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Need a Carb recommendation


73' mach 1
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My factory carb could use a rebuild but from what I hear it's better to just upgrade from the 4300d. I've also hear that you can't just drop any old carb on top of the factory intake due to the spread bore. As i've mentioned in my intro...the carb world to me is completely new so please forgive my ignorance when asking some questions that might seem simple.

I've heard good things about holley carbs and I'd like to keep my factory intake if possible. I plan on keeping the car close to stock with the exception of long tube headers and exhaust. If the motor ever went then I'd put a mild cam in it. So if it's possible to have a carb that would be ok for stock but would also allow me to grow into it if I had to that would be better. I intend to use the car as a weekend cruiser with some spirited street driving. No track or autocross. The motor is a 351C 4v with a 4 speed top loader. Currently the gears are 3:89 but I might chicken out and put 3:50 3:55's unless you guys think I should stick with the 3:89's? Thanks

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Part# 0-80459SA holley spread bore 750cfm carb.would be a good fit for stock or mild build.Keep the 3:89's if you want to add a mild cam look at the Comp Cams Dual Energy cam 275DEH 2000 - 6000 RPM range.

2zdx09d.png

Yea,Tho i cruise through the valley of the shadow of rice,I will fear no Turbo,For Torque art with me.Thy rods and crankshaft,they comfort me. :D Robert [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=357]Visit My Garage[/button]

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Part# 0-80459SA holley spread bore 750cfm carb.would be a good fit for stock or mild build.Keep the 3:89's if you want to add a mild cam look at the Comp Cams Dual Energy cam 275DEH 2000 - 6000 RPM range.

 

Isn't that Holley a square bore? I had once tried a square to spread bore adapter to keep my original intake and really didn't like the performance. I would just go with a performer manifold now.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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I'm sure holley makes a good matching intake for the carb that would be suggested correct? Would those part number be? Do I have to worry about any clearance issues? Just wondering what everyone else has used with success?

www.puregemdetailing.com

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An Edelbrock Performer intake and a Quick Fuel ss-680-vs carb will work with your current combo and the carb will not be a limiting factor for future upgrades.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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That Holley won't bolt to the 73 spreadbore intake. A good option to keep it mostly stock would be a 70-71 M-code iron intake with a carb of your choice. You may need to run a small spacer for the butterflies to clear the bores on the mounting pad.

 

 

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From what you indicate as using the car for a cruiser and spirited occasional driver, there isn't any major advantage in keeping the 4300D spread-bore manifold on the engine insofar as performance. Changing to an Edelbrock performer manifold (or similar) will open up the choice of carbs that can be easily bolted on. The change will probably be a major wake-up in terms of ease of starting, off-the-line performance, and improved gas mileage. Keep the stock 4300D manifold and carb on the shelf to either sell outright or include with the car if you ever get an offer that can't be passed up.

 

On the other hand, if you have the carb professionally rebuilt by someone who knows what they're doing (may take some research to find someone, and this forum can assist with recommendations) you can run the 4300D for a long time with decent performance. The cost of a 4300D rebuild will be about the same as changing the manifold and carb to standard square-bore configuration. You will have to learn a few things about carbs as it is (how to set cold start choke, warm idle fuel/air mix, etc) but it's not all that difficult to learn the basics. If an engine rebuild comes due, then would be the time to discuss changing the intake/carb set up with the engine builder to meet the goals of the rebuild. With that in mind, the condition of your current 4300D should have bearing on any decision. One issue the 4300D is prone to is a cracked base plate. If that occurs, or something like internal passage erosion is evident, then changing to an aftermarket setup is the way to go.

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I don't mind doing the aftermarket intake with a new carb I just need to know what combo works the best for my intended use. Which would be spirited weekend cruiser. Plus it would be nice to allow for a mild cam upgrade down the road. What CFM would you say 650 at the very least? Is it cool to do an eddy intake with Holley carb or just do Eddy/ Eddy? I just don't know whats good these days? I've been out of the performance market for about 10 years and this is my first carb car.

www.puregemdetailing.com

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There's another thread about carb/intake decision going on, and here's my input to that (post 13): http://www.7173mustangs.com/thread-decision-time-advice?page=2

 

600 cfm is really about all you'd want without warming up the rest with a performance valve-train (cam, rockers, head work, etc.) and higher-flowing exhaust (headers, etc.).

 

It all works together... simply adding a bigger carb and performance intake will only give you slightly better performance - it's only a small part of the equation for more power. You can only feed the beast so much more before it starts to choke on too much. ;)

Eric

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There's another thread about carb/intake decision going on, and here's my input to that (post 13): http://www.7173mustangs.com/thread-decision-time-advice?page=2

 

600 cfm is really about all you'd want without warming up the rest with a performance valve-train (cam, rockers, head work, etc.) and higher-flowing exhaust (headers, etc.).

 

It all works together... simply adding a bigger carb and performance intake will only give you slightly better performance - it's only a small part of the equation for more power. You can only feed the beast so much more before it starts to choke on too much. ;)

 

Thanks for the link. I will at the very least do a full exhaust along with the new carb setup. Since rockers and springs are kind of easy to do would there be a suggestion to do that also? What are the factory rocker size?

www.puregemdetailing.com

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When you do the exhaust I highly recommend swapping out the manifolds with headers. Made a huge difference on mine even with just a factory 2v set up.

73 Grande H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

 

- Jason

 

 

082-hot-rod-power-tour-2017-1970-1970s.jpg

 

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Wow. Cool I am curious how they fit and perform. I went with a set of Headmans uncoated and had my local coating place do cerakote on the outside and a layer of insulkote on the inside. Ended up costing about the same (maybe a few bucks less) than buying them already coated but I know the local guys here and they do a fantastic job. Fitting the drivers side header in was a PITA. Just an FYI if you are doing them yourself. My winter project is to upgrade the ignition and intake side since it is still a 2V. Going with a Holley 300-12 intake I bought from a member here and cleaned up and had it coated as well. Looks great in blue. I am going with the new Street Demon 750 CFM with the composite bowl. I've heard really good things about the primary/secondary design on these in regards to throttle response. Also putting in a Pertronix III.

73 Grande H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

 

- Jason

 

 

082-hot-rod-power-tour-2017-1970-1970s.jpg

 

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That Holley won't bolt to the 73 spreadbore intake. A good option to keep it mostly stock would be a 70-71 M-code iron intake with a carb of your choice. You may need to run a small spacer for the butterflies to clear the bores on the mounting pad.

 

sorry about that , thought i gave part number for Holley spread bore carb .

2zdx09d.png

Yea,Tho i cruise through the valley of the shadow of rice,I will fear no Turbo,For Torque art with me.Thy rods and crankshaft,they comfort me. :D Robert [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=357]Visit My Garage[/button]

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If your still running a 4300D then your going to want to change the intake as well. It's been a while but I believe the 4300D uses a Spread Bore pattern and if you go to a Holly the pattern is different. I bought a used intake from a 1970 351 Cleveland that has a Holly pattern and I bought a Holly 715cfm with central pivot floats (Shelby) carb. The 2 seem to work very well on my Q code but parts for that carb are getting harder and more expensive to find.

Going fast is fun but life is short so slow down and enjoy the ride :D Frank

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There's another thread about carb/intake decision going on, and here's my input to that (post 13): http://www.7173mustangs.com/thread-decision-time-advice?page=2

 

600 cfm is really about all you'd want without warming up the rest with a performance valve-train (cam, rockers, head work, etc.) and higher-flowing exhaust (headers, etc.).

 

It all works together... simply adding a bigger carb and performance intake will only give you slightly better performance - it's only a small part of the equation for more power. You can only feed the beast so much more before it starts to choke on too much. ;)

 

+1

If you improve the intake flow without doing the exhaust too you will see some improvement. Doing both is ideal. An important thing to remember is that you need to select all the parts that will work together. For example, getting a cam that in its power band at 2500 to 6000 rpm with a rear axle of 2.75 : 1 would not work very well and you will need to be at high freeway speeds for the cam to be in its power band. This is another subject but is important one to consider when getting parts. Best to decide what your overall goal is and then go from there. Will save you $$$ in the end.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Given the stated use, 4V heads, 3.89:1 gear, and manual transmission I feel you could use either a vacuum secondary or mechanical secondary carb. I'd consider the Quick Fuel HR series in 750/780 cfm as they have great adjustability for the price, they perform well, and the adjustability and size will work with what you have now as well as you planned upgrades.

 

I'd consider the Edelbrock Air Gap dual plane intake for the same reasons.

 

The rocker ratio is 1.73:1. If the valve train is working fine now the benefits of changing to roller rockers would be minimal. The same goes for the springs. The time to consider those changes is when/if you decide to do a cam change and increase the RPM limit. If the heads are 73 4V open chamber heads, you have about 8.0:1 compression ratio that doesn't leave a lot of room for performance cams with significant overlap in my opinion but, everyone's opinion of what a performance cam is varies.

 

The Hooker comps, not super comps, fit well and work well. Good luck with the improvements.

 

Chuck

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Good info here guys. I'm very good with leaving the heads alone for now. I'll only get into the motor if something goes wrong. From there I could get into changing the heads if need be to support the rest of my setup, up to and including getting everything ported. I've see a lot about changing the timing chain gears as a must/standard. If I'm taking the front apart to do that is there anything else I should do while that's apart? Water pump? Flex fan? Any of this stuff worth doing if nothing is wrong and are there good aftermarket parts that are better than factory?


