71-73 engine swap

Discussion in 'Classic Mustang Specific Tech' started by hossdoc, Jun 25, 2009.

  1. hossdoc

    hossdoc New Member

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    Is there anyone out there who has done the 4.6 or 5.4 engine swap into the 71-73 body? I know on the pre 71's lots of shock tower surgery is required to accomplish the swap. Is this the case for the big boddied 71-73?
     
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  2. hossdoc

    hossdoc New Member

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    That's what I was afraid of....There is so little intrest in this body style that no one has tried this swap. Let me try this a different way. Can anyone give me the dimensions of the 4.6 2v, 3v, or 4v? What is the maximum width of the engine valve cover to valve cover? What is the height of that maximum width from the motor mounts and the oil pan rail? What is the length of the engine from the water pump to the bell housing?
     
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  3. Gud T.B. Blown

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    I think part of the reason this isn't more popular is that there are no performance gains to be had. They came with 460;s from the factory and even a modestly built 460 will make more hp that either a 4.6 or a 5.4. with a blower for a lot less $$$ and no surgery required.
     
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  4. rbohm

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    the 71-73 stangs have plenty of room under the hood for a 5.4 mod motor if you choose to go that route. but as pushrod power indicated the 460 can make a ton of power with mild mods, 500hp easy with a decent cam, intake, and ported exhaust ports. if you want more you can stroke the motor to an easy 514ci and make even more power.
     
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  5. hossdoc

    hossdoc New Member

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    Pushrod Power: To the best of my knowledge the 71-73 never came with a 460. The only engine options listed in any of my reference guides; 250 (6c), 302, 351, BOSS 351, and the rare 429CJ. I had heard that the 71-73s were designed with the BOSS 429 in mind but never got the engine. I had figured that if a 429 fit with no mods that the new mod motors would be no issue. I wanted to verify that before dropping any money on one. I am building a street/open track car and don't want all the extra weight of a big block up front. I am sure a pushrod would be cheaper in the long run to build from the ground up but am still kicking around the possibility of efi and eventually a turbo. Just checking all my options. Thanks for the input though.
     
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  6. woodsnake

    woodsnake Active Member

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    Where does a person drive a" street/open track"car?
    Is that like a solo I or II event?

    71-3 mustangs are kind of big cars to go racing in, especially around a corner...
     
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  7. hossdoc

    hossdoc New Member

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    I didn't say I was going to compete in any particular race curcuit. I have neither the time nor money in my life for that. However, too big to go racing around corners??? Well, don't tell that to Brion at Dark Horse Racing. He successfully competed in the AI series with one! I am just hoping to hit one of the two local road courses in my area as often as I can on open weekends etc. Besides, there are tons of guys that carve corners in cars that are equally as large. Go check out pro-touring some time. I am just looking to a bunch of fun with this car.
     
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  8. Gud T.B. Blown

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    You are correct that the 460 was never originally installed in the 71'73 but the 429 and 460 are the same block and are externally the same size.
     
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  9. hossdoc

    hossdoc New Member

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    OK. Now that we have established that the 460 will fit...Can anyone compare the dimensions of the 460 to that of the 4.6 or 5.4s?
     
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  10. rbohm

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    what part of
    do you not understand?
     
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  11. hossdoc

    hossdoc New Member

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    rbohm: No one has come forward claiming to have placed either the 4.6 or 5.4 in these cars since my original post on the topic. You state that there is "plenty of room". I have given you the benefit of the doubt on this point. But before I drop a dime on a mod motor I require proof that it will fit. All you have to do to convince me is provide me with the exact dimensions of the mod motors previously mentioned, point me in the direction of someone with this information, or compare the exact size of these engines with another engine that I know will fit in the car. I want to know what the clearance is going to be at the shock towers, front crossmember, fire wall, and steering components. I have learned to be skeptical of opinions which lack the tech to support them.
     
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  12. rebel65

    rebel65 Member

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    early stangers go for a Mustang II front end to fit modular motors, really haven't changed since 1991( i know there are some differences but for fitment purposes i mean ), if you already have a Mustang II i don't know why you would have trouble fitting a motor into a front end people use specifically for that application.
     
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  13. StangDreamin'

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    Yeesh! 5 Seconds on Google.....

    ...netted me THIS



    Now, two minutes later and four entries down in the same Google search page gave me THIS ARTICLE; which somehow shrank the Cammer engines. :shrug:

    Does that work for you?
     
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  14. hossdoc

    hossdoc New Member

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    Stangdreamin: Thank you. Those were exactly the specs I was needing to make my decision, especially since it would appear that no one has gone down this path; at least that I can find.
     
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  15. rbohm

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    hossdoc, if you were looking to swap a 460 into your big body, it would be easy since it is a front sump pan engine. the mod motor is a rear sump pan engine, and you will need to make many changes, including modifying the crossmember, moving steering components, etc. raw specs are not going to help you except to know that the engine will fit in the space provided. the 4.6 mod motor has been installed in 67-70 mustangs and cougars without removing the shock towers, but there were still many changes made to fit the engine. the 5.4 is about the same width as the 460, and about the same height, thus you can fit the engine in the engine bay. this is the fun thing about swapping engines that were not designed for the car, modifications have to be made, and the first few swap are going to have very little information available.
     
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  16. bnickel

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    also keep in mind that a mod motor weighs almost as much as a 429/460 and dimensionally the dohc motors are as wide as or wider than a boss 429. there is really no advantage to putting a mod motor in any early mustang, that i can see other than you will have a newer motor with more plentiful parts in the wrecking yards, especially in the next few years as the old ford pushrod motors will become less frequently seen. that said there will always be a good supply of pushrod cores as long as there are cars that use pushrod motors on the road.

    i will say however that i have been seriously considering doing this very thing to a big body mustang or cougar vert for my daughter at some point when she gets up to driving age so she'll have a nice cool old car with a modern dependable drivetrain that she can drive without having to worry about something breaking down
     
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  17. yeloxr7

    yeloxr7 New Member

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    Then you can be a pioneer in this field......
     
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  18. rebel65

    rebel65 Member

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    i think this is the motivation for most people who would do this swap, aside from getting a 5.4 L mill to get insane hp with modern street manners and pretty good mileage is also something that is attractive to me, and i know that you can put an efi system on a 351w and turbo or supercharge it or a stroked 5.0 and turbo and have good street manners. but i think a turboed 5.4L mod motor with some 4 valve heads would just be peachy :).

    if you want to go for an easy swap with 'proof' that mostly just drops in without the
    "Well how am i going to make this work"
    just go with a 460 or a stroker :O that would be awesome.

    if not, make some proof :D
     
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  19. hossdoc

    hossdoc New Member

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    Can you simply convert the mod to a front sump pan? What is your best guess as to the modifications required to the crossmember and the steering components? A little nip and tuck to the crossmember is no real issue, however reworking the steering system is not something that I want to trailblaze. I know just enough about suspension and steering geometry to know that I am not the one for this task. If there were a front steer rack and pinion, double A arm, coilover setup on the market for this car I would soooo be there! Oh Griggs, where is your conversion kit for the '71????
     
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  20. 2+2GT

    2+2GT Well-Known Member

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    Oh boy. This is a welded-in complex structural part of the car.
     
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