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Old 09-05-2013, 11:29 PM   #1
iajonesy
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Default Demon Carbs......Good or Bad

I have a nice SBC engine for my 56 Chevy P/U project and it needs a carb. I had an Ebelbrock 600 cfm on it when it was dynoed and a buddy needed a carb real quick for his camper so I sold the E'brock to him. Now I'm ready to fire the engine again and have been thinking about a Street Demon 625 cfm with the composite float bowls. Does anyone have any experience with one of these carb? I watched a couple YouTube videos about them,but of course they were not going to bad mouth them (Chuck's Garage). Any help would be great.BTW,I have a new Holley 625 cfm carb on the shelf but I'm not the biggest fan of Holley carbs. Thanks.

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Old 09-05-2013, 11:58 PM   #2
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Default Re: Demon Carbs......Good or Bad

Are you considering another Edelbrock? I've had good luck with my Carter (essentially the same thing). Since this is a 600-625, I'm guessing all out performance is not a goal. I'm with you on the Holley.

What did the SB dyno at?
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Old 09-06-2013, 12:00 AM   #3
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Default Re: Demon Carbs......Good or Bad

I know I'm going to get flamed for this.....but the good ol' Rochester Q-Jet was a great little carb...when built right. Small primaries..gave you good response and gas mileage....and those large secondaries.....for when you wanted to show off in front of your friends.....

Low maint....reliable....

And....your in the ball park on your expectations on CFM....600-650...without a lot of bottom work....that is all a SBC needs....
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Old 09-06-2013, 12:24 AM   #4
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Default Re: Demon Carbs......Good or Bad

Quote:
Originally Posted by ddawg16 View Post
I know I'm going to get flamed for this.....but the good ol' Rochester Q-Jet was a great little carb...when built right. Small primaries..gave you good response and gas mileage....and those large secondaries.....for when you wanted to show off in front of your friends.....

Low maint....reliable....

And....your in the ball park on your expectations on CFM....600-650...without a lot of bottom work....that is all a SBC needs....
It's not like you told him to run a Carter Thermoquad.
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Old 09-06-2013, 12:37 AM   #5
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Default Re: Demon Carbs......Good or Bad

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Are you considering another Edelbrock? I've had good luck with my Carter (essentially the same thing). Since this is a 600-625, I'm guessing all out performance is not a goal. I'm with you on the Holley.

What did the SB dyno at?
It made 361 h.p. and 404 lbs.ft. of torque. It had large 1 3/4" primary headers on it. The dyno operator said 1 5/8" would yield more torque. We made 13 pulls and it gained a little more each pull. I was happy. Just want a nice reliable engine with enough power to be fun.

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Old 09-06-2013, 12:42 AM   #6
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Default Re: Demon Carbs......Good or Bad

The Street Demon is designed with small primaries like a Q-jet and the secondaries are like the old Holley 3 barrel carbs,with one butterfly. Demon calls this a Goggle Valve.It's supposed to give good mpg and quick throttle response and it's very easy to tune. The composite fuel bowl keeps the fuel 20 degrees cooler than intake temperatures.

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Old 09-06-2013, 04:46 AM   #7
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Default Re: Demon Carbs......Good or Bad

Quote:
Originally Posted by ddawg16 View Post
I know I'm going to get flamed for this.....but the good ol' Rochester Q-Jet was a great little carb...when built right. Small primaries..gave you good response and gas mileage....and those large secondaries.....for when you wanted to show off in front of your friends.....

Low maint....reliable....

And....your in the ball park on your expectations on CFM....600-650...without a lot of bottom work....that is all a SBC needs....
You won't get any argument from me on this, I agree completely. The trick is finding a good one these days or a decent rebuidable core.
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Old 09-06-2013, 05:03 AM   #8
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Default Re: Demon Carbs......Good or Bad





this one was killed by a demon sticking wide open. linkage issues out of the factory
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Old 09-06-2013, 06:29 AM   #9
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Default Re: Demon Carbs......Good or Bad

I had a Demon on my Monte Carlo, an early 750 Mighty Demon iirc. It was a step down from the King Demon whichever one that is. I have nothing but praise about it, never gave me an ounce of trouble, hit like a Holley, reliable like an Edelbrock, and as long as I stayed out of it got decent fuel mileage (11-12 mpg). I have heard other people had nothing but trouble out of them but I guess I was one of the lucky ones.
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Old 09-06-2013, 06:38 AM   #10
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Default Re: Demon Carbs......Good or Bad

Hey we ran thermo quads on all our bracket cars. Baddest carb ever built for a Chrysler the phenolic fuel bowl kept fuel cold and you could adjust that air door to perfection. That said on our cars that ran 6.90 and faster in the eight mile we ran Holley
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Old 09-06-2013, 06:39 AM   #11
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Default Re: Demon Carbs......Good or Bad

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Originally Posted by iajonesy View Post
it needs a carb.
I too will probably get flamed for this, but no it doesnt. Performance/car guys have been swapping over to fuel injection setups since they were first produced for SBCs ~56 years ago. Personally, Im a big fan of early Rochester mechanical injetions and the various vintage aftermarket setups, but even something more modern would both look good and perform more than adequately.
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Old 09-06-2013, 06:43 AM   #12
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Default Re: Demon Carbs......Good or Bad

Quote:
Originally Posted by ddawg16 View Post
I know I'm going to get flamed for this.....but the good ol' Rochester Q-Jet was a great little carb...when built right. Small primaries..gave you good response and gas mileage....and those large secondaries.....for when you wanted to show off in front of your friends.....

Low maint....reliable....

And....your in the ball park on your expectations on CFM....600-650...without a lot of bottom work....that is all a SBC needs....
John, for all the reasons you listed I would have to agree with you.

However, I understand the differences in preferences people have and many like and get relaible service from Edelbrocks, Holleys, etc. Many think a Rochester is complicated compared to an aftermarket but once you are in them, they are fairly straightforward to work on.
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Old 09-06-2013, 07:16 AM   #13
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Default Re: Demon Carbs......Good or Bad

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You won't get any argument from me on this, I agree completely. The trick is finding a good one these days or a decent rebuidable core.
Sean Murphy Induction did a great job with my E4ME (late electronic w/ electric choke). It was on an '85 Caprice w/90k miles and had never been touched until I sent it in...I knew it had choke problems and figured it was time to get checked out. New choke, TPS, and cleaned the crap out of it. It took a couple of weeks for the ECM to relearn things, but ran great after that.

If I were doing some sort of hotrod build I wouldn't hesitate to throw a Qjet on there.
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Old 09-06-2013, 08:35 AM   #14
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Default Re: Demon Carbs......Good or Bad

Well, Summit dropped them... returns. Barry Grant has shut his doors ? Never owned one considered it, are they good or bad, one thing I do know they were over priced, and now just another has been.
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Old 09-06-2013, 08:36 AM   #15
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Default Re: Demon Carbs......Good or Bad

I know at one time Jegs quit selling them because of people returning them and having problems with them. I'm not sure if they have started selling them again.
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Old 09-06-2013, 08:38 AM   #16
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Default Re: Demon Carbs......Good or Bad

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Well, Summit dropped them... returns. Barry Grant has shut his doors ? Never owned one considered it, are they good or bad, one thing I do know they were over priced, and now just another has been.
Now that's funny, You were typing about Summit and posted while I was typing about Jegs.
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Old 09-06-2013, 08:47 AM   #17
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Default Re: Demon Carbs......Good or Bad

I have a couple of friends with Demon carbs. I know one who had nothing but trouble, but it's in a lumpy cam situiation with low vacuum.
The others are on stock or mild applications with little to no issues.
Personally, I would use the Quadrajet if I could.
Superb carb in my opinion. I ran one, built by "The Carburator Shop" years ago, on the street on my '70 Stage 1 Buick.
The car was a street terror, Hemi Killer cam and loose converter.
It blew peoples minds when the QJ was noticed.
Enough of my babbling, consider a Q-jet.
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Old 09-06-2013, 09:04 AM   #18
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Default Re: Demon Carbs......Good or Bad

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Hey we ran thermo quads on all our bracket cars. Baddest carb ever built for a Chrysler the phenolic fuel bowl kept fuel cold and you could adjust that air door to perfection. That said on our cars that ran 6.90 and faster in the eight mile we ran Holley
I was only kidding about the ThermoQuad... They were so different and since they were pretty much a Mopar only carb, a lot of people didn't know how good they were. I used them on a couple of my Mopars. I got a lot of comments like you run that piece of crap carb?


The other thing is the Demon looks like a mutant Thermoquad.
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Old 09-06-2013, 09:12 AM   #19
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Default Re: Demon Carbs......Good or Bad

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Well, Summit dropped them... returns. Barry Grant has shut his doors ? Never owned one considered it, are they good or bad, one thing I do know they were over priced, and now just another has been.
BG went down a LONG time ago - 2-3 years?

Put another Ed on it. The Q-Jet comment gets no flame, I've seen them outrun a tuned Holley on the dyno. Holley makes a decent carb and they work well. Just go through one new before you stick it on the car. Eds are like mini-Qs - smaller primaries with efficient boosters and a mechanical secondary that is controlled by a weighed air vane. Great street and street/mild strip carbs. I'm going to play with two of those on a mild 302 - on a tunnel ram. That should be fun.