When you do the exhaust I highly recommend swapping out the manifolds with headers. Made a huge difference on mine even with just a factory 2v set up.

 

Wow. Cool I am curious how they fit and perform. I went with a set of Headmans uncoated and had my local coating place do cerakote on the outside and a layer of insulkote on the inside. Ended up costing about the same (maybe a few bucks less) than buying them already coated but I know the local guys here and they do a fantastic job. Fitting the drivers side header in was a PITA. Just an FYI if you are doing them yourself. My winter project is to upgrade the ignition and intake side since it is still a 2V. Going with a Holley 300-12 intake I bought from a member here and cleaned up and had it coated as well. Looks great in blue. I am going with the new Street Demon 750 CFM with the composite bowl. I've heard really good things about the primary/secondary design on these in regards to throttle response. Also putting in a Pertronix III.

 

I'll definitely report back once I get them installed. It will be sometime before the spring. I'll match that up with a set of either spintech pro streets or sportsmans. I'm leaning toward sportsman.

www.puregemdetailing.com

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If the engine has the OEM timing set, low and mid ranges will be improved my installing a timing set that does not have the retarded crank sprocket.

 

Chuck

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If the engine has the OEM timing set, low and mid ranges will be improved my installing a timing set that does not have the retarded crank sprocket.

 

Chuck

 

Ok...I'm confused on this now? You can't just advance the required timing with a screw driver and timing gun? I need to change the sprocket first to get the timing advance I want back over the factory 4 degree retarded? I'm still trying to pick this up.

www.puregemdetailing.com

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I think he meant that the crank sprocket is 'retarded' because it's made of nylon (which would actually be the camshaft sprocket, I believe) - or maybe not. Chuck's forgotten more of this stuff than I'll ever know. :chin:

 

To answer your second questions: Yes, you can change the timing by using a 1/2" wrench to loosen the dizzy clamp and rotate the distributor itself while using a timing light.

Eric

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If the engine has the OEM timing set, low and mid ranges will be improved my installing a timing set that does not have the retarded crank sprocket.

 

Chuck

 

Ok...I'm confused on this now? You can't just advance the required timing with a screw driver and timing gun? I need to change the sprocket first to get the timing advance I want back over the factory 4 degree retarded? I'm still trying to pick this up.

 

What Chuck is referencing is the cam timing, not the ignition timing. The timing set consists of the cam sprocket, crank sprocket and timing chain and connects the camshaft to the crankshaft. The camshaft controls when the vales open, how long they stay open and when they close. Those events must be "timed" to the position of the piston(s) in the cylinder(s) for all the combustion events to occur with the split second precision needed for an engine to run properly. In order to meet emissions requirements Ford "retarded" the camshaft timing which unfortunately negatively impacts engine performance in the low and mid rpm operating ranges. This was done by using an offset keyway on the crank sprocket. Installing a "straight up" timing set will advance the factory camshaft timing events and provide a modest increase in low and mid rpm performance.

 

Ignition timing controls the point at which the spark plug fires relative to piston position in the cylinder and is another matter entirely. However it is also an important part of improving the performance of your engine and should not be overlooked.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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In an attempt to meet emissions standards Ford retarded the cam in relationship to the crank by moving the position of the keyway slot in the crank gear of the timing set. It did lower emissions but it also made the engine more lazy in the lower rpm ranges. A lot of things they did lowered emission but greatly reduced power and gas mileage. Go figure.

 

Chuck

 

EDIT: I didn't see TommyK's post before I responded. I didn't mean to be redundant.

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Wow! Thanks guys for schooling me proper. With regards to emissions...I remember on my caprice I was able to remove my EGR valve and block that off with a plate. I was also able to remove the air pump and all the hoses with it and then just disable them in the PCM. Can the same be done here? Could I just plug up those vacuum lines or do they truly need to be active to keep some kind of vacuum balance? Here is a pic of my carb. I noticed that there is no vacuum line connected to my EGR and I noticed nothing connected to the fitting on the back of the carb. What is the fitting at the top of the carb go to and is it necessary? I found a hose that has a screw in it blocking it off on one end and I think the other end is going to whats called the temp sensor located on the front of the block. Any info you guys can provide that would allow me to "uncork" all the power ford pulled out due to emissions would be awesome. I understand a lot of the power held back is in the heads and compression but anything else I could get rid of would be great. I'll definitely get the correct timing sprocket. Not trying to be lazy but I just want to make sure I get the correct stuff here...can someone please provide me a part number for the right sprocket and stuff? Like I said, this is my first classic and I'm starting to get excited to get my hands dirty again. I greatly appreciate all the info here guys.

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www.puregemdetailing.com

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