Which Demon for my 383 - 650 cfm or 750 cfm? [Archive] - Team Camaro Tech

: Which Demon for my 383 - 650 cfm or 750 cfm?


Hurst - Jeff
Jul 13th, 04, 10:49 AM
Hello-
I need some opinions on which carb to select. Here are the facts:
Brand new 383, AFR 195's w/68 cc, Comp Cams XE274H flat tappet cam, Hooker Super Comps, edelbrock RPM Airgap, 5 speed Tremec TKO manual transmission. The car is a weekend fun car (not a daily driver), it needs to be streetable but I want the upper end uf street performance for weekend speed. I do not plan to race it.
I am going to go with a Demon carb so my question is - which Demon carb is best for this set up? I am considering the following models:
Speed Demon 750 (mechanical secondaries)
Speed Demom 650 (mechanical secondaries)
Mighty Demon (mechanical secondaries)

I called Barry Grant Tech two times and the first guy recommended the Speed Demon 750. The second time I called a different guy said the Speed Demon 650 or the Mighty Demon 650 would be best?

Which one should I choose?

Thanks.

67RS502
Jul 13th, 04, 10:52 AM
Looks like BG dont know himself, wouldnt be the 1st time.
750speed graemlins/thumbsup.gif

Eric68
Jul 13th, 04, 01:51 PM
Definately the speed demon.

I think you could go with either the 650 or 750 -- maybe depending on what you might do with the motor down the road. If you think it might evolve into something more radical get the 750 -- otherwise the 650 would probably be just fine and might possibly have slightly better low end throttle response.

I use the 750 speed demon on my 383 and it is about perfect -- but my mill is a little more radical too . . .

Silver69Camaro
Jul 13th, 04, 02:31 PM
The guy you talked to the second time must have been new. They only recommend that carb for cams above about 245* duration.

Definetely 750 Speed.

railing68
Jul 13th, 04, 08:03 PM
Jeff talk to this guy fbo (http://www.4secondsflat.com/fuelsystems.html) ,the link works now. I spoke with him when I was going to buy a demon for my 383 and he recommended the 650 mighty demon. BG also said it would flow enough for 7k at our displacement I think wet-flow is equal to 730 cfm. He really seems to know his stuff and he goes through each carb prior to shipment. The prices are the same as Summit etc. Couldn't hurt to talk to him. SS

[ 07-14-2004, 06:58 PM: Message edited by: railing68 ]

Hurst - Jeff
Jul 14th, 04, 08:13 PM
Thanks everyone for the great input.
Jeff

CamaroJim
Oct 22nd, 06, 08:32 AM
Jeff, I was going to post a carb question but decided to do a related search first. I found your post from last July. What a coincidence. My 69 has the same engine, cam and intake although I am using dart heads. I also just installed a TKO 5 spd. I have a small prob with vibration in the rear u-joint but that's another story. I have to ask you which carb you chose. I am temporarily using an Edlebrock 600cfm that I had sitting around. I want to go to a BG but am unsure what to select.(650 or 750 speed demon) The TC guys have enlightened me to quality problems that I never imagined would have existed with BG.

fatblock
Oct 22nd, 06, 05:49 PM
Hello-
I need some opinions on which carb to select. Here are the facts:
Brand new 383, AFR 195's w/68 cc, Comp Cams XE274H flat tappet cam, Hooker Super Comps, edelbrock RPM Airgap, 5 speed Tremec TKO manual transmission. The car is a weekend fun car (not a daily driver), it needs to be streetable but I want the upper end uf street performance for weekend speed. I do not plan to race it.
I am going to go with a Demon carb so my question is - which Demon carb is best for this set up? I am considering the following models:
Speed Demon 750 (mechanical secondaries)
Speed Demom 650 (mechanical secondaries)
Mighty Demon (mechanical secondaries)

I called Barry Grant Tech two times and the first guy recommended the Speed Demon 750. The second time I called a different guy said the Speed Demon 650 or the Mighty Demon 650 would be best?

Which one should I choose?

Thanks.
Neither.You have a 180 degree manifold that needs to see more CFM.Your 383 will require at least 900 cfm to make peak HP and will operate fine seeing how half your engine is only feeding off two barrels at any one time.The hp series Holley would be a nice selection with stick car.