You'll hear a lot of "Holley will out run an Edelbrock" and it could be true. On the Mustang with the 302, we ran an Ed 600 for a while then switched to a Holley 600 DP. The Holley was about .1 and a couple MPH quicker in the 1/8 mile. Now - that was with a 4000 stall converter, 4.11 gears with a spool on drag slicks. If that's not your application, then comments like that from the carb internet peanut gallery don't apply.
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Old 09-06-2013, 10:08 AM   #20
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Default Re: Demon Carbs......Good or Bad

Quote:
Originally Posted by ddawg16 View Post
I know I'm going to get flamed for this.....but the good ol' Rochester Q-Jet was a great little carb...when built right. Small primaries..gave you good response and gas mileage....and those large secondaries.....for when you wanted to show off in front of your friends.....

Low maint....reliable....

And....your in the ball park on your expectations on CFM....600-650...without a lot of bottom work....that is all a SBC needs....
1987 El Camino 305c.i., E4ME quadra-jet (computer controlled)THM200C tranny, I get 24mpg regularly. Most other guys I know in this area same 5th gen elky with a edelbrock or holley only see about 15 if they are lucky. So i definately agree with you on the quadrajet. I love these carbs and would swear by them. So much so that when i build my "big" 350 I will find a nice non computer controlled Quadrajet and then stick a 200R4 behind the motor.

Besides, there is nothing like the Scream of a quadra-jet at full throttle
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Old 09-06-2013, 10:55 AM   #21
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Default Re: Demon Carbs......Good or Bad

you want a good carb go here.

http://www.blp.com/
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Old 09-06-2013, 11:05 AM   #22
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Default Re: Demon Carbs......Good or Bad

I heard Demons had terrible quality control problems. Things like metal shavings in the bowls brand new from the factory.

I'm not a Quadrajet fan unless it's something close to stock. I had one and had a local "guru" who's shop was supposed to be legendary for building them rebuild one for me and dial it in, and if I could have done it all over again, I would have gone in a different direction. Lots of issues, to the point where I almost just abandoned all the money I put into the carb and went with a new Edelbrock. I feel like the amount of people that really understand Quadrajets are few and far between.

If you were happy with an Edelbrock, I'd probably just replace it with that. If you're not a Holley fan, I would think any Demon carb would be even worse.
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Old 09-06-2013, 11:39 AM   #23
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Default Re: Demon Carbs......Good or Bad

One of the biggest issues with the Q-Jets....secondary jets leak (you have to epoxy them) and people omit the metal heat shield between the base and intake.
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Old 09-06-2013, 01:29 PM   #24
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Default Re: Demon Carbs......Good or Bad

i had a eddy 1406 600 cfm on my 350. I had that thing maxed out according to carb manual. My camaro ran good but it was to small for my combo. Only time I had an issue with the eddy was when junk got into the needle and seat. I finally wised up and put a fuel filter right before the carb inlets. If you go eddy, take it apart and check the floats. I hear many new ones the floats are not set probably and it will run like crap.

I ended up selling the 600 and put on 650dp Holley. My camaro runs so much better with the Holley once i got it tuned. My holley was a bit worn so I rebuilt it along with new accelerator pump, accelator pump arms, new floats etc. Once i dialed in the jetting and squirters, man it just takes off now.

If I had to buy a brand new carb though, I'd go with quickfuel.
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Old 09-06-2013, 01:41 PM   #25
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Default Re: Demon Carbs......Good or Bad

+1 on Holley carbs
I have a 750HP on a 377 long stroke, and the thing just screams.
Even though it does not have a choke, I still drove it just fine in ~40 degree weather.
I would highly recommend the HP series for a nice bolt on unit.
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Old 09-06-2013, 01:53 PM   #26
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Default Re: Demon Carbs......Good or Bad

What's wrong with a 600 Holley? I ran those for years w/o any troubles. The edelbrock carbs always gave me fits.
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Old 09-06-2013, 03:18 PM   #27
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Default Re: Demon Carbs......Good or Bad

Ive been using Holley carbs for years. Ive got a 750HP series on my motor right now. Theyve never been any trouble although one of my friends works with a guy thats had nothing but bad luck with them. They were the Street Avenger series.
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Old 09-06-2013, 06:01 PM   #28
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Default Re: Demon Carbs......Good or Bad

Same Company runs Quick Fuel , Holley and Demon now ,,after "bunkruptcy "
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Old 09-06-2013, 07:18 PM   #29
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Default Re: Demon Carbs......Good or Bad

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I heard Demons had terrible quality control problems. Things like metal shavings in the bowls brand new from the factory.

