Plans for the car

[Valhallo]

Hey guys. I was hoping somebody might have some input on my plans for the car, now that I'm starting to make some money I can put into the mustang.

My original plans were to put a 4v carb on my 2v 351C, but I'm starting to reconsider. Is it worth the investment to put some 4V heads on my 2V block and working from there, or should I continue with my original plans? I was going to use a 750cfm 4 barrel vacuum secondaries holley carb on an Edelbrock 2750 intake.

Any thoughts?

 

[trainey]

It depends on what you are building it for. I have the same setup, and have decided to stay with the 2V heads, adding a Cam kit, edelbrock airgap intake, and 600cfm holley. I am also going from the stock 2.75 conventional rear to a 3.50 traction lok. After consulting with the gearheads here, and by running the numbers on some performance software, the improvement is about right for me, which is street use.

 

[Tnfastbk]

The blocks are the same, the changes start from the heads up

 

[c9zx]

As others have said, it depends on what you want the outcome to be. How do you want to use the car? As Roy said, the power is about the heads. Chuck

 

[will e]

The blocks are the same, the changes start from the heads up

There are some differences in the block and crank but they won't affect peformance (just ability to handle RPM)

Not trying to be picky.

Yeah, the real question is what you want to do and how much money you want to spend? If your current heads are in good shape then you won't be out much if you get a 4bbl manifold for those 2v heads. (If you ever decide to go with 4v heads you can sell the manifold pretty easy).

With the bigger port heads you need to swap out exhaust manifolds too. The 4v can be a little pricey. Headers are an option (preferred imho).

What the bigger heads will get you is more flow. This will matter the most at higher RPM. If you have a stockish cam then you won't be getting into the RPM range where you will benefit from the larger heads.

It's really a combination kind of thing.

So, back to your question. If you are looking for a little more 'get up and go' for not much green then toss on an aftermarket manifold and a good 4bbl. I would actually go less CFM then 750. Keep the secondaries vacuum controlled (double pumpers look cool but for the street the vacuum is an easier tune).

 

[72fastback]

As stated before you will get more high end torque with the 4v heads but. The 4v heads were intended for oval track racing {correct me if I'm wrong}. The 2v heads will give you more low end torque. Which means a better acceleration from a stand still. You can make great power with the 2v heads with a cam change and an aftermarket intake. From what I have read and experienced with my car. I have 4v closed chamber heads. The engine seems to wake up at around 3000 to 4000 rpm. If you have a C6 a higher torque converter might be something you will want to get.

 

[Tnfastbk]

The blocks are the same, the changes start from the heads up

There are some differences in the block and crank but they won't affect peformance (just ability to handle RPM)

Not trying to be picky.

Such as? There is no 4 bolt 2v that I know of but the majority of 4v blocks are 2 bolt mains. Just curious to what Im missing, I learn something new on here daily

 

[Valhallo]

Thanks for all of the info guys. I just want some more street power so I think I will stick with the 2V heads.

The blocks are the same, the changes start from the heads up

There are some differences in the block and crank but they won't affect peformance (just ability to handle RPM)

Not trying to be picky.

Yeah, the real question is what you want to do and how much money you want to spend? If your current heads are in good shape then you won't be out much if you get a 4bbl manifold for those 2v heads. (If you ever decide to go with 4v heads you can sell the manifold pretty easy).

With the bigger port heads you need to swap out exhaust manifolds too. The 4v can be a little pricey. Headers are an option (preferred imho).

What the bigger heads will get you is more flow. This will matter the most at higher RPM. If you have a stockish cam then you won't be getting into the RPM range where you will benefit from the larger heads.

It's really a combination kind of thing.

So, back to your question. If you are looking for a little more 'get up and go' for not much green then toss on an aftermarket manifold and a good 4bbl. I would actually go less CFM then 750. Keep the secondaries vacuum controlled (double pumpers look cool but for the street the vacuum is an easier tune).

So if a 750 CFM is too much, what would you guys suggest? a 600?

 

[sm3570]

I would think 600 would suffice if you are sticking pretty close to stock. My big block has a 600 and there have been 0 issues with it (the stock carb was a 600, I upgraded to a Holley).

 

[cobra3073]

Zac, I agree with Trainey where he speaks of changing the rear gear ratio on his Mustang.

Based on your stated desires, it sounds as if you are looking for a bit more street performance. I wish I knew 35 years ago what I know now when it comes to setting up a car for more "go."

