1969 mustang mach1 428 cobra jet 200k miles needs rebuild or replace thinking of putting a Lsx crate motor makes more power cost less anyone done this ? Thanks
You want keep something like that stock.
Worth more.
Tester
2 Likes
Is it a '69 or a '70? Either way, keep it stock, if it’s the original block. Is it?
1 Like
It doesn’t matter what it’s worth unless you’re selling it. Pull the original motor and bag it. Put in what you want as long as you’re not chopping stuff to put it in. Enjoy the car. If you decide to sell, either put the original engine back in, or include it in the sale.
The swap might make Ford purists faint…but the LS is much smaller, lighter and more powerful than an FE big block Ford. Pull the original engine, trans and driveshaft. Bag 'em and put them away.
Use a compatible GM transmission, build a custom driveshaft, build custom engine mounts, buy a computer and wire harness and drop it in. You might need a front sump oil pan and pickup, not sure. You should be able to purchase a new fuel tank already set up with a fuel injection pump and return line. Or mount an electric fuel pump and buy a 4 barrel manifold and carb. You will still need an ignition computer but MSD sells one.
Rebuilding the FE would be cheaper than this swap is going to be.
1 Like
I’ve heard of it being done, but exclusively to I6 models or more common 289 hardtops. You typically don’t do this with the more desirable models. Nobody is LS swapping a 69 Mach 1 with the 428. I have a feeling that we’re being trolled again.
I’m clutching my pearls as I type this 
3 Likes
Clutching my pearls is new to me, is that like the family jewels, not that that makes any sense either.
This is a special, rare Mustang. If you want a Mustang with a Chevy V8, spend a bit on getting this one in shape, sell it for $$$$, then buy a plain 302 V8 Mustang and hack away. You’d probably come out money ahead.
3 Likes
With a rare and valuable car like this it would be utter foolishness to replace the engine with a crate motor. If you were sitting there with a gutted rolling chassis I might go along with the crate motor but would never agree with butchering (the way I feel) an original.
3 Likes
I’m wondering if we’re dealing with a troll, this question is so off-the-wall.
5 Likes
For the record, I did a quick check on e-Bay. 1969 Ford Mustang Mach 1s are going for asking prices between $42,000 and $109,000. There is a wide variance in equipment involved, most are at least ostensibly in good shape. Given the potential value of this car, I would agree with the majority of the responses and try to keep this car as original as possible. To my thinking, your first step would be to have a reputable appraiser take a look. A $40K car would be a much more likely candidate for the engine swap you have in mind than a $109K car. Your decision, you have to be happy with it, but it’s better to be informed than not.
Note that most of those have the 351. The $109,000 car is a 428 CJ.
Here’s what “Cobra Jet” is worth on Bring a Trailer completed auctions: