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I have a 1966 ford mustang with a mild 289 and a ford speed.
I have 3:25 rear gears.
I would like to replace the carb with a Barry Grant speed demon 575 with a mechanical secondaries.
would this work or do I need to use vacuum secondaries?
 

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What exactly do you mean when you say mild? I think the Barry grants are still base off a 750 cfm holley. they take them and open them up to flow more cfm. Mine was 850 cfm from a 750 model. That said, if your engine is basically stock, that is going to be too much carb. Especially in double pumper form. Mechanical secondaries pump fuel weather or not the engine needs it, as apposed to vacuum secondaries that actuate and draw only as much fuel as the engine demands. Barry Grants are really for race ready engines. You probably don't want to hear this but, if your 289 is nearly stock, you should be looking at something like an edelbrock 600 afb vacuum secondaries. It is cheap. It will never leak because the body is all one peice (not seperate fuel bowls) and you don't have to tune it because they come pretuned and you really don't have to mess around with it. (I had one of those too) Honestly; A barry Grant carb is how you top off a race motor not start the race motor build.
 

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I ran a spread bore 450 Holley on a stock block 302 and had happy results with it. Vacuum secondaries would be better for you with what you have now.
Dave
 

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It depends on what you mean by mild but I would not go any bigger than a 600cfm regardless of brand. A 289/302 just doesn't need anything bigger unless it is a long way on the strip only side (and I mean WAY hopped up). It just can't use the amount of fuel flowed by anything bigger. Past 600 cfm you will have nothing but problems in my experience. You certainly don't need anything that is a double pumper. More gas only means more power if you can flow the air to use it and the exhaust to get rid of it after it's done it's work.
 

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I have a 65 with a mild 289 and auto trans. I'm running a Holley 570 Street Avenger as suggested by the engine shop. You can change the springs on it for power vs. economy. The engine is still rather new and I haven't really opened it up yet (less than 100 miles). My understanding is to stay under 600cfm for less than 300hp on the 289 (per Holley web site).

Holley Performance Products 570 CFM Four Barrel Carburetor*0-80570


How do you like the 3:25 rear? I'm thinking of adding a limited slip 3:25. I think I have 2:80 to 1.
 

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I have a pretty much stock 302 roller in my car and I use the Edelbrock #1406 - 600cfm. It works great! No powervalve to blow out like the holley.
 

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I've got a 68 mustang with a 289 and i am thinking about putting an edelbrock carburetor on it but in not sure which one to use, can anyone tell me what the difference is between the 1405 and the 1406? And maybe which one they would recommend that i should use! I would appreciate it!
 

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I was having trouble choosing a carb for my 351c.I decided on the holley 670 street avenger duel feed, ele choke ,vac sec.OOOhhh man i love it.I did have a holley 600 on it.For your 289 the holley 570 may be a good choice.Mine came with a 2hr video on how to tune,trouble shoot,ect..Check it out.
 

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actually barry grant makes a great carbureter and will set it up for your engine. when I bought mine I called barry grant directly they asked for all my engine specs including the altitude where I live and sent the carb out I bolted it on and it was perfect. and btw it is not a rebuilt holley. they look similar but are a completely new casting with smoother bores and numerous other differences. the real question here is why do you want mechanical secondaries and the barry grant carb in the first place. are you looking for more horsepower? are you looking for a better looking carb?

why exactly are you looking for a new carb because for a mild 289 you will be hard pressed to beat the original autolite carb that was on it from the factory.
 

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hi garrardao,

The differenc between the 1405 and the 1406 is the 1406 is electric choke and the '05 is manual choke.

I have the 05 and it is all good.

Steve
 

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I have a slightly modified 289 in my 67 and I tried a vacuum 600 holley and a electric 650 edelbrock double pump. I got lucky in the fact that the guys who have been helping me plan out my mods at the speed shop and parts store had spare carbs they let me try running on the car before I bought.
Really liked the performance on the 650 more so than the 600. I've been told a few times that I'm waisting extra gas, but I'm still happier with it.

Mods are edelbrock performer intake, comp cams camshaft (can't remember the specs right now) - kept it street size though, new lifters and double valve springs to match the cam. Alum. rockers, long hooker headers, dual flowmaster series 40 exhaust and and MDS ignition system. I'm also going to add an X-pipe to the exhaust. Had a valve job done on it as well.

Never dyno'd it, but I might once I finish the work and am actually home long enough to do so.
 

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Definitely for a 289 driver you are going to want to stay below 600cfm. When you get too big of a carb on an engine you can experience hesitation and flat spots.

Also, try and stay away from Pony Carburetors. They are nothing but a headache/waste of money for myself and several others.
 

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Okay, so reading everybody's responses on here, do you think with the changes I listed on mine that a 570 - 600 would respond better after a little more testing than the 650?
 

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I've got a 68 mustang with a 289 and i am thinking about putting an edelbrock carburetor on it but in not sure which one to use, can anyone tell me what the difference is between the 1405 and the 1406? And maybe which one they would recommend that i should use! I would appreciate it!

1405 is manual choke and 1406 is electric choke.

1405 is also stock caliborated for performance whereas the 1406 is stock caliborated for fuel economy. Very easy to change the metering rods and jets on edelbrocks. Good carb to go with.
 

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If you do go a little too big, it does help that you are running a 4-speed rather than an Automatic. You would have less chance of stalling because you are using a clutch.
 

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I'm running the same 575cfm Demon carb on my '66 coupe and love it. I have no complaints. It looks awesome sitting on top of the engine. The mechanical secondaries are best suited for a standard tranny car like I have. I've experimented with many carbs in the past ranging from 450 cfm to 750 cfm Holleys. Surprisingly, a 3310 Holley(750cfm vac secondaries) yielded the best gas mileage. I get 14 mpg with the Demon. The 750 Holley acheived 16mpg on the highway. Around town, both do about the same....8:happyhapp.
 
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