Demon 625 - anybody running one? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dznucks · 10-17-2007, 09:02 AM

i put a road demon 625 in my c10 not long ago. i have a mild jasper 350 and have been running it for about 6 months. it seems i have never got the thing to run just right, never backfires just stumbles and bogs down. i feel like i have the idle screws adjusted and the timing right. but it seems like i dont have the power i used too. when you slightly get on it you can feel the motor bog as if the mixture isnt right. Does anyone have any experience with this issue or does anyone have any suggestions on what to change or adjust. i am no expert at carbs. but i feel like there is some power that is benig held back by something simple.

also can anyone give me some good advise on setting the fast idle screw and the choke. winter is fast approaching and if i don't get it adjusted its going to have some rough starts this winter. i have made several attemps but never got it right.

thanks

70c10 · 10-17-2007, 09:08 AM

I have one and am happy with it

. You have to let it idle for about 15 seconds before touching the throttle for the choke to work right. I just installed a new air cleaner and may have to grind a little out of the air cleaner base to make sure the linkage is not rubbing. Since I installed the new air cleaner it takes longer to warm up. I'm planning to remove the air cleaner as a test. Did you buy it brand new or used? You should call BG.

dznucks · 10-17-2007, 09:16 AM

I bought it new. i have called BG but their customer service is lacking.
how did you set the choke and fast idle setting initially?

shopking72 · 10-17-2007, 09:19 AM

I have a 625 Demon also on my truck. I was not happy at first cause I couldnt get the electric choke to work, but me and my dad figured it out and now it runs great!

They make a big book that is all about tuning Demon carbs, I have it, you can get it at Borders.

dznucks · 10-17-2007, 09:23 AM

thanks shopking.

i'll check it out.

dznucks · 10-17-2007, 09:31 AM

Shopking
whats the title of that book? i didnt see it.

70c10 · 10-17-2007, 12:57 PM

Look here:http://sabooks.carshopinc.com/produc...s_id/46875/68:)

I had mine tuned 2 1/2 years ago by someone locally. Made a BIG difference!

jkaylor68gmc · 10-17-2007, 01:34 PM

I have one on my '68, It runs great out of the box.

14U2NV · 10-17-2007, 03:19 PM

I have one on my '78 Malibu. I'm not going to knock it too bad as it is running strong now, but...... When I first got it, it just would not tune. It was sloppy rich. I did every trick I knew and my dad did as well. I started to do some research online and found out the quality control was not very good at BG. Lots of stories of metal shavings etc. So, short story long, I took my apart and found the shavings. I also had to de-burr the metering blocks. One of the blocks even had double gaskets that were "out of alignment" covering most of the holes. Needless to say, it runs one heck of alot better now. Will I buy a new one again, most likely not. I might buy a used one cheap now that I know how to "tune" one.

c10addict · 10-17-2007, 10:19 PM

I am in a local car club www.hwknights.com (plug lol) and the general feedback is stay away from them... I have heard about many tuning issues.... There are a rare few that have bought and loved them... I never had one because I do not want to take a chance.. I'll stay with the old faithful Holley...

short69 · 10-18-2007, 12:01 AM

i have a 750cfm on a 400 small block and it also acts funny until its plenty warm-after that it works fine.

10-17-2007, 09:02 AM	#1
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Demon 625 - anybody running one? i put a road demon 625 in my c10 not long ago. i have a mild jasper 350 and have been running it for about 6 months. it seems i have never got the thing to run just right, never backfires just stumbles and bogs down. i feel like i have the idle screws adjusted and the timing right. but it seems like i dont have the power i used too. when you slightly get on it you can feel the motor bog as if the mixture isnt right. Does anyone have any experience with this issue or does anyone have any suggestions on what to change or adjust. i am no expert at carbs. but i feel like there is some power that is benig held back by something simple. also can anyone give me some good advise on setting the fast idle screw and the choke. winter is fast approaching and if i don't get it adjusted its going to have some rough starts this winter. i have made several attemps but never got it right. thanks Last edited by dznucks; 10-17-2007 at 09:04 AM.

