Demon Carb question
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 62,198
Likes: 1
From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
Demon Carb question
I am looking at getting a speed demon 650 to replace my failing holley 650 double pumper
The way I understand it, is that I need mechanical secondaries with a manual transmission. Do I need to order their optional electric choke too? Or can I leave it chokeless? I dont think it comes with one as far as I can tell. Anybody have any advice on the issue
The way I understand it, is that I need mechanical secondaries with a manual transmission. Do I need to order their optional electric choke too? Or can I leave it chokeless? I dont think it comes with one as far as I can tell. Anybody have any advice on the issue
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 62,198
Likes: 1
From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Demon Carb question (Corey 68)
OK with the manual transmission does the mechanical secondaries really do much for me over the vacuum secondaries?
OK now to find out where I can get the choke
[Modified by Guru_4_hire, 8:31 PM 6/5/2003]
OK now to find out where I can get the choke
[Modified by Guru_4_hire, 8:31 PM 6/5/2003]
Team Owner
Joined: Feb 1999
Posts: 34,454
Likes: 665
From: Republic of Texas
Re: Demon Carb question (Guru_4_hire)
I'd say:
Vac Secondaries if you have a daily driver or concerned about gas mileage, and a Double Pumper if you are after total performace and/or if you engine make low vacuum.
Vac Secondaries if you have a daily driver or concerned about gas mileage, and a Double Pumper if you are after total performace and/or if you engine make low vacuum.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Demon Carb question (Corey 68)
I have not had a choke in 10-12 years and my vette always fires up even in below freezing weather. My right foot is my fast idle cuircut. It doesn't even need warming up to go.
IMO - starting right up is more of the state of motor tune and quality ignition parts. Not the choke.
IMO - starting right up is more of the state of motor tune and quality ignition parts. Not the choke.
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: Demon Carb question (Guru_4_hire)
A manual tranny doesn't "require" a mechanical secondary though mechanical secondaries are often more compatible with manuals than they are with autos. If jetting and everything else is the same, there should be no difference in fuel economy in normal driving between them. Keep in mind that the extra shot from the secondary accellerator pump, in the greater scheme of things, is a relatively small amount of fuel and it's only shot if you use the secondaries.
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 62,198
Likes: 1
From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Demon Carb question (Paul 75 L82)
Hmmmmmm I am hoping that it will help with alot of my engine trouble
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 62,198
Likes: 1
From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Demon Carb question (Jvette73)
I have no place I can rebuild it -- I think my first sergeant would flip out if I had my barracks room stinking like gasoline and a holley spread out all over my desk
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Demon Carb question (Jvette73)
So how have you come to the conclusion that the holley is crappin out? BTW, it can practically be rebuilt while its still on the car. As long as the throttle shaft bore arent worn out everything else is accesable on car. The fuel bowls come off, the metering plates, acess to jets and power valve, new gaskets, a few adjustments, not much else to it really.
Thread Starter
Team Owner
Joined: Apr 2002
Posts: 62,198
Likes: 1
From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Demon Carb question (Jvette73)
I think the accelerator pump and the power control valve are shot. It backfires alot, and we think its dumping in WAY too much fuel.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Demon Carb question (Guru_4_hire)
I think the accelerator pump and the power control valve are shot. It backfires alot, and we think its dumping in WAY too much fuel.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Demon Carb question (Jvette73)
http://www.mortec.com/carbs.htm great factory info for holleys here. it lists what was there when the carbs left the factory. That way you can change back if someone else f'd up. Yur list number for your carb is located on the front of the choke tower.
Former Vendor
Joined: Jan 2003
Posts: 20
Likes: 0
From: knoxville tn
Re: Demon Carb question (Guru_4_hire)
I have a Demon carb and love it. I have othing against a Holley and I have had reasonably good luck w/Holley carbs, but in my opinion, the Demon carb is better quality throughout.
The lighter the car and the lower the gear, the more a particular car lends itself to mechanical secondaries. I have used both on my '71 w/a 3.55 gear set and prefer the manual secondary route. Vacuum secondaries are more forgiving if you mismatch the carb to the car, but if you set it up right, you will get better performance from the mechanical carb.
Best of luck!
The lighter the car and the lower the gear, the more a particular car lends itself to mechanical secondaries. I have used both on my '71 w/a 3.55 gear set and prefer the manual secondary route. Vacuum secondaries are more forgiving if you mismatch the carb to the car, but if you set it up right, you will get better performance from the mechanical carb.
Best of luck!
