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Discussion Starter #1
Hey everyone
how good are Demon carbs compared to Holleys and Edelbrock. I have a Stock 1968 289-2v and I was looking at the Road Demon but I dont know if I should just settle for a plain old 600 cmf edelbrock. Do you guys think that i can get 400 horses out of the old 289.
Thanks,
Kenny

By the way, what is a choke and why is everyone cutting them off in this forum
 

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The Edelbrock is OK for putting around on the street, but, if you want to make the most power, get the Demon or Holley. I've seen more than one street car swith from an Edelbrock to a Holley of the same size and gain 2 to 3 tenths in the quarter.
Just my unscientific opinion.
 

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400hp out of a 289ci. One word....STROKE....
I have a 600 Ebrock on my 302 in my boat and it works fine...I will be putting it on my 347 when it's done....Demons look hot,,and will make more power than the Ebrock....I would like to see a dyno shoot out between Ebrock carb and demon or holly,,just to see how much power difference there is...Russ..
 

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Discussion Starter #4
thanks for the replies, but I dont quite understand the difference between vacuum operated-secondaries and machanical operated-secondaries? Which is better? Which one allows for super/turbocharging???? also I dont quite understand what a choke does and why people are cutting them off of their carbs.
thanks,
kenny
 

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Well, mechanical secondaries means the back two butterflies on the carb are opened mechanically by the throttle linkage.

Vacuum secondaries means engine vacuum pulls the secondary butterflies open, the engine only gets as much air as it can pull in (assuming the carb is big enough) on vacuum secondaires.

A choke is exactly that. It chokes the air to the engine making it run richer on cold startup. A race engine doesn't need a choke because it restricts airflow into the carb and you can just give the throttle a few jabs to richen up the charge before you start the engine. Without a choke you will have to let the engine warm up before you put it under a load. I hope this helps your understanding of chokes and secondaries.
 

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Discussion Starter #6
thank you very much, that did help alot. Now im wondering which is better mechanical secondaries or vacuum secondaries. Im planning to <U>super/turbocharge</U> the 289. what are the benifits of mechanical secondaries vs. vacuum secondaries.

thanks,
Kenny
 

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If you are going to hot rod that thing your best bet is a DP, the difference is the secondaries are opened mechaniclly when you get past 1/2 throttle or so, the vacum secondary carbs are just that when vacum drops in your intake at WOT the secondaries open, the point at which the secondaries open on this carb can be adjusted with springs to open sooner or later. I have run both and the first time I bolted on a DP I new I would never go back.
 

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I agree that DPs are the way to go. When you stab the throttle, the secondaries go wide open. No doubts, no excuses. Nothing but throttle.
 

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Discussion Starter #9
do double pumpers start at 650 cfm? is that too much for a 289 considering a HiPo came with 480 cmf? Who makes the best double pumpers and can they be turbo/supercharged?
thanks alot,
Kenny
 

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Discussion Starter #10
anyone know of any superchargers that fit under the stock hood of a 68 mustang?
 

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Tried the Road Demon, then the Street Demon. Both ran too dang rich for the street. Demon sent me little inserts to lean the idle but I never could lean it out. Other than that they weren't bad, but I'd stick with a Holley or Edelbrock if you're using it on the street...........
 

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If you want to supercharge and stay under the hood, then Paxton makes a unit that can still be used with a carb. Your carb. will need to be modified with implosion resistant floats to withstand the boost. I understand the appeal of Turbo/Supercharging, but for what a supercharger costs you can build a very strong RELIABLE normally aspirated engine. Supercharge a stock engine without building it for boost and sooner or later you'll be sweeping up parts. Just my opinion...
 

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Holley makes a roots type supercarger for 289-302's, I dont think it will fit under the stock hood (a tear drop or cowl hood may be nesisary). If you want to keep the stock hood you will probably have to go with a centrifical supercharger, Paxton makes a kit that bolts on to early Mustangs(it is the same one used on the supercharged Shelby's). The Paxton kit requires a specially modified carburetor, so you might want to talk to Paxton before you buy a carb. Vortech recently released a centrifical supercarger kit for carbed vehicles but it may only be for chevies. Overall I have been told that centrifical superchargers and turbo's can be pretty tough to tune using a carb(as opposed to efi) and that positive displacement or roots type supercargers are easier to tune using a carb. I have done neither, but this is what I have been told.
 

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Once you figure out what you're going to do, (i.e. supercharge/turbo/whatever), and get your complete combo list together, give Jesse and Lynn @ Biggs a call, if you're going to run any sort of carburetor.
First things first tho. Don't get the carriage in front of the horse.
It's much easier to build a complete system once, and do it right then it is to piece something together 5-6 times going in every which direction, and finally deciding on a path, only to find out nothing will work with each other. (i.e. mismatched parts, etc. etc. etc).
My .002..............and that ain't worth much..........
 

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Discussion Starter #15
so do you guys think i should go blown or strok. wont both put about the same amount of strain out of the 289. How many hourses do you think i can squeez out of it.
Kenny
 

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Discussion Starter #16
is the 289 even a good engine and is it worth the trouble of supping up for that matter?
kenny
 
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