Thoughts on Demon carburetors - Chevelle Tech
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post #1 of 13 (permalink) Old May 17th, 19, 7:34 AM Thread Starter
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Bill
 
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Thoughts on Demon carburetors

I am currently running a vacuum secondary 3310. My build is in my signature line. Chris Straub recommended an 850 for it so I tried an 850DP. It made 12 more HP on the dyno but I really didn't like it on the street, thought it was a little lazy even though I spent a lot of time dialing it in as best I could get it but I really like my 750 better and feel that an 850 vacuum might be a better choice. I have a chance to buy an 850 vacuum secondary Demon for 1/2 the cost of a new one from a guy who converted to fuel injection for his pro touring Chevelle. Anything particular I should now about? Thanks.

Bill
_____________________________________________
'65 Buick Skylark,
406 sbc, 10.07 comp, ported Trick Flow 195 heads, RPM Air gap, Holley 3310, Straub HR .547/.516 233/243, Hedmans, 200-4R, 10" 3,200, 4.10 12 bolt.....and factory a/c
http://s1085.photobucket.com/albums/...t=Buick007.jpg
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post #2 of 13 (permalink) Old May 17th, 19, 8:05 AM
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Re: Thoughts on Demon carburetors

I ran an 850 Demon mech secondary on my ZZ502 for a summer. I really did not like the carb. Tried different jets etc. but it never really worked well. It also seemed to be cheaply made.Switched to a Quick Fuel 950 and it works great.
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post #3 of 13 (permalink) Old May 17th, 19, 8:39 AM
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Re: Thoughts on Demon carburetors

I've had great success with Demon carbs...large and smaller ones.
Even the newer Holley produced ones run awesome.

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post #4 of 13 (permalink) Old May 17th, 19, 9:14 AM
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Eric
 
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Re: Thoughts on Demon carburetors

Hi Bill, I've had a Demon 825 mechanical secondary on my 468 for about 9 years with no complaints. Like you I purchased it second hand for half the price of a new one. I've read several posts on this site and other about problems with Demon carbs, but I haven't experienced any problems. Good luck with your project!!
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post #5 of 13 (permalink) Old May 17th, 19, 9:37 AM
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Kerry
 
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Like many other holleys it will need emulsion changes, relocate the IFR and likely smaller than as delivered. The good thing is that all jets are threaded in them so easy to calibrate by drilling your own jets. A set of pin drill bits, and brass set screws from McMaster Carr is all you need.
I suggest contacting jmarkaudio for baseline calibration ideas.
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post #6 of 13 (permalink) Old May 17th, 19, 6:21 PM
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Re: Thoughts on Demon carburetors

I ran a 850 Demon on my 496 until I went to EFI. Demon worked perfect. Infact I feel the Demon was faster at WOT.

64 Chevelle 496
64 F100 Street Rod with BBC /Chevy trapped in a ford body
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post #7 of 13 (permalink) Old May 17th, 19, 6:32 PM
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Re: Thoughts on Demon carburetors

I have 6 Demon carburetors and all of them work great for me. I am really impressed with annular discharged ones, work much better then the Holley annular's that I have tried in the past. I mostly race with the 850 Mighty Demon and it has out shined my old tricked out 750 Holley DP that I used for a long time. Last one I got was from an old guy that said he had an Edelbrock Demon carb for sale. I had to go over there as he did not have a clue to what it was, turns out the stock 350 had a 750 Mighty Demon on it, the y gut told me to give him a $100 and get it out of his garage he hated it so bad. Got it home and it was setup pretty bad, gave it a good cleaning, gaskets and adjusted it put it on my 461 it fired right up and runs great. I guess it's just something else to test at the track.
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post #8 of 13 (permalink) Old May 18th, 19, 7:29 PM Thread Starter
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Bill
 
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Re: Thoughts on Demon carburetors

Thanks for the replies. I went and bought it today. Now I just have to find time to get the car in the shop to swap it on and a couple other things on my list.

Bill
_____________________________________________
'65 Buick Skylark,
406 sbc, 10.07 comp, ported Trick Flow 195 heads, RPM Air gap, Holley 3310, Straub HR .547/.516 233/243, Hedmans, 200-4R, 10" 3,200, 4.10 12 bolt.....and factory a/c
http://s1085.photobucket.com/albums/...t=Buick007.jpg
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post #9 of 13 (permalink) Old May 19th, 19, 1:47 AM
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Kerry
 
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https://www.tapatalk.com/groups/raci...ms/holley-f25/

Join this forum and ask for some baseline set up on it.
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post #10 of 13 (permalink) Old May 19th, 19, 6:21 AM
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Mike
 
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Re: Thoughts on Demon carburetors

I had an older BG Race Demon dp on my big block with a 600/600 cam. 4 spd. Ran and idled great. I sometimes wish I went a little bigger. I was always told back in the old days a double pumper for a stick car and Vacuum for an automatic.
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post #11 of 13 (permalink) Old May 19th, 19, 7:59 PM
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Jason
 
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Re: Thoughts on Demon carburetors

I went from a 4779, 750DP to a 850 Mighty Demon Annular I got for $500 and after lots of tuning it ran good but my old 750 still felt better on the street. Wish I would have gotten a 750 Mighty Demon or Holley 750 XP.

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Budget 454, 10.4:1, small valve 781's, Engle hyd cam 244/260 @ .050, .560/.570 lift ICL/LSA 108/108, Performer RPM w/ 750DP
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post #12 of 13 (permalink) Old May 20th, 19, 1:55 AM
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Re: Thoughts on Demon carburetors

Dont you have to change the springs on the distributor also?

Sometimes you just cant swap a carb...

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post #13 of 13 (permalink) Old May 20th, 19, 2:11 PM
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Ray
 
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Re: Thoughts on Demon carburetors

I could be wrong, but I don't think you're going to like an 850 vacuum squarebore carb. Your combo screams a decent 4779 750 holley

Ray
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