391 swap into foxbody

Stangfox · Jul 16, 2020

Hello im new to this forum and I was wondering if anyone has swapped a 391ft engine into a foxbody? I recently got ahold of a 391ft or 105 mirror engine and I've read good things about the block. I know people will say I should of just stuck with the 5.0 or a 351w but I'm trying to do something different. Just wanna know if it's worth it to build or of i should just sell it and get another engine

Ryuk · Jul 16, 2020

I'm not fond of changing my passenger side spark plugs on a 302. I can't imagine how that would be on a big block.

Stangfox · Jul 16, 2020

Lol do you really think it would be that bad

Werecow91 · Jul 16, 2020

Mines got a 351M and I've got 1 plug on the driver's side I gotta change from under the car!! No room from the top because of the brake booster!!

Stangfox · Jul 16, 2020

Well dam now I'm kinda starting to regret getting that 391 engine lol

Stangfox · Jul 16, 2020

But I've heard of people swapping bigger engines into fox bodies though

KRUISR · Jul 17, 2020

Stangfox said:
I recently got ahold of a 391ft or 105 mirror engine

Do you mean a 390 FE series engine? Also, what is a 105 mirror engine?

In either case, unless you are building something for nostalgia drag racing or something, a big block like that will likely handle horribly. Far better to spend money on 302 or 351W based power plant (depending on your goals for the car).

As far as big block in a fox, there was a kit (header, oil pan, motor mounts, etc) for a 460 back in the day. Don't see many of those cars around anymore. I remember a feature article in one of the magazines of one, an '81 with the 2-tone paint and 14" wheels with the factory turbine hub caps. The only thing not stock 4-cylinder looking on outside was a hood scoop to allow clearance for the carb.

CarMichael Angelo · Jul 17, 2020

A 390 FE engine isn’t worth the hassle to move it, much less actually install it. The bellhousing pattern forces a C6, and is really rare, the heads SUCK for flow, with an exhaust port that is full of weird bumps and obstacles. The cast iron intake ( which is so wide, it actually extends to under the valve covers) weighs so much you can forget about lifting it over the fenders to install it. It’ll have a front sump pan with no alternative aftermarket option, and Zero headers that’ll fit.

And after all of that...it’s still a giant pain in the ass to change the plugs on.

are those enough reasons to move on?

Stangfox · Jul 17, 2020

10-4 guys I think ima sell the engine and keep looking for a 351w instead

Stangfox · Jul 17, 2020

And the 391 is from the ft family for the bigger heavy duty truck engines like the ones from uhaul

General karthief · Jul 17, 2020

How to Identify a Ford 391

Ford's 391 cubic inch big-block, manufactured from 1966 to 1978, is a member of the FT truck engine series --- closely related to the more common FE-Series. The FT-Series consists of the 330, 361 and 391 cubic inch engines and have differences related to their truck usage. FE and FT engines are...

itstillruns.com

Boat anchor.

rbohm · Jul 18, 2020

Stangfox said:
And the 391 is from the ft family for the bigger heavy duty truck engines like the ones from uhaul

yep basically a heavy duty version of the 390FE engine. the biggest thing is the crank in the FT engines are forged where as in the FE engines tehy are cast. you will have to do a bit of machining to the crank snout if you want to use the passenger car balancer.

OP my advice would be to keep the 391, and build it for a truck that would do some heavy towing for you, find a 351w and stroke it out to 393 or 408, or do like i want, and swap in a 460.

Steel1 · Jul 18, 2020

In the early 70s my mom had an old Mercury 4 door (can't remember model) with a 390 .
I remember thinking it was cool to tell my friends it had a 390 v8...lol what did I know.
My sister's boyfriend at the time ,who was pretty knowledgeable about cars , said to me "that things a boat anchor" .
So my quest to learn something about cars began.lol

rbohm · Jul 18, 2020

in stock form the 390 is a decent enough motor, and it is capable of so much more. i like the FEs, though i prefer the 385 series big blocks more.

Willybill32 · Jul 18, 2020

Eventually Ford punched the 390 out to 406 in '62, then to 427 in '63/'64. They were not overly successful against the Chevys of the day...

Ryuk · Jul 18, 2020

It goes to show how things have changed. In 1969, Ford had a 427, a 428, and a 429 and all were different block designs.

General karthief · Jul 18, 2020

The 427 and the 428 were FE blocks and the 429 was the 385 series.

CarMichael Angelo · Jul 18, 2020

General karthief said:
The 427 and the 428 were FE blocks and the 429 was the 385 series.

You tell em GKT.

CarMichael Angelo · Jul 18, 2020

Willybill32 said:
Eventually Ford punched the 390 out to 406 in '62, then to 427 in '63/'64. They were not overly successful against the Chevys of the day...

I believe that to be an inaccurate statement.
Chevy didnt even try to run in Lemans..Ford not only did that, but won that race with a 427 for 5 years straight from 64-69.
TASCA ford kicked ass in the early 60's in Afx with a 427 As did others like Don Nicholson, Gas Rhonda, and the Holman Moody team driving T bolts powered by 427 SOHC ( cammers).
THAT engine was such a heathen, the weenie Bow tie teams in NASCAR bitched so loudly they got that engine banned, which forced it into usage in NHRA.
Follow that up with the factory domination when the 428cj showed up in 1968 as a CobraJet, and SSA, and SS got put on notice that Ford wasnt dicking around. Through the late 60's, the 428cj held C/stock auto in a Mustang.

rdharper02 · Jul 18, 2020

Someone said 390? Not my favorite, but a heck of an improvement over the 360 FEs

391 swap into foxbody

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my rearend will smell so minty fresh,

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wonder how much it would cost to ship you a pair

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But at least it's tight!

I love your drawers

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my rearend will smell so minty fresh,

my rearend will smell so minty fresh,

like kicking myself in the junk

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