I'm not a Quadrajet fan unless it's something close to stock. I had one and had a local "guru" who's shop was supposed to be legendary for building them rebuild one for me and dial it in, and if I could have done it all over again, I would have gone in a different direction. Lots of issues, to the point where I almost just abandoned all the money I put into the carb and went with a new Edelbrock. I feel like the amount of people that really understand Quadrajets are few and far between.

If you were happy with an Edelbrock, I'd probably just replace it with that. If you're not a Holley fan, I would think any Demon carb would be even worse.


I totally agree, with everything you said. Ive been through the same with my Q-jet.
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Old 09-06-2013, 07:53 PM   #30
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Default Re: Demon Carbs......Good or Bad

non holley folks think turning out the idle mixture screws is adjusting the carb
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Old 09-06-2013, 08:27 PM   #31
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non holley folks think turning out the idle mixture screws is adjusting the carb
Carb snobbery?

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Old 09-06-2013, 11:29 PM   #32
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Default Re: Demon Carbs......Good or Bad

I have worked on a few Demon carbs. They looked nice, but the quality just was not there. Sealing surfaces were not flat, casting flash left over in passages, air bleed jet threads were pretty much non-existent, loose throttle shafts..........

Edelbrock's come with such jacked up jetting they almost will not run out of the box.

Off the shelf Holley's work but perform much better with a little work. Build quality is far superior to the Demon clones........
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Old 09-06-2013, 11:56 PM   #33
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1987 El Camino 305c.i., E4ME quadra-jet (computer controlled)THM200C tranny, I get 24mpg regularly. Most other guys I know in this area same 5th gen elky with a edelbrock or holley only see about 15 if they are lucky. So i definately agree with you on the quadrajet. I love these carbs and would swear by them. So much so that when i build my "big" 350 I will find a nice non computer controlled Quadrajet and then stick a 200R4 behind the motor.

Besides, there is nothing like the Scream of a quadra-jet at full throttle
Have to agree. Small primary's = good gas mileage. Larger secondary's for when you need the power. Great carb. There are plenty of them out ther pre 1981 for non computer control.
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Old 09-07-2013, 12:00 AM   #34
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Default Re: Demon Carbs......Good or Bad

My buddies went 9.10 with a Q jet ..SS/AA 1986 Camaro 454
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Old 09-07-2013, 08:02 AM   #35
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Default Re: Demon Carbs......Good or Bad

The thermoquad got a bad name too,called thermojunk.My father remembers them being junk and calls them thermojunks still.I seen an old Chrysler service slide on youtube,5 differant adjustsments and some of the adjustments required the carb removed from the vehicle.

http://www.youtube.com/watch?v=sv8ggASU1jE

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Old 09-07-2013, 09:52 AM   #36
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The thermoquad got a bad name too,called thermojunk.My father remembers them being junk and calls them thermojunks still.I seen an old Chrysler service slide on youtube,5 differant adjustsments and some of the adjustments required the carb removed from the vehicle.

http://www.youtube.com/watch?v=sv8ggASU1jE
That choke adjustment info brings back memories! I had a TQ on my 340 Duster. In my opinion, it was the most advanced production 4 Barrel carb made. Like any carb, there were issues. Some complaints of bowl warping. The plastic floats on some models took on fuel (common issue in the late 70's early 80's as fuel formulations changed). I remember buying used carbs to get the brass floats.

Unlike a lot of carbs, the throttle body was aluminum and seemed to hold up a lot better than the zinc castings (AFB was my other favorite). I had to deal with more than a few Quadrajets that had worn throttle shafts, I don't remember having the issue on the TQ.

Setting them up for a high over lap cam was not all the bad. Typically I ended up pulling the top off and opening up the idle feeds one size.

Like the Quadrajet, the large secondaries gave them a unique full throttle sound. Personally, I found them easier to work on the the Quadrajets.

The worst setup had to be the TQ on a Lean Burn 318. Early non computer units worked pretty well.

I would run one again on a street / strip car. I put one of the aftermarket TQ's on a 350 Chevy for a high school friend. He was very happy with the results. The hardest part is getting past people reaction to seeing "that" carb and the comments that follow.
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Old 09-07-2013, 01:05 PM   #37
crewchief888
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Default Re: Demon Carbs......Good or Bad

friend of mine had demon carbs on 2 of his engines.
both built SBC, one pushing approx 700hp in a mud bogger, it ran flawlessly

the other in a mild SBC powered jeep. it didnt run worth a damn at first, but after some fiddling with the accelerator pump, it wasnt too bad.

if i was gonna build a carbed engine for the street, i think i'd go with edelbrock, the ones i've played with seem to run pretty good right out of the box.

but,
with the availability of complete (relatively inexpensive) TBI systems, i wouldnt mess with a carb.


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