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 Any feedback on STREET Demon carb?
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cortcomp
Coyote

USA
5335 Posts

Posted - 02 Feb 2014 :  5:26:25 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
http://www.demoncarbs.com/1903.asp

I was reading a magazine when i came across an ad for these. I know some of the demon carbs had a bad name from quality issues, but this is a new design and i found some points interesting:

  • No gaskets anywhere in fuel bowl area, both gaskets above and below fuel line
  • fits both a square and spreadbore intake manifold
  • HUGE secondaries, it's one big goggle-shaped secondaries
  • small primaries, for good throttle response and signal like a qjet
  • Small enough that you can fit 2 of them on small dual-quad oem manifolds


My qjet is 95% dialed in and these don't look OEM enough for me, but they look like an interesting carb. I wonder how they do on the street/strip, with those small primaries and huge secondary. They look simple enough also, no crazy linkages or anything, which might mean not that adjustable for how fast secondaries come in, etc.

Edited by - cortcomp on 02 Feb 2014 5:26:58 PM

Chicagogoat
Cochise

USA
823 Posts

Posted - 02 Feb 2014 :  8:38:58 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
It looks like another Carter rehash like Edelbrock. Carter are one of the most popular old school carbs especially with the Mopar crowd, they even came on 426 Hemi dual quads. The only thing I know about 'em is the AFB is a square bore like 4150 Holley's and the AVS was Carter's direct competitor to the Q-jet.

My opinion on Demon carbs have changed since the quality of late has been poor according to what I've read on the net and my own limited experience with a mighty demon 850. When I bought a speed demon 850 to replace my holley 750 vac sec carb for my newly built 455, milled 6X's, RPM int, XE284 motor over 10 years ago I was extremely happy and surprised how well these carbs worked out of the box. But in the spring of '12 I bought the before mentioned mighty demon carb to try out on my new hotter 455 combo and it was a real POS. I spent that entire season trying to tune out a part throttle to full throttle bog among other drivability issues. A year ago, with the advice from a Pontiac guy at a car show, I had a custom built holley type carb from Pro Systems that is simply awesome. Right out the gate it was better every way, crisp idle, great throttle response. Patrick, from Pro Systems, said there was a lot of inconsistency with the components on demons lately making them extremely unreliable and poor performers. I would think that their products have improved now that the company is owned by Holley.





Pure Pontiac: learn it, live it, love it!
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cortcomp
Coyote

USA
5335 Posts

Posted - 02 Feb 2014 :  10:22:28 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
It supposedly is a ground up design. It doesn't look like anything else that i'm aware of, even the carter remakes. (FWIW i know summit has their own brand holley knock off with some improvements.) If you look at the carb, it is a whole different setup from anything else i know. (someone else did a three barrel setup i guess but i don't know who that was?) Anyways, i guess it uses some holley parts for jets or something. The most impressive parts to me was: Goes on spread or square bore intake, and has tiny primaries and huge secondaries which drew me to the Qjet. Everything else is kind of just a bonus (no gaskets in the fuel level line, etc.) I wonder how tuning secondary opening rate, etc is. For $350, it's not a ton of money if you don't have a carb body to start with.
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Chicagogoat
Cochise

USA
823 Posts

Posted - 02 Feb 2014 :  11:28:10 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
I clicked on the pdf and you're right it's a ground up new design. It has a main body/fuel bowl in a single casting and can come with an optional composite polymer for weight and heat reduction! Also the secondaries have a unique "goggle" shape.

Pure Pontiac: learn it, live it, love it!
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 03 Feb 2014 :  05:13:52 AM  Show Profile  Reply with Quote
I've been watching out for a review too since it came to the market. Seems like it has the potential to be a great alternative to the crappy E carbs.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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cortcomp
Coyote

USA
5335 Posts

Posted - 03 Feb 2014 :  10:08:28 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Honestly might be a good alternative for guys who can't afford a custom Qjet and don't want to brave doing their own carb. It has the basic characteristics of one, some design improvements. Really it just comes down to how much you can tune those secondaries, and how much flow can you get out of them (can it feed a 468 at 6kRPM? the 750 seems like the largest currently?)

If anyone sees any pontiac dyno threads or articles or anything, post them here!

in if the mfr is reading this, send me one! I'll pay to have it dyno'd back to back against my Q-jet 462 so we have a decently rough estimate ;)
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Cliff R
Cochise

USA
535 Posts

Posted - 13 Feb 2014 :  07:53:04 AM  Show Profile  Visit Cliff R's Homepage  Reply with Quote
"I had a custom built holley type carb from Pro Systems that is simply awesome. Right out the gate it was better every way, crisp idle, great throttle response. Patrick, from Pro Systems, said there was a lot of inconsistency with the components on demons lately making them extremely unreliable and poor performers. I would think that their products have improved now that the company is owned by Holley."

