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Exhaust Manifold Question
#1
The previous owner of my 71 M Code put 2V heads on rather than rebuilding the 4V closed chambered heads, apparently it was common since the 2V heads allowed the use of lower octane fuel and many believe it's improves every day driving experience by increasing low end torque.

In any case I'm putting 4V closed chambered heads back on it and was looking for a set of 4V exhaust manifolds when a friend told me he believes the car still has the 4V exhaust manifolds on it.

First question- can you use 2V heads with 4V exhaust manifolds?

Second question - can anyone tell me from this picture which exhaust manifold it has on it, 4V or 2V. Driver's side, best pic I could get without removing stuff.

   

.jpg   Driver\'sside2.jpg (Size: 72.39 KB / Downloads: 124)


Don from OMS was able to set me up with a "date correct" set of 4V closed chambered heads for my engine last year, they're out of the machine shop where I had some upgrades made and ready to be bolted on. Although the previous car owner gave me the 4V intake with the car, I'm going with a 4V Edelbrock Performer. I will soon be able to tell you guys first hand the difference between 2V and 4V heads on the same engine. I currently have the 2V Edelbrock Performer intake on the car so the only difference will be the heads.

   

Jim

It would help if I flipped the photo over.


.jpg   Flipped.jpg (Size: 87.97 KB / Downloads: 123)

Jim

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear
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#2
What's the beginning of the part number? It would appear yours have the same reinforcement ridge that these 4V's do:

http://www.ebay.com/itm/1971-1972-1973-F...9d&vxp=mtr

2V's:

http://www.ebay.com/itm/1970-71-72-73-Fo...63&vxp=mtr

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#3
Measure the exhaust ports on the heads and compare that to the sizes of the exhaust manifold openings. There's enough difference in 2V and 4V sizes that it will be obvious.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#4
Totalled;159885 Wrote:What's the beginning of the part number? It would appear yours have the same reinforcement ridge that these 4V's do:

http://www.ebay.com/itm/1971-1972-1973-F...9d&vxp=mtr

2V's:

http://www.ebay.com/itm/1970-71-72-73-Fo...63&vxp=mtr

That's best photo I could get, couldn't the whole number. The reinforcement ridge is why my friend thinks they're 4V.

Don C;159914 Wrote:Measure the exhaust ports on the heads and compare that to the sizes of the exhaust manifold openings. There's enough difference in 2V and 4V sizes that it will be obvious.

Agree, but I'm trying to get all the parts I need on hand prior to tearing it down so it doesn't sit for an extended period of time waiting on me to find the parts. If those aren't 4V exhaust manifolds I plan on picking up a pair prior to doing the tear down.

Jim

Jim

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear
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#5
Jim,

Hard to tell from pic but the part number looks like 9431-AB...

The correct 4V manifolds for 71-73 mustangs are...

LH D1ZE-9431-BA and RH D0AE-9430-G

Jeff
  Reply
#6
Quickest is to pull a manifold. It will be very apparent from the port in the manifold.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#7
A 4V manifold will have a notch in the corner of the port if you are looking at it off the car. The 2V does not.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#8
jeff8877;159926 Wrote:Jim,

Hard to tell from pic but the part number looks like 9431-AB...

The correct 4V manifolds for 71-73 mustangs are...

LH D1ZE-9431-BA and RH D0AE-9430-G

Jeff

Appears the prior owner left the old 4V exhaust manifolds on it when he switched the heads form 4V to 2V, surprised they don't leak.

Jim

Jim

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear
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#9
banana

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
  Reply
#10
jeff8877;159926 Wrote:Jim,

Hard to tell from pic but the part number looks like 9431-AB...

The correct 4V manifolds for 71-73 mustangs are...

LH D1ZE-9431-BA and RH D0AE-9430-G

Jeff

Jeff,

I should have read your post closer, you nailed it but I transposed the A&B and jumped to the conclusion I had 4V manifolds, I was wrong...but I've since purchased the correct set so I can continue to move forward, thanks!
Jim

.jpg   exhaust.jpg (Size: 91.43 KB / Downloads: 37)

Jim

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear
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