I am looking at a Demon carb for my zz3 with 1 3/4" headers, Tremec 5 speed and 3.55 gears. Anyone work with them before? How do they compare to Holleys? Any difference in performance(HP and 1/4 mile)? Thanks.

Welcome to our site! I run a Speed Demon 750 on my 388 and really like it. I picked up 1/10th right out of the box over my well tuned Holley 750 vac sec carb. I actually played with the Demon a little but the fastest ET's so far have been with the factory jets, etc.

ps. Probably a Demon 650 would be about right for your ZZ3. If you had a radical cam and big heads than you might be able to get away with the 750.

[This message has been edited by Eric68 (edited 11-22-2002).]

I use the Road Demon (625cfm), and I love it. Very smooth, I honestly say it's like fuel injection.

I've spend alot of time tuning it though. They are very sensitive carbs, which can make it somewhat frusterating. I would never go back to my Holley 4150.

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Matt Jones
1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my webpage at: http://www.geocities.com/compuboy007/

The best carburetor I have ever used out of the box. I have one on my ZZ430 in my Jeep (a 650 race demon) and one on a ZZ3 in an '89 vette that I built for a friend.

Extremely tunable, as responsive as fuel injection and simply unbeatable (in my humble opinion).

On the other hand, you can also get them messed up pretty quickly if you think that you know better than Barry....

I have a brand new Road Demon on a ZZ4 that I have been fighting for weeks. I finally took it to another guy. He found the choke butterflies were off centered and had to reset them. The throttle butterfies were also off center and they had to be reset. The accelerator linkage had to move quite a bit before it pushed on the pump and the spring had to be shimmed to get the pump to work when the accelerator was pushed. The secondary linkage couldn't be adjusted to close the secondaries at idle. He ended up bending a new linkage piece that was a little longer that would push the secondaries closed (like a Holley). But, he said when he got through and drove it it seemed to be very responsive and seemed to run well. He still can't understand why I didn't buy a Holley.

I bought an 850 years ago for my rat motor, it is a vac. secondary. Clearly, it is a well thought out piece. I did have a problem though, the throttle linkage had a burr on it that caused a bind on the throttle plates. This happened on the street, of course, and caused the motor to stick at 3000 RPM. Ever try to stop a 550 HP full body Chevelle, with manual drum brakes? White knuckle fever.

as many of you that regularly read this have seen, im all for demon carbs. i'm running a 750 speed demon dp on my 406, and it starts and runs killer, everytime, even if the car has sat for weeks. i totally agree w/ silver69, its the next best thing to fuel injection. i also found, oddly enough, the same as eric, my set up seems to like the factory jetting, if anything its a touch rich. thats on a solid roller 406 w/ 220cc heads, and 11.6:1 comp. can't say enough about idle quality and throttle response. as far as size for your application is concerned, if you don't plan on upping the performance much from what it is now,(yeah, that never happens http://www.camaros.net/forum/biggrin.gif), a 650 is probably fine, but if uprgrades are in the future, don't be afraid of the 750. i actually ran my 750 on my tired old 350 before i put in the 406, and it ran great! thought it would prob. be overcarbed, but it started and idled better, and was far more responsive than the quadrajet that was on it. (and yes the quad was tuned fine and ran o.k.)just my .02, good luck!

using a race demon.. aside from a surge at light throttle openings..its perfect.

My 69 has a ZZ430 in it with the Holley 750 Vac. Sec. 1 3/4" Supercomps, (Don't have exhaust in yet! reading other posts before I make up my mind) I've been thinking of the Demon double pumper as a replacement. I e-mailed Demon and asked what size was best. They replied and said a 650! I think It's a bit small. The Demons are supposed to atomize fuel better that the Holley? I just don't want to spend the money for a 650 DP. and find out later that I should have bought a 750. Anybody have any thoughts?
Thanks
Jim

Jim,
I think your carb is fine, i think you should AT LEAST try it out and tune it at the track before anything, so when (if) you change carbs you know whether the new carb did anything for your ET's.

Thanks for the reply
You're right, I should try it at the track before I get all excited and blow more money.I got amazing dyno numbers with the Holley. I bought the Holley because it was the carb of choice for the limited edition ZZ430.(mine is a clone) But,I've been doing some reading on the Demon and feel that I may have made a mistake. Oh well, I worry too much anyway. It's only money.
Jim

I was looking into a new carb,and it sounds like a demon carb might be the way to go.I was wondering what size you guys would suggest.My car is a daily driver,this is the combo:

350
trick flow 23degree heads
scorpion 1.5 roller rockers
performer rpm intake
dynomax cerama coated 1 5/8" headers
10:1 compression

Thanks