holley or demon carb

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mopardemon340

mopardemon340

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need some input on a new carb for our 408 build.. right now i have a holley 770 on my 340 and im going to try it on the 408 when we go to the dyno. but i want some input on weather i should go with a 850 holley or demon. the 408 should push between 450 to 500hp and will be run with a auto trans. we will also be trying an 820 demon to see what give the best proformance.. what would you recommend and why?
 
850 demon,850 holley are pretty much identical minus the smooth looks of a demon. I bet both new are about the same. Holleys are like android phones. Everyone makes stuff for them at varying quality standards and they are so highly adjustable that they end up not working as well as out of the box after they are F'd with. Carters are more like I-phones...they just work.
 
Demon carbs S.U.C.K...like Mike said get yourself a Quickfuel been running a 850 on both my 360 and 416,performing flawlessly and will be running it on my
"new" 340 build..have tried just about all of them.. Quickfuel is the best I ever bought:thumbsup::thumbsup:
 
ok what makes the quick fuel so nice. i am open to suggestions
 
first and foremost - mine worked right out of the box - no BS. Bolted it up, plumbed it and done. I have the 750 "race" - chokeless.
 
i have only ever used holley so please explain the quick fuel holley.. profromance, quality, response and any thing else
 
Doesn't Proform make parts for Quickfuel?

Very happy with my Proform 750 so far for $330, lots of great features without the sticker-shock.
I am very interested in learning to tune it, though.
 
just found a video for the quick fuel and it looks really nice and there are a lot more to it that can be adjusted.
 
ScampMike said:
first and foremost - mine worked right out of the box - no BS. Bolted it up, plumbed it and done. I have the 750 "race" - chokeless.
Click to expand...

Mike. is right no BS..right out of the box my 850 performed. I've done nothing to it but play with jets depending on the weather..my demon was a piece of **** spent more time trying to adjust it,make one adjustment another one another one ect ect. total garbage!!!
 
the thing about quick fuel and a proform is they they come with billet base plates,billet metering blocks and a ton more adjustment then a holley. plus they are usually cheaper then the holley
 
here is the 750 profrom that was on my 71. opened the idle air bleeds some and adjusted the jets. other then that it didn't need a thing...
DSC06178.jpg


here is the 650 proform on jamies 70.. all i've done so far is open the idle air bleeds and adjust the choke.. will probably change the primary jets too but that will wait for now.. runs awesome. its one of their "street" carbs..
DSC_0003.jpg
 
mine is mechanical with a 727... IIRC there are other considerations when choosing between vac or mech
 
i remember years ago when demon carbs were the big deal to have a ton of people complaining about metal shavings int he float bowls..
 
did a quick search - For street cars the vacuum secondary carburetor works best on most cars with an automatic transmission. ... The mechanical secondary carb is best on a lighter car with a radical camshaft, a lower gear, and manual transmission. A mechanical secondary is the best choice for most high RPM race purposes.
 
i don't know about all that.. our mild 360/904 with 2.94 gear runs awesome with a double pumper..
 
well its a demon car so its light, 373 rear, cam 565 lift 286.6 duration
 
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