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engine swap for a 1968 Mustang coupe - will a 390 work?

44K views 85 replies 36 participants last post by  GypsyR 
#1 ·
Hello all,

i have a 1968 Mustang coupe that i am restoring. i am a newbie and doing everything myself (paint, body, and so on).

i purchased the car with a 289 engine and automatic transmission - i believe it is your standard C4 transmission.

here is a link to my documentation site:

https://picasaweb.google.com/geeky2

someone has asked me if i want to buy their 390 engine and swap out my 289 engine (that came with my car).

1) will a 390 fit in the engine bay of a 1968 mustang coupe?

2) he wants to sell the engine for 150.00. is this a fair price?

also - are there any other considerations i need to take in to account?

for instance - do i have to find a new transmission to fit the 390 engine?

ANY advice or guidance would be greatly appreciated.

thank you,
mark
 
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#2 ·
Yes the 390 can fit in a 68. Thank god you didn't say you had a 65-66 because you'll get the 3rd degree from everyone about having to cut out stuff to make the engine fit. As for being a fair price, sounds fair to me. Not sure about anything else. Not too familiar what the needs for 390.
 
#3 ·
Yes it can be done, all the parts to do the swap are available. The 390 has a different bellhousing bolt pattern than the 289. Most auto trans for 390/FE engines were the C6. There maybe a bellhousing for the C4 that bolts to a 390, but the C4 will need to be upgraded.

I put a 390 and 4 speed in my 67 coupe. Starting from scratch, buying all the necessary parts for the 390 adds up quickly, but IMO its was worth every penny.
 
#4 ·
$150.00 for a running 390 ? sweet price i just paid $100. for a rebuild able long block 390 and thought i got a deal . i 'd buy it even if you decide you don't want it ,you can turn a profit easy . just make sure it is a 390 not a 360 or 352 .they all look the same from the outside, only diff is bore and stroke . 390 is 4.05 bore and roughly 3.75 stroke
you can measure stoke with a wood dowel thru the spark plug hole 3.50 stroke =360
 
#5 ·
Sorry, I'm not going to jump on the 390 bandwagon.
Antiquated, heavy and so-so mileage. (I'm now zipping up my flame proof suit)
You'd be better off building a 289, 302 or stroker engine.
By the time you upgrade everything (like you really should) to run
a 390, you're better off going the other way.

A well sorted 289/302 with a C-4 is more than a match for a 390 with
a C-6..... any day.
 
#9 ·
+1

Stick with the 289, it is a better engine for the Mustang. The 390 was a truck/boat/"full size" car engine. The 289 is a sports car engine with racing heritage. The first thing Carroll Shelby did with the 390 was remove it from his cars. ' Nuff said.
 
#6 ·
The cylinder heads for a 390 in a Mustang are different than the more common ones used in trucks and full size fords. The difference is in the number of bolts for the exhaust manifold. Full size fords have 8, one above and below each port.
Mustangs have 14 I think. To run the stock exhaust manifolds for the Mustang you MUST have the correct cylinder heads. If you are willing to run long tube headers you can use the more common 8 bolt heads.

Bottom line, the 390 is a bolt in engine in the 68 Mustang. But it uses almost none of the parts you all ready have to bolt in. If the 390 came from a Mustang and you could source all the parts in one place it might be worth the hassle. It depends on what you want out of your car.
 
#7 ·
Mustang was widened fot 67/68 (same width as the first Cougar which was 67) specifically to allow the 390 engine(s). Many 67 and 68s were built with the 390.

The 390 was used in many Fords including the T-Bird, LTD most were manual tranny or
C6 tranny and depending on application accesory mounts as well as bell housing may be different as JDM said.

Make sure you and or your mechanic has checked all these "details". It's not just a simple 1 for 1 swap.


Slim
 
#10 ·
If you're not a big block fanatic (yes fanatic) I'm another long time Mustang nut wearing a flame resistant suit. The 390 was an old engine in 67 but brute power to compete with Camero. If you like to do your own underhood work you may soon dislike it unlike you love knuckle busting challange of wrenching it tight places.

The 302 and 351 are "small blocks", easy to work on and less antiquated.

I'm a converted small block fan. In 55 Chebby introduced the "modern" small block V8. AIRC it was 263 cube lightweight valve train, big valves and revved like crazy!

Around 61 Ford had their version of the lightweight small block. The 260,289,302 and 351 are versions of that design.

I would recommend you evaluate carefully before jumping into a 390 swap. Where is it from, what condition, do I really want the big block, what all needs to chance etc.

