OkeeGuy

do you like it?
what is the good?
what is the bad?

02electronblue

ttt

Corz

I had a Road Demon with the electrical choke (same basic carb).

BEST money I ever spent on the car. the throttle responce was amazing, it was like I added 50 horse to the car. it REALLY woke it up.
Drive-ability improved tons. it would get up and go on demand and not once did I have to re-tune it.

the bad? I noticed a significant decrease in gas mileage (I think thats because my foot got heavier) :smash:

Mystery Machine

I have one. 650cfm with elec. choke and vac. secondaries. I like it a lot. I'll tell ya this. I had an Edelbrock (not to bash them...it was a great little carb but it was just that, too little only 500cfm). I used to have trouble spinning the tires (with a ZZ4 in there). I used to have to use the brake to get them going. After bolting on the Demon I took it out for a test drive and left a 10' black patch without using the brake. Then barked them in second (I have a TH400 auto tranny with no shift kit at the time).

In short...very good carb. Well worth the $$ in my opinion.

no_radio

I have a Speed Demon 650 mechanical secondary with no choke on my '74. With the 350 and 4-speed I can pull a 1.88 60ft on street tires, and a 8.11 @ 87.5 mph in the 1/8 mile. Much better throttle response than with my professionally rebuilt Qjet. The only thing is I haven't quite gotten the idle mixture the way I want it, it requires more than just sdjusting the screws. I think I need to re-read the instructions and start over on the idle mixture setting, but the car is WAY faster than before. My knees were shaking the first time I drove it with the Demon.
Also have a Speed Demon, 750 vacuum secondary on my 454 Suburban. Same deal, way more power, better throttle response, excellent carb.
Jeff

OkeeGuy

man...everything sounds positive so far...
Lars has recomended the Speed Demon 750 with mechanical secondaries for mine...
no choke needed here...(i was swimming last night at 2am!)
can they be bought without a choke?

what else will i need...as in fuel line connection etc?
i have an Edelbrock Performer intake...

will this air cleaner that i am running on my Edelbrock fit on the Demon? http://store.summitracing.com/partde...4221&view=1024

also...what kind of fuel pressure does it like?
im puttin out 6-1/2 lbs...unregulated...

thanx everybody... :)


[Modified by SIGNGUY, 7:17 AM 2/5/2004]


[Modified by SIGNGUY, 8:32 AM 2/5/2004]

gkull

I have the 750 SD chokeless and would only recommend them for 383 and above unless your running a dual plane intake.

Mystery Machine

Be careful about air cleaners. If you end up getting one with a choke they have a funky little arm that gets in the way of the base of the aircleaner. You'll have to check the one you are running now with it or go to a shop and test fit unitl you find one that works. If you go chokeless you're fine.

69schemers

Does anyone know why Lars recommends the mechanical secondary 750 over the vacuum secondary? I would think the vacuum secondary would be better with fuel mileage. Also living in Michigan, we don’t have many warm mornings.

lvrpool32

I have the 750 MS, absolutely love it.
Performs well...and it polished up real nice :D

Last Place

I'm glad you asked, check out this link:

http://forums.corvetteforum.com/zerothread?id=744248


[Modified by Sling Blade, 9:25 AM 2/5/2004]

Last Place

BTW, you mentioned you have a Performer intake. Have you thought about stepping up the the Performer RPM?

Ganey

Demon Selection Guide
http://www.demoncarbs.com/demon/default.aspx?page=5

No :reddevil here.

:blueangel: :cool: :blueangel:


[Modified by Ganey, 8:46 AM 2/5/2004]

Ken74Conv

I'd like to know if anybody has compared the Demon to the Holley.
I have a 670 Holley avenger on my ZZ4.
Would I notice a big difference if I went to a Demon?
:confused:

Ganey

Here's one.
CARBS Tests TQ/HP http://www.corvettefaq.com/c3/carbcomparo.htm

Blkblt

My 1966 L72 427 (dual plane intake) originally had a Holly 780. That POS has been in the parts box for years. I have run Holly VS with and without choke, a 750 BG Speed Demon VS with choke, a 750 mech/sec without a choke, and the present 850 BG Speed Demon mech/sec without choke. Performance has increased up the line with each change. The present 850 tops them all!! :yesnod: Lars has my old BG 750 mech/sec on his '64 350, and it made a huge difference on that car. I think there is a lot of street myth out there regarding over-carbing some of these older performance engines.

Personally, I think the BG mech/sec carbs are the easiest out there to baseline, set-up and tune. You can visually see the float levels, and as long as the baseline set is correctly and you start with all idle mix and idle screws at base, those adjustments are simple. While I had to down-size my jets in the 750 for our altitude, the 850 was right on out of the box. While my VS carbs opened ok at this altitude, I just never liked the slight bog that goes with them when you get on it. The mech/sec BGs have a seamless transition...and you KNOW they are open! Gas milage????? In a 427???? :lol: :lol: Do I care ?? :rolleyes:

Modifications: I had to remove the vent tube running from the base plate of the large air filter to allow room for the pump arm on the secondary side. No big deal there. The next caretaker can easily replace the base plate (and reinstall the correctly numbered Holley if he or she has no care about performance). BGs don't come with fuel lines; purchase the set-up separately. Lars built a line and in-line filter from the fuel pump to the commercial BG line....as he as done with most of the CCCers Vettes.

Chokes: I haven't a thing against a well set-up choke. I have just found that I don't need one. With an MSD ignition system, I can go into my unheated garage, give the pedal a couple of taps, and the old 427 explodes to life every time, regardless of temperatures. I just need to stay with the car a minute or two longer than with the choke system. Presently, the front range of Colorado is snowed in and my thermometer is reading 15 degrees. Personally, I think that a finely tuned carb probably doesn't need a choke. One that is out of tune.....and lots of them are that...might benefit from a choke for starting.

Just my 2 cents. :cheers:

********************

********************
Jeff; Charter CCC
1966. Modified L72
The Silver Beast
Keep on :cheers: :seeya :flag :steering:

LFZ

I guess i'm the only one here who had bad experience with the 650 Speed Demon. My neighbor had a 750 Demon on his 55 chevy and hated it too. Best thing I did was get a Holley, but I wouldn't mind trying another Demon though.

Sigforty

I have the 650 for a ZZ4 on my car. It has mechanical secondaries. It was the best thing I have done. The new Demon is even better than the old one I had. I really like the carb, and would not try anything else on my car at this point.

lars

2 best performance improvements I have done to my car ('64 Roadster with a 350):
1. Rebuild, curve and set up the distributor right
2. Install and set up a 750 Speed Demon mechanical sec carb with heat shield.

Corey_68

I have a 850DP on my Big Block and I will NEVER buy a Holley or Edelebrock carb again (for a performace carb). :thumbs: