John Scott Posted November 28, 2002 Share Posted November 28, 2002 I really like the Demon carb, smooth power, no dead spots, instant response, except for the idle mixture circuit. Driving me crazy. Researching other sites the Demon carb has few fans with more complaints than not, often in this area of tune. I'm pretty comfortable with Holley carbs. The idle screws on this are so vague in their adjustment I'll never know what is "correct" It even runs with all screws fully in. I requested a manual from BG. Finding the drag sites prefer the HP holley series. Whish I had the $$ for one now. John Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 1, 2002 Share Posted December 1, 2002 John, how far open are the throttle plates at idle? Too far and the idle screws won't be effective. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 1, 2002 Share Posted December 1, 2002 I agree with Pete. Check that you are actually on the idle circuit. Disconnect the throttle cable if necessary. Tim Quote Link to comment Share on other sites More sharing options...
Mike C Posted December 1, 2002 Share Posted December 1, 2002 That's what I was going to say... Do you have a 4 corner idle setup or just the front? Pull the carb and flip it over to make sure that to get sufficient airflow that you have not uncovered the transfer slot. If you have just front idle circuit you can adjust the rear throttle blades for more airflow allowing you to cover the transition slot in the front. This will make your idle mixture screws function again. If you need more airflow at idle and have 4 corner idling then you may have to drill the throttle blades. If memory serves, however, your cam wasn't that big. If that is the case, most like adjusting the throttle blades on the secondaries will solve your problems. From the underside of the baseplate there is a set screw that you can turn in. I have hear that this can be pulled and put in from the top of the baseplate so the blades can be adjusted without removing the carb, but I have never tried it. You can attempt to experiment by blocking the rear throttle blades slightly open, dropping the idle screw WAY down then adjusting your mixture screws again. Quote Link to comment Share on other sites More sharing options...
Guest m35514h Posted January 14, 2003 Share Posted January 14, 2003 I hate to say it but i am a downer on demon. I was talking to my machine shop guy about getting one (650cfm) and he said they run 30hp under what holleys run on the dyno. Demon actually consulted him on why they do, and he has no idea as to why. Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 19, 2003 Author Share Posted February 19, 2003 I tired every trick in the book...including the Demon handbook. My cam, 244 @.050 .585, 108 pulls 12" at idle. It turns out air bleeds have been changed. anything more than 1/4 turn on mixture screws (4 corner)results in too rich. The penalty of buying a used dyno carb. I'm not hearing too many good things about these carbs. A few work well, but many have wierd gliches. I'm leaning towards the HP series 750 as it runs great right out of the box...unless of course you mess with it until it doesn't. John Quote Link to comment Share on other sites More sharing options...
Mudge Posted February 19, 2003 Share Posted February 19, 2003 Demon insists on advertising that they make more power though(?) Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 19, 2003 Author Share Posted February 19, 2003 Demon insists on advertising that they make more power though(?) I've now read many posts on the drag boards that would suggest most cars improve their times sustantially by replacing with same size Holley. There's a few, but not many Demon fans. I'm not one. John Quote Link to comment Share on other sites More sharing options...
Mike C Posted February 20, 2003 Share Posted February 20, 2003 Read here, then go spend money on 4779 Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 21, 2003 Author Share Posted February 21, 2003 Read here, then go spend money on 4779 Read where?? Better yet, tell me what you've read. John Anyone else having troubles with sig. pictures covering the text??? Quote Link to comment Share on other sites More sharing options...
Mike C Posted February 21, 2003 Share Posted February 21, 2003 Doh! Meant to reference this post right below... http://www.hybridz.org/phpBB2/viewtopic.php?t=17640 Just about everybody I knew who had a Demon went back to a Holley... Some excellent serious High-perf Holley carbs can be had from Divinci. For 99% of street cars, I think the 4779 is the way to go. If you REALLY need no choke and adjustable air bleeds, the 750hp. Quote Link to comment Share on other sites More sharing options...
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