Will 1971+ 340 Exhaust Manifolds fit in a 67 A-body?

[barracuda-67]

Hi Mopar gurus -
The 1971+ 340 manifolds look larger than the 1967-70 ones. Will 1971+ fit into a 1967 A-body (a Barracuda) with power steering and power brakes?

1971+ 340 manifolds look impressively big, and the driver side seems to rise higher, as in this posting:

[FOR SALE] - 1971-1974 Abody 340 exhaust manifolds

For sale 340 manifolds from 1973 340 duster nice shape no cracks or repairs...hardly any pitting...passenger side heat riser still works...$375 plus shipping..PayPal friends & family or postal m/o...ty fabo...

www.forabodiesonly.com

The 1967-70 340 manifolds look smaller, as in this posting:

[SOLD] - 67-70 A body 340 HP Exhaust Manifolds $550

67-70 A Body 340 HP Exhaust Manifold. No cracks or repairs. No heat riser.

www.forabodiesonly.com

So... Does anyone know, will the later 340 manifolds fit a 1967 with power steering and power brakes?
Thanks in advance!

 

[Professor Fate]

Yes.

 

[Kern Dog]

Since all 1967-76 A bodies have identical chassis and engine bay widths, of course these will fit.

 

[Scampin]

The 67-70 are quite a bit better performance wise than the 71 up.

 

[Scampin]

71 up driver's side only looks bigger because of the heat shield/stove mounting bosses.

 

[barracuda-67]

Thanks, @Kern Dog and @Scampin !

 

[Kern Dog]

The 67-70 are quite a bit better performance wise than the 71 up.

You'd think that but there isn't a whole lot to gain from the different exhaust manifolds.
Mopar Muscle did a test years ago on a MP crate 360, the 300 HP version.
They compared early 273/318 manifolds to 340 versions and the later 360 manifolds. The 340 manifolds made a whopping 7 HP more than the 273/318 stuff.
S E V E N horsepower on a 300 hp engine.

When I see people spend big money on 340 manifolds for a car that is not a stock restoration, I shake my head.
The 340 manifolds do look better and there will be a performance improvement but what made the 340 great was not the manifolds themselves. The 340 had more compression, better cylinder heads, a bigger cam and a 4 barrel carburetor.
Cheers!

 

[barracuda-67]

You'd think that but there isn't a whole lot to gain from the different exhaust manifolds.
Mopar Muscle did a test years ago on a MP crate 360, the 300 HP version.
They compared early 273/318 manifolds to 340 versions and the later 360 manifolds. The 340 manifolds made a whopping 7 HP more than the 273/318 stuff.
S E V E N horsepower on a 300 hp engine.

View attachment 1716427606

When I see people spend big money on 340 manifolds for a car that is not a stock restoration, I shake my head.
The 340 manifolds do look better and there will be a performance improvement but what made the 340 great was not the manifolds themselves. The 340 had more compression, better cylinder heads, a bigger cam and a 4 barrel carburetor.
Cheers!

wait, what? The 318 manifolds will bolt up to the 340 without leaking? I thought I read a thread which indicated the 318s wouldn't work.

I have 318 manifolds on the car now (plus have a pair of 273s!).

The ratio of (a lot of dollars) / (7 HP) is not pretty. If 318s will work I'll use them!

 

[Kern Dog]

The bolt spacing on all the stock LA series heads is the same so all LA series manifolds will bolt up.
The exhaust ports on a 340 are bigger so using a 318 manifold on a 340 will result in a port mismatch but with a gasket, they should seal just fine.

 

[harrisonm]

Yes it will work. Someday, if you get the chance, place your 67 Barracuda next to a 39 340 Barracuda with the hoods open. The engine compartments will look the same.

 

[66fs]

wait, what? The 318 manifolds will bolt up to the 340 without leaking? I thought I read a thread which indicated the 318s wouldn't work.

I have 318 manifolds on the car now (plus have a pair of 273s!).

The ratio of (a lot of dollars) / (7 HP) is not pretty. If 318s will work I'll use them!

I've run 66 273 exhaust manifolds on 72 340 J heads. No leaks, but I did port the exhaust manifolds except the bottom of the ports. If you are careful, you should not have a problem.

 

[AJ/FormS]

Just so you know
Log manifolds will kill the overlap cycle of ANY cam that you install.
This could mean just about NOTHING to you if running a 318cam in a 318 engine, lol.

 

[furrystump]

I think Scampin would sell his soul (again) to run pre 71 manifolds.

 

[4mulas]

100% agree with post #7. The performance difference between a 1970 HP drivers side and the next rendition (71 and up) manifold is negligible. The cool factor difference is huge though, which instills more confidence and that alone will make you faster. lol.

 

[DionR]

You'd think that but there isn't a whole lot to gain from the different exhaust manifolds.
Mopar Muscle did a test years ago on a MP crate 360, the 300 HP version.
They compared early 273/318 manifolds to 340 versions and the later 360 manifolds. The 340 manifolds made a whopping 7 HP more than the 273/318 stuff.
S E V E N horsepower on a 300 hp engine.

View attachment 1716427606

When I see people spend big money on 340 manifolds for a car that is not a stock restoration, I shake my head.
The 340 manifolds do look better and there will be a performance improvement but what made the 340 great was not the manifolds themselves. The 340 had more compression, better cylinder heads, a bigger cam and a 4 barrel carburetor.
Cheers!

Unfortunately, this is not a valid test. The best headers (TTI step headers) in that test only made 16 hp more than the 318 cast iron manifolds. The bottleneck wasn't the manifolds or exhaust, it was the flat OEM camshaft that ran out of breath at 4500 RPM. Do the same test with a 360/380 crate motor and I bet it would be different.

Not saying I know the 340 manifolds are significantly better, only that it is a bogus test that has been pointlessly tossed around for years. It didn't give any useful info and shouldn't be used to say anything at all other than on a 300HP crate motor they did "X".

 

[DionR]

Installing Exhaust Headers Into 300hp Crate Engine - Exhaust Blowout

Read on as we dyno test our installed exhaust headers and exhaust manifolds into our Mopar Performance 300hp crate engine. Read on for more details along with photos only in Mopar Muscle Magazine

www.hotrod.com

<Sarcasm> Just run the stock manifolds and single exhaust, based on that test </Sarcasm>.

I would say headers aren't worth the money and struggle to install either.

 

[Kern Dog]

Unfortunately, this is not a valid test. The best headers (TTI step headers) in that test only made 16 hp more than the 318 cast iron manifolds. The bottleneck wasn't the manifolds or exhaust, it was the flat OEM camshaft that ran out of breath at 4500 RPM. Do the same test with a 360/380 crate motor and I bet it would be different.

Not saying I know the 340 manifolds are significantly better, only that it is a bogus test that has been pointlessly tossed around for years. It didn't give any useful info and shouldn't be used to say anything at all other than on a 300HP crate motor they did "X".

You sure have a right to your opinion even though it is wrong.
The test was done on a mild engine which was quite representative of what many enthusiasts have. The 360/380 also had a low rpm power peak, though it was higher than the 360/300 version. I can post a rating once I get home but I recall that even the 360/380 peaked around 5400 rpms.
Who would actually stick with cast iron manifolds when their engine could make 400 hP with headers? Why intentionally handicap yourself? Good headers fit well and make power.
On an engine making 300 HP or less, that test is really helpful.

 

[DionR]

The test was done on a mild engine which was quite representative of what many enthusiasts have.

Sure, if you are going to leave the 2BBL cam in it.

Here are the specs I got from Bullet Cams when they ran my '02 5.9 cam through a Cam Doctor:

Duration @ 0.050: I/E 189*/194*
Lobe separation angle: 111*
Lift @ cam: I/E 0.273"/0.278"

Also, this enthusiast ran the stock 5.9 cam for a couple of years. It's not a performance cam, even if it gets the job done.

The 360/380 also had a low rpm power peak, though it was higher than the 360/300 version. I can post a rating once I get home but I recall that even the 360/380 peaked around 5400 rpms.

Yep, the article I found on the 380HP crate motor listed that same rpm. That's with a 288/292 cam, too. Pretty big, enough that I know of a guy that wanted a smaller cam. Maybe not the magical "6000 rpm", but I'm not sure I would say it had a "low power peak".

That same motor the manifolds were test on made like 50hp more with a mild 264/270 (212/218@0.050) cam. Just from the cam swap.

BTW, Holdener's video showed the hp peak at about 5100 rpm. And the stock motor peaked at 4100 on his dyno. A 1000 RPM peak difference seems pretty good to me. And he put in a mild cam. The stock cam is absolutely dinky.

Either way, a bigger cam would have moved the bottleneck around and maybe would have shown the results of the manifolds. That's why Engine Masters didn't use small motors, how can you tell if the results are valid if you aren't testing the bottleneck. I am sure not everyone had a 1000hp BBC to run a tunnel ram on, but a mild 350 wouldn't have given any meaningful results and made the show pointless. Just like this test doesn't give meaningful results.

On an engine making 300 HP or less, that test is really helpful.

Then apply the results to those situations. I swear it seems like every time I see this test brought up, nobody asks about the motor. But the test is applied like everyone runs a basic 5.9. No one asked in this thread what the OP has.

Most enthusiasts are going to put a cam of some type in it and at that point that test is pointless. Do you know what the 340 manifolds would make with a bigger cam? I don't, and this test doesn't tell us anything. The test is worthless to anyone that isn't going to run a stock 5.9, which is most of us.

And I would bet a stock 340 would lose more than 4hp if the 318 manifolds were swapped on. I would also argue that a stock low compression 360 with a 268/268 and stock iron heads would see a bigger loss than 4hp. But nobody knows (that I am aware of), because this test doesn't apply.

 

[65 Cuda 340]

Interesting how people can think early 340 manifolds are barely any better than 318 manifolds, but 67 383 A body manifolds (below, top) are 45 horsepower worse than B body 383 log manifolds (below, bottom).

 

[65 Cuda 340]

Factory horsepower ratings back in the day were NOT gospel. As much advertising as reality.

 

[Kern Dog]

Interesting how people can think early 340 manifolds are barely any better than 318 manifolds, but 67 383 A body manifolds (below, top) are 45 horsepower worse than B body 383 log manifolds (below, bottom).

The bigger the engine, the more airflow.
The difference between log manifolds to the HiPo on a big block is probably different than a 318 manifold to 340 on an engine 100 cubes smaller