Intake Manifold Question

[Jim and Jutta]

I'm getting ready to put 4V quench heads back on my 71 M Code, I'm just getting all the part together. The prior owner for what ever reason put 2V heads on but I have the stock Intake manifold D0AE-9425-L and stock 4v Exhaust manifolds. It currently has an Edlebrock performer 2675 intake on it with the 2v heads which works with my ram-air system.

My question, (besides the weight advantage), is there enough performance advantage to justify spending $300.00 for a 4V Edelbrock performer intake (2665)over the stock DOAE-9425-L intake?

I know there are other options for intakes but the Edelbrock is one of the few that will be low enough to use with my ram-air system.

Jim

 

[TommyK]

Even the 4V performer is a bit of a slug on 4V heads. I can only imagine the 2V will be worse.

Will the car run and drive? Sure but I would venture to guess it would not perform as well as the 4V cast iron manifold you have.

 

[Jim and Jutta]

Even the 4V performer is a bit of a slug on 4V heads. I can only imagine the 2V will be worse.

Will the car run and drive? Sure but I would venture to guess it would not perform as well as the 4V cast iron manifold you have.

So you feel the original cast iron 4V intake will perform better than a 4V Edlebrock performer intake with the 4V heads?

 

[goodnigh]

We replaced the Edelbrock Performer LB that came with my 4V Cleveland with the

original iron manifold. One thing I noticed was the ports on the Edelbrock were smaller

than the iron one. All things aside, Bill Gay's group got it right with the Cleveland.

I can't imagine changing anything on the engine especially when related to air flow

can make it a better Cleveland.

mike

 

[TommyK]

Even the 4V performer is a bit of a slug on 4V heads. I can only imagine the 2V will be worse.

Will the car run and drive? Sure but I would venture to guess it would not perform as well as the 4V cast iron manifold you have.

So you feel the original cast iron 4V intake will perform better than a 4V Edlebrock performer intake with the 4V heads?

I think it will perform better than an Edelbrock 2V manifold on 4V heads. I thought that was the original question.

Below 3000 rpm the cast iron will slightly outperform the Eddy 4V manifold. Above that the Eddy 4V will be better.

 

[71mach351]

Absolutely no difference in performance between the Edelbrock and stock 4V manifold. Weight savings yes, but performance no. I wish I would have saved my stock intake instead of going to the edelbrock. Save your money.

 

[Jim and Jutta]

We replaced the Edelbrock Performer LB that came with my 4V Cleveland with the

original iron manifold. One thing I noticed was the ports on the Edelbrock were smaller

than the iron one. All things aside, Bill Gay's group got it right with the Cleveland.

I can't imagine changing anything on the engine especially when related to air flow

can make it a better Cleveland.

mike

Thanks Mike!

Even the 4V performer is a bit of a slug on 4V heads. I can only imagine the 2V will be worse.

Will the car run and drive? Sure but I would venture to guess it would not perform as well as the 4V cast iron manifold you have.

So you feel the original cast iron 4V intake will perform better than a 4V Edlebrock performer intake with the 4V heads?

I think it will perform better than an Edelbrock 2V manifold on 4V heads. I thought that was the original question.

Below 3000 rpm the cast iron will slightly outperform the Eddy 4V manifold. Above that the Eddy 4V will be better.

I guess I confused you talking about the 2V Edelbrock now on it, but was trying to compare the two 4V's. Thanks for the response, most of my driving will be below 3000 so it sounds like I can save the money and put the cast iron one on it.

Absolutely no difference in performance between the Edelbrock and stock 4V manifold. Weight savings yes, but performance no. I wish I would have saved my stock intake instead of going to the edelbrock. Save your money.

Glad I checked before buying the Edlebrock, thanks! Another example of why this site is so great.

Jim

 

[Totalled]

You can try out the edelbrock 4v that's on mine if you'd like. I'm not going to use it again.

 

[cudak888]

No reason to change an original M-code 4V intake for any reason other than weight, as stated above. It's a mild spreadbore for the 4300A and will accept a number of 600CFM carbs on top of it provided the bore isn't greater than 1-9/16" (the size of the primary bores; secondaries are a hair wider at 1-11/16"). A small spacer can also give you a few more options here.

On the other hand, Q-code 4V intakes from '72-73 have the unique spreadbore for the 4300D. Good excuse to swap for the Edelbrock - ability to mount most any carb that you wish.

-Kurt

 

[TommyK]

Yes I clearly fubar'd that one!

I will offer one other observation though where the edelbrock has an advantage over the M code intake.

The M code limits the butterfly size (600cfm 1-9/16") of the carb that can be used due to it's four hole carb pad unless a spacer is used. The Edelbrock has a split plenum design which will accept any square bore carb.

 

[trainey]

I have an original 4V iron intake from a 71 if anyone is interested...make an offer

 

[mustang7173]

Jim and Jutta,

I would say that the previous owner installed the 2V heads to get better low-end, off the line power. This is where 95% of the driving and RPM range will be. The big 4V heads were short lived for a reason, just as the BOSS 302 was short lived. The 351C-4V heads had ports and vales big enough to just about put tennis balls into. Even Ford knew the cylinder heads had valves that were too big!

Ford engines with the smaller valves, smaller runners and good velocity will make more torque, which is what moves the automobile from 0 -60. How many times will you one push the engine above 5,000 RPM, and how often will you be below that? There are numerous builds of 351W's with small runner cylinder heads that will kick the crap out BOSS 302, and 351C4v's on a daily basis.

At least you have the quenched area in the cylinder heads. Hopefully, they have the smaller valves that will help in the air velocity.