Most automobiles from the 70s (to include those equipped with the 351C 2V) came with rear gear ratios below 3.00:1 which are usually excellent for highway cruising but not the best when you want "snappy" performance or acceleration when driving around town. The ABSOLUTE first change you should make for increased performance in this area is the change to a higher (numerically) rear gear. For most people, driving our cars, that will be something like a 3.50:1. You will be absolutely AMAZED at the difference that will make. Keep in mind that this will result in more fuel usage. The 351C 2V heads are perfectly fine for normal "fun" driving. I have seen similarly equipped 351C 2V "beat" 351C 4V during my "street racing" days.

After you are satisfied with the gear change, I would then look at freeing up the exhaust system, maybe with dual tail pipes if you do not already have them. I would not go with headers until after I had made a decision on what I REALLY want from the car. Dependent upon how far you go with other changes, you may have to change the size of your header tubes.

If I decided competitive races were in my future for the car, I would then start looking at making the "air pump" (engine) more efficient through Intake/carb, camshaft, cylinder head, etc. changes. At this point, every time you change something, it will usually entail going back to the "drawing board" and changing something else "in the system." I say system because that is what you have and from the Factory, everything is designed to work as a system.

I hope this helps and not confuse the issue.

BT

 

[will e]

The blocks are the same, the changes start from the heads up

There are some differences in the block and crank but they won't affect peformance (just ability to handle RPM)

Not trying to be picky.

Such as? There is no 4 bolt 2v that I know of but the majority of 4v blocks are 2 bolt mains. Just curious to what Im missing, I learn something new on here daily

Well, I believed that all factory 4v clevelands had the 4 bolt main caps and nodular cranks but after doing a little research I am incorrect in that belief. Turns out only the Q/M codes did. I am a little surprised by this since I have a 4 bolt main block engine (It didn't come with the car). I also have closed chambered heads with non-adjustable rockers (which were not on the block when I got it). I wonder what the heads came off of???

For a while I was running 2v heads on my 4 bolt main block.

Anyways, I stand corrected. In some cases the 2v and 4v block are the same. Thanks for helping me learn!

 

[Tnfastbk]

The blocks are the same, the changes start from the heads up

There are some differences in the block and crank but they won't affect peformance (just ability to handle RPM)

Not trying to be picky.

Such as? There is no 4 bolt 2v that I know of but the majority of 4v blocks are 2 bolt mains. Just curious to what Im missing, I learn something new on here daily

Well, I believed that all factory 4v clevelands had the 4 bolt main caps and nodular cranks but after doing a little research I am incorrect in that belief. Turns out only the Q/M codes did. I am a little surprised by this since I have a 4 bolt main block engine (It didn't come with the car). I also have closed chambered heads with non-adjustable rockers (which were not on the block when I got it). I wonder what the heads came off of???

For a while I was running 2v heads on my 4 bolt main block.

Anyways, I stand corrected. In some cases the 2v and 4v block are the same. Thanks for helping me learn!

Thats why I said I learn something new here everyday, was not pulling your leg. Thats why this site rocks.

 

[mach71351c]

I replaced my 3.00s with a (N) case 3.50s. What a difference in acceleration. My engine was bone stock 351C 2V. It maid the car way more fun to drive.

 

[Totalled]

Thanks for all of the info guys. I just want some more street power so I think I will stick with the 2V heads.

I would find what gear ratio you have now. 3.50 gears, or even 3.25s for easy highway cruising, edelbrock performer, 600 CFM carb, dual exhaust with an h-pipe, upgraded ignition. Bolt on's without having to really open up the motor will wake it up and make it a completely different car than what you have now. And, if you want more later, you can always add to it.

 

[Don65Stang]

I would find what gear ratio you have now. 3.50 gears, or even 3.25s for easy highway cruising, edelbrock performer, 600 CFM carb, dual exhaust with an h-pipe, upgraded ignition. Bolt on's without having to really open up the motor will wake it up and make it a completely different car than what you have now. And, if you want more later, you can always add to it.

Exactly as stated above and all the other posts on this thread. 600cfm is perfect for a street build.

 

[Valhallo]

Thanks for all the help guys. Sounds like the first thing i'm going to do is change out my gear ratio. As soon as I get it home that is.. I was driving it to the store the other day and one of my vacuum lines busted off, and now it wont start. It's one of the lines that goes into my water pump, so now i'm going to NAPA to see if they have the part I need. If not, I get to tow the car back to my house, order the part and wait for it to get here.