Slim
 
#11 ·
Save yourself alot of headache and build yourself a small block to put in the car. It will handle a lot better, its alot lighter, easier to work on, cheaper to build. FE engines are a different animal all together. If you dont know anything about them (like most machine shops) its better to stay with the 289 or windsors. You will have all kinds of issues with headers, having to change the coil springs for the added weight, and upgrading the cooling system to keep it cool. Im not knocking the 390 by no means. I have a 1969 Mach 1 with a factory 390. I love the car. Just trust me on this one and stay with the small block if thats what it came with.
 
#14 ·
Yes.



And a "well sorted" 390 will go 600+ HP and massive torque, without too much effort. So depending on the "match" strip or track, results may vary.

Check out Suvival Motorsports for what you can do with an FE...

Survival Motorsports Home Page
 
#16 ·
Excuse me for apparantly misreading the OP. My impression was he was asking if the 390 swap was doable, will it fit and suggestions/advice.

Didn't read anything about drag racing, track racing, which would handle better etc. I gave my honest opinions. Note I've often said lime gold is my favorite.


Slim
 
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#17 ·
+1 on that. Is the swap doable? Absolutely. Cost efficient? Well that depends upon budget and purpose. There are pro's and con's to doing the 390 swap, the OP will have to decide if the challenges of doing the project (versus staying with the SB) are worth it. FE engines have great curb appeal at shows, enough torque when built properly to tow a semi trailer up Pikes Peak or melt tires/pavement at will, but handling is heavy at the front with significant understeer. Power steering is almost a necessity with an FE unless you have muscles like Arnie has (or had), and the springs, rear end etc. will need changing out, the list goes on...
 
#18 ·
Hello all,

WOW!

this forum and the experts that sit on it, are FANTASTIC!!!! i am lucky to have found this site ;)

thank YOU ALL for the great feedback.

you have given me a great deal to think about.

i will post back when i have processed all of this info and made a decision.

thank you again,
mark
 
#21 ·
Here is my advice, and I am a dyed in the wool FE guy willing to make any 390 scream

Do the stock motor and learn to restore this car first. Get it done, learn to enjoy it, and if you decide to go 390, then you have two choices, swap or sell a running car and buy a 390 car.

This being your first resto, that alone will add to your work, do the small block, make the car a part of the family, then make a decision when its done. The FE is almost a weekend swap later on when the car is complete
 
#23 ·
best advice in the entire thread.

Yes, it will fit, yes it will run good, it will handle like its got the extra weight in it, etc.

i would go buy the 390 since it appears to be a decent price, put it in the corner and start buying stuff for it to build it how you want.

no reason to rush to put a stock motor in there.
 
#24 ·
OR you can buy the 390 engine and if it's in really good condition, turn around and sell it for more money! :idea:
 
#25 ·
Unless the car was originally a 390 or 428 car, it's going to be a headache for a novice to go from a 289/302 to a 390/428. When I switched the 302 out of my first Mustang to a 351 Cleveland, I ran into all kinds of problems. Some of the problems were, had to change the radiator, get all the correct pulleys for the 351, obtain the accessory brackets for the power steering pump and alternator, had change the exhuast, change the transmission, get a different transmission crossmember, new driveshaft, and a host of other issues. You'll have to change all those things and more.

Personally, I'm not impressed with the 390 as a performance engine. Yes, I know they can be made to run fairly well. I had friends with 390's that ran pretty good. But they are a very archaic design and don't have near the aftermarket support of the Ford small block. And that was before the aftermarket support that the 289/302/351W engines have today.

I have a 351w stroker (393 cubic inch motor now) that puts out around 600hp. It weighs several hundred pounds lighter than a 390 (even with aluminum heads and intake). My motor would run laps around any 390. I have several hundred pounds less on the front end which makes my car handle much better. Parts are cheaper than the 390 (stock and aftermarket).

So unless there's a really good reason to go with a 390, I'd stick with a 289/302, or even a 351w. But even with the 351w you're going to have to change things.
 
#26 ·
Mustang rebuid

Took a look at your progress site w/pictures. If you decide to use the 390, your more than qualified to get it done right!

All the bad press I've seen on the 390 and FE motors in general is misinformation that grew over the years, even comments on engine weights are usually grossly exaggerated.

The only real truth I've seen is that in general it costs more to build an FE than many other motors.
 
#27 ·
All the bad press I've seen on the 390 and FE motors in general is misinformation that grew over the years, even comments on engine weights are usually grossly exaggerated.

