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Fox 4.6 4v and 4r70 Swap

Discussion in '1979-1993 4.6L Conversion' started by RobotWrench, Sep 4, 2017.

  1. RobotWrench

    RobotWrench Member

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    Hello all, newbie here. Just bought two rollers last weekend for $1400, one 87 notch (sold awaiting pickup) and one 89 notch. The 89 was completely stripped to tie the frame together, got it completely stripped and gutted which is perfect for me as i wanted to tear down that far and dynomat and put racing seats up front with a cage and rear seat delete . Car came 5 lug swapped but still drum rears and unfortunately ranger spindles, with an unknown tubular k member. Previous owner sand blasted and painted the engine bay so its as bare as it gets as well. The car had the wiring harness still in the car and enough parts underneath to roll but thats is.

    Im hoping some members can set me straight on a few things as well as weight in a few opinions on parts.
    Ultimate goal is to 4.6 4v and 4r70 swap the car with coil-overs and full disk brakes.
    I attempting to build a jack of all trades car, one that can run down the strip, carve corners at a track and drive to work once or twice a month. I don't expect it to be the best setup of car for each event, but i do expect do at the least compete with some adjustments for each goal.

    I have already picked up a 99 teksid aluminum block that spun a rod bearing but has the forged crank so ill have it turned and buy bearings accordingly. In that same purchase i also picked up 2 sets of cobra C heads one set nearly complete but missing 2 valves as they needed them for a different build, and the other set is complete bare heads. Also a hydroboost all this for about $400 and at one stop, a win in my book.

    I've been setting on a 4r70w (3 bolt starter) that needs rebuilt for about 2 years that was going to be put in a 78 F100 but went a different route and finished what i wanted to do with it and sold that project.

    Im going to be buying the parts for the 4r70 and rebuilding it and sending the block and heads of to the machine shop to be checked out an worked accordingly while i sort out the interior of the car (cheapest part of the build probably). Once i get the parts back from the machine shop ill bang my head against the wall figuring out what compression pistons to order as well as connecting rods. Ill be going all forged components as it will eventually be a turbo car which is why i going auto as well.

    Now that the back ground info is out of the way hopefully i still have a few readers..

    #1 Steering and Suspension - I want to find different spindles to replace the ranger spindles that i just yanked out of the car. Since ill be going hydroboost with p/brakes and p/steering the early sn95 spindles seem to be the ones to go with for narrowest track? If this is the best choice could I use 03-04 termi brakes with the Sn95 spindle? I have a great lead on a fully loaded set front and rear for cheap. Also, would it be best to get sn95 pedals as well? It was a manual car so the pedals will have to come out either way.

    #2 Electrical - Plan to use the factory fox dash with cobra cluster from a new edge. It's my understanding that it will be best to use a for example a 99 cobra engine harness and ECU with the cobra cluster and retain the fox harness for p/windows and p/locks. Would this be a good assessment? If so i have some concerns on making the factory ignition work with the cobra ecu.

    #3 Heat and AC - Im assuming that i can use part cobra and part fox harnesses. If this is true i don't think ill have much difficulty getting everything to work as it normally would, but is there any headaches or set backs that ill run into with making a cobra compressor work with the fox hvac box aside from some fitting differences?

    If anyone cares to chime in on things they have learned or maybe tag links were some of this has been covered it would be greatly appreciated. I'm still new to the forums so I'm sure some of this has been covered but probably not all in one post.

    Electrical diagrams for this swap is greatly appreciated as well.

    Once i get to were i can post pictures and see all of the posts this may change to a build post with all inclusive info. I would love to make a start to finish sort of how to guide.
  2. cpearson1342

    cpearson1342 Well-Known Member

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    You can either go with the fox a-arms and will have the same track width as stock, or change to the sn95 arms to have it stick out further for better handling. You will simply use a sn95 ball joint for whichever you choose and will have no problems with the brakes from a cobra. You don't need the whole pedal assembly even though many on here use it. I simply use the sn95 brake pedal, cut the top of the brake pedal bolt shaft to move it over to the driver's side so it is the proper size for the fox assembly, and far enough over so the hydroboost plunger can slide over. This is a very important step so make sure you measure carefully.

    There are no issues with using the fox body harness and sn95 engine harness, other than the extra wires that will be on the engine harness, but you will need to be pretty good with wiring to complete this. Mine is setup this way, so if you need any help let me know. You really only need to feed some grounds, constant powers, and ignition power to the ecu itself, and just put the engine bay fusebox in place and should have no issue.

    You should have no problem with heat other than finding a new heater hose that is molded in a 90 and is otherwise the right size to go from block to heater core. I did my a/c by using the stock foxbody evaporator core, which I have to take out of the heater box, and had someone tig weld the ends from the sn95 core onto it at the right angle. Flushed it out with a/c flush and charged it with r134 and it works great.

    If you are interested in motor mounts to offset the engine forward (which will need to be done in most cases), or a hybrid steering shaft to use the sn95 rack, let me know as I am making them to sell, or I have threads on how to make them if you think you can.
    Bill likes this.
  3. Bill

    Bill Well-Known Member Staff Member Donator

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    Really good answers!

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