Responsive Carb Ideas

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Carguy4sp

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Guys I have a near stock 351 Q code 1972 mustang with a 4 sp. I took it for a 2 hour ride last Sunday and all systems worked well except carb. I have a 3:50 traction lock and my car is sluggish off the line and my secondary butterfly's are not opening. So my 4v is running on two barrels.

I really like mechanical secondaries but the pro carb builders say vacuum is best.

I was thinking of the 600 series of the HP Holley line.

The car will be just a street car but I would like a quick snap when I lay the right foot all the way down. I guess a crisp snap would be a good way to describe what I am looking for.

I want an upgrade from my stock carb, what would you recommend any why ?

Thanks Rodney from SW Florida

 

TommyK

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What intake manifold do you have?

 
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I just put a Blue Thunder intake manifold & a Holley 770 Street Avenger Carb on my 72 Q code. Really woke it up! After some tuning & timing changes it runs way better than w/the 4300D carb. My car has a c6 trans w/a 3.25 rear gear & now it will spin the tires no problem from a dead stop. Before it would hardly break loose.

You could probably go with a little smaller carb, but I think 600 is too small. The stock 4300 is a 715 cfm carb and my engine is rebuilt a little bit over stock, so that's why I choose the 770. There are a lot of choices out there, so good luck on whatever you decide to go with.

 

TommyK

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You will need to run Holley square bore to Motorcraft spread bore adapter.

For a budget carb the Summit carbs are hard to beat.

If you want something with a little more bling and tune-ability then a Quick Fuel 680VS would be my choice.

 

Carguy4sp

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You will need to run Holley square bore to Motorcraft spread bore adapter.

For a budget carb the Summit carbs are hard to beat.

If you want something with a little more bling and tune-ability then a Quick Fuel 680VS would be my choice.
no bling required just a good punch when you need it.

 

c9zx

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As Tommy K said the summit VS carb is a good value as is the QF HR series carbs. Another good value is the QF Slayer, lots of tenability for not a lot of money. The Holley HP series comes calibrated for street/strip to racing configurations and would require significant recalibration to work well in your application. Trans-Dapt makes an adapter for the manifold. I too am a fan of double pumpers for many applications. The four speed helps the case for a DP but the 3.25 gear does not. I too would suggest a VS carb for your application. No matter what you buy, expect to do some calibration to arrive at optimal functioning. Just my thoughts. Chuck

 

Carguy4sp

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As Tommy K said the summit VS carb is a good value as is the QF HR series carbs. Another good value is the QF Slayer, lots of tenability for not a lot of money. The Holley HP series comes calibrated for street/strip to racing configurations and would require significant recalibration to work well in your application. Trans-Dapt makes an adapter for the manifold. I too am a fan of double pumpers for many applications. The four speed helps the case for a DP but the 3.25 gear does not. I too would suggest a VS carb for your application. No matter what you buy, expect to do some calibration to arrive at optimal functioning. Just my thoughts. Chuck
Thanks

I have 3:50 gears

I am also thinking of the spread bore Holley.

 

barnett468

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you need to set yor timing curve so it is optimal for your engine.

what carb do you have?

how do you know the secondaries are not opening?

why dont you fix the carb you have?

a vacuum secondary carb is not "best" for a manual trans car.

.

 

Carguy4sp

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you need to set yor timing curve so it is optimal for your engine.what is the proper timing?

what carb do you have?4300d

how do you know the secondaries are not opening?can,t tell but sluggish and slow to build rpm.

why dont you fix the carb you have? I want a performance upgrade.

a vacuum secondary carb is not "best" for a manual trans car. Thanks

.
 

spothead

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I'm happy with my Barry grant speed demon 750 vs carb. 351 4v c6 3.55's

 

Carguy4sp

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I'm happy with my Barry grant speed demon 750 vs carb. 351 4v c6 3.55's
Any mods on your car .

Any signs of over carburation?

What color is your tail pip tips ?

What is your timing set on ?

Can you tell when the secondaries open ?

Is it a spread ore 4165 ?

Thanks

Rodney from S W Florida

 

spothead

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Spread bore

Yeah you know when the secondaries open

Timing can't remember.....msd 6al pro billet distributor.

Tail pipe tips have some black soot.

Definitely be not over carbureted

Mods.....tons of them. Edelbrock intake,msd ignition,big cam, headers.

 

rpxr400

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I just put an Edelbrock 1405 on my '72 Qcode since my carb was causing problems. Mine is an auto, but once I got he kickdown lever adjusted, when I stomp on it, between the downshift and the 4V opening, I'm very pleased.

 

vozaday

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My understanding is manual is best to be mated with mechanical secondaries. I like the ease of adjustment of Holley carbs. I'm a newb to carbs but through trial and error I got it dialed in to where it just gets up and goes. No hesitation what so ever.

 

vozaday

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That being said, why not look into fuel injection? FiTech has a 400hp system for $795, you still need the fuel pump after that but for just over $1100 it may be a worth while purchase.

 
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