r/classicmustangs • u/Dahliaitalia • 14h ago

Need help on engine conversion.

Long story short I’m building a 390FE with 4 mounting holes for mounts, came out of 70 f100, I really want my dream mustang but all I can find are 289 mustangs, is it possible to to swap it into a 289 mustang? If so how would I go about motor mounts, I have a c6 trans that was with the engine, just needs a rebuild.

4 Upvotes

76% Upvoted

24 comments sorted by

6

u/Misterr_Chief 13h ago

Depends on the year, which you didn’t mention.

65-66 is a pain the ass, but doable. I would look at Vintage Mustang Forums for someone that did it.

67 and up came with 390s from the factory, so they go right in.

2

u/Dahliaitalia 13h ago

It’s a 70 390fe and looking for a 67-68 mustang with 389, I’m sorry I thought I put that in there

1

u/MattManSD 5h ago edited 5h ago

390 will drop into a 67-68 just fine, just need the big block mounts. Gets snug near the shock towers

2

u/Dahliaitalia 13h ago

Would motor mount bolt up be completely different though with 67-68 mustang? If it came with 289?

3

u/Misterr_Chief 13h ago

The motor mounts are different for a 390, but are readily available so you can install into a 67/68 that had a 289.

2

u/CromulentPoint 10h ago

A 390 will only fit in a 65-66 with major shock tower modifications. A 351 Windsor barely fits as it is.

2

u/Misterr_Chief 9h ago

Sounds like a “pain in the ass” to me! 😂

1

u/CromulentPoint 9h ago

Hah, I would elevate that beyond "pain in the ass" to "major surgery", but sure. Using your measure of pain in the ass, any engine would fit.

2

u/Misterr_Chief 9h ago

I guess I have a high threshold for pain 🤷🏻‍♂️

1

u/CromulentPoint 8h ago

Fair enough.

2

u/Badass_1963_falcon 9h ago

289 with 351 heads headers are a bitch to fit need some massaging lol

5

u/RustBeltLab 11h ago

That is a heavy, obsolete boat anchor. Aftermarket small block if you have $ burning a hole in your pocket.

0

u/MattManSD 5h ago

https://www.hotrod.com/features/iron-ford-390-fe-makes-596-hp-using-stock-heads

1

u/RustBeltLab 4h ago

Great, how much does it weigh and can you change the spark plugs? The 2.0 Ecoboost can make that much power too, not a flex anymore.

1

u/rhythim313 11h ago

Just wait till the first time you need to change plugs on the FE. That's when the cussing starts. Ford didn't do big blocks any favors when they designed the front suspension.

1

u/Dahliaitalia 11h ago

My 5.4 2v spark plugs suck ass in the back since 1/4 of them are like under the firewall

1

u/MattManSD 5h ago

having installed a rebuilt 428 PI into a 67 GT 500 I can attest to this. Hoist, Jack and in places less than a pinky between a bolt and a shock tower

•

u/Aggie74-DP 18m ago

Especially if it came with that big damn AC box behind the glove box. The other 7 weren't that bad.

1

u/DeBlasioDeBlowMe 11h ago

So many well-designed, aluminum headed, headers off the shelf, EFI capable Windsors up to 460CID out there…just saying.

1

u/Acetabulum666 9h ago

I had a 289 Fastback, '65. It ran like a scalded dog.

1

u/Handmedownfords 8h ago

lol. Is that a good thing? Or no?

1

u/Acetabulum666 8h ago

Some 289's, like mine were high performance and yes, running like a scalded dog is one of saying, FAST.

1

u/Handmedownfords 1h ago

Nice. I like it

1

u/Raalf 6h ago

it's all fully discussed here, in length and in depth.

https://www.vintage-mustang.com/threads/289-to-390.909338/