustang so that is why it was used. The engine in the picture has GT40P heads for example. Explorer engines also used a direct fire ignition that was not used in the earlier fox mustangs but might have been in 94-95 Mustangs.
This is a common discussion item on Fox Mustang FB pages or on Mustang forums like the Mustang Corral. There are also engine swap sub forums on this site that would be a better place to look that this sub forum
A carburetor or an aftermarket throttle body doesn't care where the engine came from. The explorer/mountaineer engine has better cylinder heads than the ones used in a Fox mustang so that is why it was used. The engine in the picture has GT40P heads for example.
...and this is exactly why I wanted to create this thread. You're absolutely right about all those things, but my point is to show why GT40P hardware is bad for an FB swap: the P in GT40P stands for Problems. I'm not using a carb, and the cam (rather than the TB) is the problem with the stock computer.
For non-Ford folk: The 5.0L Explorers of this era came with GT40P "four bar" iron heads (similar but better flowing than Fox Body Mustang; we'll just use P for short), direct fire injection (good for aftermarket EFI... more on that another day), a better-flowing intake, a larger throttle body (65mm vs 58mm), and a truck camshaft (which needed to go).
Intake: this was my first problem. A couple corner mounting bolt bosses for the P upper intake are all the way at the top and interfere with the hood latch. Fox upper intakes have all the bolts at the flange and drop down below the latch.
Headers: The spark plug angle is different on P-heads from everything else which limits header choices. Yes, you can protect your wires from the heat and use normal ones, but it's still really tight. In addition, the tubes have to go to the collector in a way that doesn't interfere with the steering box. I finally found a set of MAC non-P headers that would clear that, but I'll have to turn the collector flange or beat in the corner of the unibody on both sides. It's close though.
Oil Pan: You need the Mustang pan. Thankfully the PO already sourced and installed that piece.
Valve springs: P-heads have light springs and will result in float at higher RPMs with an aftermarket cam. I forget why, but the P rocker pedestals are different, are a pain to work with, and have limited options.
Cam: The engine came with a box for a Comp flat-tappet camshaft (and an old Mustang cam inside?), but I didn't trust that's what was installed since a flat tappet cam would destroy a roller block. I'm glad I pulled it out because it was that WRONG flat tappet cam after all.
Accessories: This is the main advantage of the Exploder motor--the belt drive doesn't stick out as far which leaves more room for a radiator & fans.
Water pump pulley: This was another hard part to find. The Exploder one is different than the Mustang and discontinued. I had to call junkyards on Car-Part.com until I found one with a water pump listed who would sell me just the pulley. I couldn't even find one on eBay.
So with intake, header, and valve spring issues, it made more sense to go with the cheapest aluminum head with springs I could find, Flo-Tek, and a used Fox intake. I sold the P-parts for $500 which put a lot toward the new parts. Flo-Tek are also way lighter than the P. The Ford E303 is ancient, and Comp has too many options to sort through, so I went with a TFS Stage 1 cam. If my car didn't come with that 5.0L, I would have just bought a Mustang motor and dropped it in.
Last edited by delturcious; 01-11-21 at 08:58 PM.
Reason: 3->4 bar.
Since you were able to flip the GT40P stuff and pay for part of better parts why are you complaining? Also 3 bar heads are not GT40P heads they are just GT40 heads. GT40P heads have 4 bars and a wonky spark plug location. Explorers came with the 3 bar head first and then the 4 bar head. SCCA A Sedan guys made over 400HP with those heads back when they weren't allowed to run a spec aluminum heads
You can run a flat tappet cam in a roller block. I ran both a hydraulic and a mechanical flat tappet in my 85 roller block. The mechanical cam was cheap and pulled hard to 7500. Back when I was putting that stuff together there weren't allot of hyd roller cams that could RPM like that and not pump up or loose oil pressure. My engine was in a dedicated autox car.
Also 3 bar heads are not GT40P heads they are just GT40 heads. GT40P heads have 4 bars and a wonky spark plug location. Explorers came with the 3 bar head first and then the 4 bar head.
Fixed to 4 bar above; thanks. Again, the whole point of this is to save someone else some fitment headaches with Ford parts that are usually easy to swap around on other Fords.
Originally Posted by mustanghammer
You can run a flat tappet cam in a roller block. I ran both a hydraulic and a mechanical flat tappet in my 85 roller block.
You can if you have the matching lifters. My engine (incorrectly) came with a flat tappet cam but hydraulic roller lifters/dogbones/holddown. I could've just swapped to the other lifters, but then I'd have to deal with camshaft break-in, and that was one more thing I didn't want to have to learn about on this build.
01-10-21, 05:58 PM
Just buy a Fox Body Mustang motor and be done with it. Until then, here's the car when I brought her home at the end of 2017 and the drivetrain before I dropped it in (and swapped out the heads...).
