Engine Getting ready to build one

Discussion in 'Classic Mustang Specific Tech' started by Restomodboy, Mar 6, 2013.

  1. Ok, so I have a 67 shell that I bought off craigslist, pretty straight body, needs interior, engine, trans, and rear quarter glass.
    I have sorted the glass problem. One of my friends works at a shop and can get me one for free.
    Interior will be stock, I am in the process of restoring it to its former glory.
    I will probably re-gauge it and do a hidden stereo.
    I have a 9in from my last prerunner project and some torq thrusts that came with the car.

    I am having a dilemma with the engine, mostly indecision.
    I just need some thoughts on an engine.

    I know the 4.6 and the 4.0 pretty well.

    I am not sure what to get but I know that I do not, I repeat, DO NOT want a carb.

  2. Its a rabbit hole I tell ya! How far down it do you want to go? A mod motor wont fit with those shock towers in the way. Even a 302/5.0 with that big ole intake gets in the way of handling performance due to the sacrifices made in the way of bracing. This rarely has light shed on it, but its true. I see cars with those big cast manifolds and no proper bracing and just chuckle. And no, heim joints are not a proper way to build a brace to get around those ginormous intakes.

    At issue for me is proper underhood support when you run a taller than stock motor or a EFI that eliminates proper bracing. The Shelby cars and the cars sent overseas had an "Export Brace" installed that did wonders for chassis stiffening and if you install a motor that sits up to high you can sacrifice bigtime and have a car that wallows because the front suspension mount locations do not stay put.

    Even if you remove the towers to fit a MOD motor and go with a MII setup the front will then flex, possibly even more than a car with zero bracing. Many think that cutting out shock towers and putting a heavy cross beam to mount the motor to is all good and fine, I dont. The cars floor & firewall where the frames connect is not designed to deal with those downward loads or twist...When you head into a dip on the track or on the road the car will have the sudden desire to fold where the frame meets the toe boards. Sure, the motor is mounted really well to something, and in a straight line it can pull the car along fine, but its those damned pesky dips and off camber curves.

    Someone will be along soon to tell me that the car they have has no such issues and that a MII setup works fine. But, I never really see those cars at a racetrack or cone race event without serious bracing and sometimes even a chassis under the car.

    Sorry for the rambeling. Here is a great thread on how to build a $5000 budget mustang... It may give you some ideas!

  3. I gave up on that thread when I saw the ls1 engine mounted.......
    Why not look into an EFI 5.8? (351W) I just do not understand the desire for a modular motor in an early car. Too many better push rod engine options available...
  4. I also would go with the 5.0 or 5.8 engines, fit good, and you get to keep the towers, and if you use a FI setup that uses a standard type 4 bbl intake, you can still use the export brace.
  5. I am heartset on a newer motor, just a lot less work for a lot more power.
    I just need advice on bracing for a different motor.
    How do I make the car stiffer??
  6. Well, it's like Fstbk said, with the mod motors you need to remove a lot of the structural parts in the front. The question then becomes where can you put it back. I haven't really looked at any mod conversions up close, so if you are sure that's the direction you want to go, I'd suggest doing a lot of research. Look at what others have done, and look to see where you can add more support. Just know it will be a lot more work, and you are going to have to make a lot of the parts yourself.

    Edit: One more thought, think triangles. A triangle is a much stronger structure than a square.
  7. With the amount of custom fabrication required for the entire car, rust repair, etc. one would think a 351 setup with a custom intake to allow for a forward facing TB and one that would clear the export brace would not be that big of a task.
  8. if you are really wanting to swap a later model engine into an early car, then the 4.6 is the way to go. and you may as well step up to the four cam mod motor and do it right.

    you might be able to get away with notching the shock towers and keep the stock suspension, or you can remove the shock towers and go with a mustang ll suspension system, but a much better way to go is the RRS strut front suspension. you get to keep the shock towers, just in heavily modified form. that way you maintain the original suspension load path, and still have plenty of room for the mod motor.

    and while you are at it, upgrade the rear suspension to a torque arm design with a panhard bar or watts link and coil over shocks.