A little help before I start my 4-to-8

My simple GT40 headed 87 LX ran 12.80s over 20yrs ago.

There is also the issue of upgrading the entire car to deal with the Coyote power, or even a healthy 347. Some things that first pop up in my mind are 4 cylinder brakes are going to be scary. You’ll need chassis reinforcements (subframe connectors and you might as well reinforce the torque boxes). The transmission will not live long behind the 347 (will a T-5 fit on a modular? I doubt it). Is the rear end diff a 7.5” on the 4 cyl that year? A built 8.8” should do fine. The rear control arms and bushings need upgraded.

Sirwa said:

I would like to thank you guys for all the suggestions, does anyone have a rough estimate on the cost of a beefy 347 vs a coyote? I want it to be a fun daily driver so I'd like all the fixings.

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When you swap a 4-8,it's a HUGE undertaking. It used to be pretty easy when Foxes were plentiful and cheap. You could find a wrecked 5.0 car and just swap everything over. You're going to have to decide which direction you want to go. IMO,the easiest swap would be a 302ci based bottom end with GT40 stuff and a carb or something like the Holley Sniper efi. Then you will need to decide if you want a manual or auto trans, and don't forget the 8.8 rear as well. Budget 10k as a starting point.

Mechanical

To convert the car over to a 302W based motor you can use the 4 cylinder K-Member with V8 mounts. Parts stores still carry the V8 motor mounts and they are usually the Anchor brand which are okay. I would bite the bullet and get the Energy Suspension units but that is me. You will need to rebuild the lower control arms with new bushings and new ball joints so run quality stuff there. I used to run Moog and hopefully they still have good stuff. You should swap out the front springs and struts at which point I would suggest you at a minimum install the 87-93 V8 spindles and brakes. If you want to upgrade to five lug brakes later down the road the Fox ball joints will work with 0.330" of spacer or washers. Search this and lots of info will come up. You should also strongly consider installing the Maximum Motorsports caster/camber plates so you can dial the front alignment in.


Other items you may want to change out would be power steering rack (if it is in good shape leave it), inner tie-rods, outer tie-rods, and the rag joint between the steering column and the rack and pinion. If you change the rag joint do not let the steering column shaft rotate as this could damage the clock spring (do a search on this).

Engine Control

If you want to run the stock fuel injection then you will need year specific engine harness. Go here for engine harness discussion (feel free to search as well):


My guess is you will want to run mass air rather than speed density. If so then the '89 harness is the only one that will work for mass air from the factory unless you can get your hands on an '87 or '88 harness from a California car as they were all mass air. If you get an '87 or '88 harness then you can get the mass air conversion kit like the one from Pro-M Racing:


If memory serves me right you will also need to make sure the VSS signal from the transmission makes it back to the EEC. Here is the writeup on all of this:


The O2 sensor harnesses are also different so pay attention to that as well.


Next on the wiring is the injector harness that will connect to the salt and pepper shakers (all hail these and the mighty mighty B cam - could not help myself). This is the harness that connects everything on the lower intake to the main engine harness and they are the same from 87-93.

Last item is the alternator harness. The 4 cylinder wiring is too short being the stock alternator position is on the driver side and the V8 is on the passenger side. You have three choices here.

1) Convert to a 3G alternator as this requires a new charging cable from the alternator to the battery (4 ga) and extending the remaining wires.
2) Keep the stock 75A alternator and extend all of the wiring.
3) Keep the stock 75A alternator and replace the headlight wiring harness with a V8 one (alternator wiring is in this harness).

I would just swap to the 3G alternator and be done with it. Quick search on here and you can see how to do it. Please fuse the power wire accordingly.

I think that has it as far are electrical and mechanical to just get the motor in the car. There will be other odds and ends but this gets it in there.

Transmission

You will need to start gathering up the 5 speed, bell housing with pivot ball, spacer plate, flywheel, clutch, throw out bearing, clutch fork, clutch cable, and transmission mount. The transmission crossmember can be reused but you will have to grind the spot welds on the tubes so it can slide back on them. I would strongly suggest you get a positive stop shifter as they are proven to help the life of a T5. Optional stuff would be a firewall adjuster and an aluminum quadrant. All this is assuming you are going manual being the car is already a manual.

I believe you can reuse the stock drive shaft but others will have to step in here as I went with an aluminum unit so no experience here.

Rear End and Rear Suspension

The 7.5 will survive for a while but eventually you will want an 8.8. I would suggest that you also get new rear springs and shocks that match the front as this is important for handling. Maximum Motorsports has spring isolators and you should get them as it will keep the squeaks down. If you are going to stay with the stock geometry suspension then get new upper control arms (UCA's), new bushings to go into the rear end UCA attachment points, and some good aftermarket lower control arms (LCA's). This will allow you to ditch the quad shocks which were Ford's band aide for wheel hop.

Exhaust

You will need exhaust manifolds or headers. Choices are all over the place but I prefer shorties for starter serviceability and ease of install compared to long tubes. You will need the mid pipe section (H or X with or without cats) and then the cat back section which on your car will be the LX tips and please get stainless they just look better on those cars.

Depending on which way you go as far as the engine control (stock or aftermarket) you need to look at O2 sensors or wideband.


Fuel System

Swap the stock fuel pump out as its either old or unknown and install a 255 lph pump like a Walbro or Aeromotive and change the fuel filter. The hard fuel lines on a 4 cylinder will not work for a V8 so that needs to be addressed. You can either run AN lines (get lines good for ethanol) or find some off a V8 car and swap them.

Chassis Stiffening

Install full length subframe connectors that weld in. Again I will suggest Maximum Motorsports units as they are built well and have good installation instructions.


Another option is Global West but what they recommend will end up more expensive but I think they are a little stiffer and do not hang down below the car as far. You will need the full length subframes, the rocker rail kit, and the seat supports.


I run the Global West units in both my cars and really like them but either one will work.

That's all I have. I am sure I missed some things but as you can see this is not something that you just piece meal together. When I swapped my Coupe 20 years ago I had al the suspension parts in the shop, all the fuel system, all the wiring, fully dressed motor, transmission and associated parts. Took me 7 days to do the swap. I will say I had already changed the front brakes over to the V8 units and just used shims on the 4 cylinder struts until I did the engine swap.

I swapped in a 302 thirty over at about 10.5:1 with good heads, cam, cobra upper and lower, Pro-M MAF with 24 lb/hr injectors and the car ran great like that for years. Made about 250ish to the rear wheels and was a blast to drive.

You should check out this build while still bench racing. Scroll up to posts 181 and 182.