By the way, I am running a 351 C with 4 Bolt mains, 1971 2 V cylinders with high flow valves, three angle valve job, Edelbrock performer plus camshaft and 351C 2V Edelbrock Performer intake w/ Holley 750 4V. Runs really strong off the line and up through the 6000 RPM range. I would run it against most 351C-4V engines.

Mustang7173

 

[cudak888]

The M code limits the butterfly size (600cfm 1-9/16") of the carb that can be used due to it's four hole carb pad unless a spacer is used. The Edelbrock has a split plenum design which will accept any square bore carb.

True - though someone interested in pulling the Ford intake could probably take a die grinder to the 1-9/16" ports and open them up (big question is the skill of the grease monkey making the holes), as there's more than enough steel to work with on it.

-Kurt

 

[Jim and Jutta]

You can try out the edelbrock 4v that's on mine if you'd like. I'm not going to use it again.

Thanks Pat, may take you up on that if I run into issues with the original cast iron intake, I'm going to try to make it work first.

Jim

Yes I clearly fubar'd that one!

I will offer one other observation though where the edelbrock has an advantage over the M code intake.

The M code limits the butterfly size (600cfm 1-9/16") of the carb that can be used due to it's four hole carb pad unless a spacer is used. The Edelbrock has a split plenum design which will accept any square bore carb.

I was hoping to use my current Edelbrock Thunder Series, 650CFM carb on the cast iron intake. The manual says venturi diameters of 1-3/16" for the primary's and 1-5/8" for the secondary's. Throttle blade diameters are 1-7/16" for the primary's and of 1-3/4" diameter for the secondary's.

Pic of the intake:

Jim and Jutta,

I would say that the previous owner installed the 2V heads to get better low-end, off the line power. This is where 95% of the driving and RPM range will be. The big 4V heads were short lived for a reason, just as the BOSS 302 was short lived. The 351C-4V heads had ports and vales big enough to just about put tennis balls into. Even Ford knew the cylinder heads had valves that were too big!

Ford engines with the smaller valves, smaller runners and good velocity will make more torque, which is what moves the automobile from 0 -60. How many times will you one push the engine above 5,000 RPM, and how often will you be below that? There are numerous builds of 351W's with small runner cylinder heads that will kick the crap out BOSS 302, and 351C4v's on a daily basis.

At least you have the quenched area in the cylinder heads. Hopefully, they have the smaller valves that will help in the air velocity.

By the way, I am running a 351 C with 4 Bolt mains, 1971 2 V cylinders with high flow valves, three angle valve job, Edelbrock performer plus camshaft and 351C 2V Edelbrock Performer intake w/ Holley 750 4V. Runs really strong off the line and up through the 6000 RPM range. I would run it against most 351C-4V engines.

Mustang7173

Yes, lots of discussions of why someone would swap out 4V heads for 2V heads, low end torque seems to be the primary reason but I also heard that the 4V closed chambered heads required higher octane fuel and fuel prices jumped in the 70's making that another factor for switching to 2V heads. Once I swap out the 2V heads and put the 4V closed chambered heads on I'll be answer those two questions.

Jim

The M code limits the butterfly size (600cfm 1-9/16") of the carb that can be used due to it's four hole carb pad unless a spacer is used. The Edelbrock has a split plenum design which will accept any square bore carb.

True - though someone interested in pulling the Ford intake could probably take a die grinder to the 1-9/16" ports and open them up (big question is the skill of the grease monkey making the holes), as there's more than enough steel to work with on it.

-Kurt

Kurt, I'm not sure I could use a spacer since I have a ram air system, I don't think there is enough clearance.

Jim

 

[mustang7173]

Jim,

Check out this option for the 351C-4V heads-

http://www.mpgheads.com/port_plates_a.php

mustang7173

 

[hyena429]

Jim just tring to stay away from the 4v vs 2v argument.."jk" .that has been battled on here more threads than anything.

Btw Jim...I had to switch to the Edelbrock only cause a new 750 would not bolt up too my old cast iron...bad luck of owning a 73 cobrajet manifold...and the EGR Plate with the grove made it a puddy fill nightmare if i was too try and keep it..lol..You mite have a issue getting any carb to fit up normal too even your square bore...With out a extra plate..But then if you have ram air it hurts that too.

Even ran into it while tring to bolt a Edelbrock carb to my freinds chevy truck with old cast iron on it...We had to use a spacer to make it work with the factory manifold.

 

[Jim and Jutta]

Jim just tring to stay away from the 4v vs 2v argument.."jk" .that has been battled on here more threads than anything.

Btw Jim...I had to switch to the Edelbrock only cause a new 750 would not bolt up too my old cast iron...bad luck of owning a 73 cobrajet manifold...and the EGR Plate with the grove made it a puddy fill nightmare if i was too try and keep it..lol..You mite have a issue getting any carb to fit up normal too even your square bore...With out a extra plate..But then if you have ram air it hurts that too.

Even ran into it while tring to bolt a Edelbrock carb to my freinds chevy truck with old cast iron on it...We had to use a spacer to make it work with the factory manifold.

Yeah the 2V verses 4V has been beaten to death on this and other boards, lots of pros and cons. I still have the rebuilt 4300 carb but I replaced that with Edelbrock 650 carb because the 4300 was so high maintenance and I found the Edelbrock Carb did indeed make the car start and run better so I want to stick with it.

 

[mach71351c]

I don't think you will feel any loss of torque switching to 4V heads. I was ounce a preacher of the 2v.:dodgy: It's funny that some make it sound like 2.3 pinto will beat a 4V off the line.

Jim,I can't wait to here what you think of it when done.

 

[trainey]

I am also moving to 4v closed chamber, Edelbrock performer, combo on a rebuilt .40 over block. Once I get all of my stuff together for the AOD swap I'll be ready to install.