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Discussion Starter · #1 ·
I currently have a Holley ultra 650 dp with mechanical secondaries, and for the life of me I just can't get it tuned right. I've read reviews where people have had problems with these carbs. So I'm currently looking at a new vacuum secondary carb, the one that really catches my eye is the new demon 625. I read reviews and so far everything is good. Has anyone here heard or used one? Here is a link
Demon Carburetion Street Demon Carburetors 1901 - Mobile SummitRacing.com
 

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I haven't used a Demon since Holley bought them. Do you know if they're the same design, or if Holley changed them?

I had 2 different Demon carburetors back before they sold, and I hated them. I couldn't get those things to run worth a damn, and I spent a lot of time trying. That said, I know a few guys that run them and are happy with them.


What problems are you having with the Holley? If you get a mechanical secondaries to work, you'll love them.
 

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what are you gonna do with the holley if you get that one?
what are you having trouble with?
 

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Discussion Starter · #4 ·
It has great wot performance and it idles good, but part throttle drivability sucks. It bucks and surges while cruising. I've tried different jets, different squirters, changed power valves and nothing helps. I'm not sure what ill do with the holley if I change it.
 

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Well squirters have nothing to do with part throttle. Did you adjust the float level? what jets are in it?
 

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I had 2 Demons a 575 Speed Demon & a 650 Mighty Demon, both carbs sucked!! I sold them & went with a Quick Fuel 650 Hot Rod series. It runs great, but is rich @ part throttle crusing. I've also changed everything from jets, power vavles, high speed air bleeds, etc. I'm now going with a EFI Spyder intake & Edelbrock 4 Bbl. throttle body, controlled with a Mega Squirt II! I've had my fill with carbs on my drivers!!

I personally wouldn't recommond a vacuum secondary car on a manual trans car. Every time you shift, you have to wait for the secondaries to open!
 

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I had 2 Demons a 575 Speed Demon & a 650 Mighty Demon, both carbs sucked!! I sold them & went with a Quick Fuel 650 Hot Rod series. It runs great, but is rich @ part throttle crusing. I've also changed everything from jets, power vavles, high speed air bleeds, etc. I'm now going with a EFI Spyder intake & Edelbrock 4 Bbl. throttle body, controlled with a Mega Squirt II! I've had my fill with carbs on my drivers!!

I personally wouldn't recommond a vacuum secondary car on a manual trans car. Every time you shift, you have to wait for the secondaries to open!
Quitter!


Lol
 

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Discussion Starter · #9 ·
It has 63 primary and 73 secondary, which is factory. I've went down and up in size. Those work the best. It came with 31 primary 28 secondary squirters, now it's got 35 primary 31 secondary. And a 6.5 power valve
 

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