10-17-2007, 09:08 AM	#2
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Re: Demon 625 - anybody running one? I have one and am happy with it. You have to let it idle for about 15 seconds before touching the throttle for the choke to work right. I just installed a new air cleaner and may have to grind a little out of the air cleaner base to make sure the linkage is not rubbing. Since I installed the new air cleaner it takes longer to warm up. I'm planning to remove the air cleaner as a test. Did you buy it brand new or used? You should call BG. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

10-17-2007, 09:16 AM	#3
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Re: Demon 625 - anybody running one? I bought it new. i have called BG but their customer service is lacking. how did you set the choke and fast idle setting initially?

10-17-2007, 09:19 AM	#4
shopking72 Registered User Join Date: Sep 2005 Location: Kansas Posts: 774	Re: Demon 625 - anybody running one? I have a 625 Demon also on my truck. I was not happy at first cause I couldnt get the electric choke to work, but me and my dad figured it out and now it runs great! They make a big book that is all about tuning Demon carbs, I have it, you can get it at Borders. __________________ 1972 C10 LWB- 4.5 Front and 5 Rear Drop, 406/TH350 1966 Caprice 1968 Impala (Frame Off LSX Project) 2001 Tahoe LT 2013 Hyundai Elantra 2010 Kawasaki Z1000

10-17-2007, 09:23 AM	#5
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Re: Demon 625 - anybody running one? thanks shopking. i'll check it out.

10-17-2007, 09:31 AM	#6
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Re: Demon 625 - anybody running one? Shopking whats the title of that book? i didnt see it.

10-17-2007, 12:57 PM	#7
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Re: Demon 625 - anybody running one? Look here:http://sabooks.carshopinc.com/produc...s_id/46875/68:) I had mine tuned 2 1/2 years ago by someone locally. Made a BIG difference! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

10-17-2007, 01:34 PM	#8
jkaylor68gmc Senior Member Join Date: Dec 2005 Location: TN Posts: 2,448	Re: Demon 625 - anybody running one? I have one on my '68, It runs great out of the box. __________________ 1947 International KB-1 1957 Chevy Bel-Air riding low 1962 swb fleetside 2002 Chevrolet Silverado 7-inch lift on 35 Daily driver 2016 Chevy Tahoe Better halves ride

10-17-2007, 03:19 PM	#9
14U2NV Registered User Join Date: Mar 2002 Location: Midlothian, Tx Posts: 156	Re: Demon 625 - anybody running one? I have one on my '78 Malibu. I'm not going to knock it too bad as it is running strong now, but...... When I first got it, it just would not tune. It was sloppy rich. I did every trick I knew and my dad did as well. I started to do some research online and found out the quality control was not very good at BG. Lots of stories of metal shavings etc. So, short story long, I took my apart and found the shavings. I also had to de-burr the metering blocks. One of the blocks even had double gaskets that were "out of alignment" covering most of the holes. Needless to say, it runs one heck of alot better now. Will I buy a new one again, most likely not. I might buy a used one cheap now that I know how to "tune" one.

10-17-2007, 10:19 PM	#10
c10addict Registered User Join Date: Aug 2007 Location: pittsburgh pa Posts: 1,970	Re: Demon 625 - anybody running one? I am in a local car club www.hwknights.com (plug lol) and the general feedback is stay away from them... I have heard about many tuning issues.... There are a rare few that have bought and loved them... I never had one because I do not want to take a chance.. I'll stay with the old faithful Holley... __________________ 68 C10 Shorty TPI,Bagged, and all the good stuff. Classic trucks feature June 06, On the cover of Jegs Christmas Catalog 08 67 C10 Shorty Shop truck project Bagged and Z'd under destruction and getting nowhere fast. 64 C10 Shop Truck/Daily driver, Bagged, Dropmember, SOLD!!!! Gone but not forgotten.. 54 GMC under the knife getting a S10 chassis swap and bagged. See my build thread... 07 GMC Sierra 5/7 drop, 22's and 24's Air ride on my mind.. http://67-72chevytrucks.com/vboard/s...d.php?t=339340 See pics of my trucks in my profile

10-18-2007, 12:01 AM	#11
short69 Registered User Join Date: Oct 2006 Location: las vegas Posts: 88	Re: Demon 625 - anybody running one? i have a 750cfm on a 400 small block and it also acts funny until its plenty warm-after that it works fine. __________________ 69 shorty w/ 67 front clip



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