The only real truth I've seen is that in general it costs more to build an FE than many other motors.
Agreed! My 428 with the use of aluminum components is within a 100 lbs of my stock 289. With stock suspension up front, I sure can't notice any handling difference.

I will tell you that it's now a lot more fun to drive! ;)
 
#29 ·
Lula,
You totally missed the point. The point is: FE's don't weigh nearly as much as most people think. A quick internet search yield FE engine weights of 650 -680 lbs depending upon the source. A small block 289/302 weighs around 460 lbs. Not sure where you come up a 500-lb difference.

My other point was that with 43 year old suspension technology/design, nobody is going to notice an extra 100 lbs in the front end.

390's and 428's aren't all that different. Same block, different stroke & bore. The same mods to my 428 could be applied to 390 and yield similar results. Power will be down a little simply due to fewer cubic inches.

We are getting off track from the OP's question though; he simply asked if a 390 would fit and if $150 is a fair price. The answer to both questions is "yes".
 
#31 ·
Lula,
My reading comprehension is just fine. I understand the point that I made, but apparently you didn't. I tried to clarify it in a civilized manner but it appears that you are just looking for a pissing match. Count me out.
 
#33 ·
Drop in a 460 with an Edelbrock Top End Kit and you'll have a Super reliable, low RPM ride with 500 + HP/TQ,.....hold the %$@* on and enjoy!
 
#36 ·
Only factors I see here is cost. FE's can be lightened with aluminum components to make the difference less than throwing one of your kids in the back and will spin just as fast as a SBF. The sound and torque are both incredible. Of course, you can always build a 427 inch small block if you'd like. Either way there's no replacement for displacement.
 
#38 ·
I for one like the idea of the FE in the 68 Mustang. Small block cars are just done to death. Congrats on some originality to you! Some of the things you will encounter with this swap will be:
1) cylinder heads (14 bolt type)
2) exhaust manifolds / headers
3) if using a C-6 (must come from another intermediate car or modify floor pan / firewall)
4) C-6 trans crossmember
5) driveshaft
6) 9" rearend
7) front and rear brake upgrades (drum dimensions are different)
8) front and rear springs
9) cooling system (radiator / shroud / mounts)

There is a some weight differences as mentioned, but don't let that deter you. My dad is an original ower of a 1966 390GT Fairlane with manual steering. His steering does not require two hands like some people post try to make you believe. He can steer his car with only one finger. One other note, if done properly, you can get fair milage out of a big block. (in my own case, 1966 Fairlane 390GT clone, 475 horsepower, 618 ft lbs torque, 24-27 miles per gallon, and no aluminum heads or intake either!)

Good luck with your project!!!

Good luck with your project
 
#42 ·
It weighs several hundred pounds lighter than a 390 (even with aluminum heads and intake). My motor would run laps around any 390.[/qoute]

Really? "Several", like 300-400??

The 351 only weighed 70 pounds less than a 390 from carb to pan, less bolt-ons. 530 vs 600 per Ford. So I seriously doubt "several" hundred pounds savings is realistic (or you got your 351 down to about 200-250 lbs). Maybe 100... maybe a little bit more, with similar alloy head/intake replacements as sizes are close, but a bit larger intake on the FE so a few pounds more... (but it sure sounds good with no actual evidence!)

Its about more than the weight of the engine, 427's weighed in at 680 (must be a ship anchor!) yet are oddly desireable! Otherwise T codes would rule (lighter is better right?) :)

And "any" 390? FE's pushing well over 600Hp (some carb'd over 700) and massive torque, pretty bold... but may be true. But there are lots of after market goodies to pump up a FE these days. A bit more cost, yep, but not really staggering differences.

351 to 393 stroker kits.... $1200-2000
Ford Engine Kit - Ford 393 Stroker Kit, 351 Windsor Stroker

390 to 445 stoker kits... $1900-2300
Survival FE Engine Kits

So in the long run of a restoration not a real big difference in cost to build a big FE over a high performance small block. And to me the bling factor when you open the hood is worth it.

The mythology and legend against the FE is ingrained, but with some new parts they run quite well and give very good power to weight and great torque curves with the right build. A great engine, no, (but is the 60's 289 or 351 really top notch either in original form?) but not as bad as many suggest...

They will all go down the road at a fun pace... but if you want a race car a Mustang is a bad start if cost vs. performance is the goal!! Far better cars for far less $ available if the lowest lap time is the end game...
 
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