It is true that the Demon carburetors have been plagued with issues from day one. The other problem with this deal is that it's a "hat trick" to buy any "shelf" carburetor and have it be spot on in all areas. A custom carburetor is built exactly for what you are doing. The shop building that carb users your engine/drivetrain/vehicle specs to supply a carburetor that's set-up for what you are doing.

The more experience the shop has with this sort of thing, the better the end result will be, at least from what I've seen since we went full time in this business over 10 years ago.

As the q-jet relates to this topic, if you have it dialed in exactly for what you are doing in all areas, NONE of these aftermarket carburetors will make one more ounce of power anyplace, or run quicker at the track. I found this out with my own Q-jet back when we tested the new (at that time) KRE heads. After all the testing was completed with my iron intake and q-jet, we bolted on a custom dyno tuned 4781-2 Holley 850 carburetor, to "see how much power the engine would really make", according to one of the participants witnessing the dyno runs that day. So we bolted on the big Holley, and on the very next pull the engine LOST 2hp!

Not being satisfied with that deal, we carried the same carb to the private track rental to test the new heads. On back to back runs swapping on the big Holley, the car lost .02 seconds and .30mph, just about what the dyno recorded for lost power....FWIW.....Cliff

If you can read this, thank a teacher. If you can read this in English, thank a Veteran.

Edited by - Cliff R on 14 Feb 2014 07:33:19 AM
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 13 Feb 2014 :  10:21:30 AM  Show Profile  Reply with Quote
Cliff, Cort is talking about this carb (not the Holley clone):


Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Paul
Cochise

USA
776 Posts

Posted - 13 Feb 2014 :  10:55:05 AM  Show Profile  Reply with Quote
It sure looks pretty, sounds like it has potential too
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cortcomp
Coyote

USA
5335 Posts

Posted - 13 Feb 2014 :  12:16:48 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Cliff, i would agree the custom carb way is the way to go, but many don't have the funds, or the desire, or even know that's an option. And to me, the holley design is a much updated version of a very simple design (4 big holes). I always felt the qjet was, while complicated in some aspects, setup to be able to handle all aspects of driving well instead of just idle and WOT.

I kind of like the ground up design of the street demon (not the holley clones but the one above), mainly the small primaries and huge secondaries like a qjet, but a smaller package and cheap enough to drop one on a project you're not obsessing over and being done. I have some friends that ask about carbs now and then and for the sbc, the cheap e-carb is where i usually send them if they don't have/want a qjet. This might be the carb i start sending people to, but i'd be curious if it has the secondary tuning potential and air flow for some of our bigger motors.
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 13 Feb 2014 :  8:06:40 PM  Show Profile  Reply with Quote
Just eyeballing it I have a sneaky suspicion that some factory air cleaner bases may have fitment issues. Especially drop bases.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Cliff R
Cochise

USA
535 Posts

Posted - 14 Feb 2014 :  07:45:49 AM  Show Profile  Visit Cliff R's Homepage  Reply with Quote
The Edelbrock Performer Series carburetors (AFB clones) are HOPELESS for what we are doing here. Not a day goes by that I don't have to listen to some poor soul who thought that the $200 Performer carb was the answer to all their issues, only to find out that they are big, ugly, and puke all over themselves when going quickly to full throttle on about 85-90 percent of the applications they get installed on.

I was in NAPA yesterday and my salesman asked me if I could tune one for his brand new pride and joy 355 SBC engine. SAME exact story I have to listen too 8-10 times a week. Idles nice, drives OK, but PUKES all over itself going quickly to full throttle. I suspect the 9 to 1 compression, 280 duration .480" lift cam, stock converter and 33" tall tires his pick-up uses has something to do with it? Folks don't realize until AFTER the purchase, that a carb with a weighted airflap just isn't going to cover 100 percent of all the applications it ends up on. From what I've seen with the AFB clones is that a really high hp/weight ratio car will hate them the most. Don't think I've ever worked on a vehicle using one that didn't have some sort of noticeable "kick" or transition when you opened the secondaries.

In any case, I've seen the new Demon street carbs. It looks like they took a Thermoquad and cross-bred it with an AVS. Quite unlikely I'll work with one anytime soon, and only know of one person who owns one. He actually likes it, after having to purchase as A/F metering and a bunch of tuning parts to get it dialed in for what he was doing......Cliff

If you can read this, thank a teacher. If you can read this in English, thank a Veteran.
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2horse
Tribal Scout

17 Posts

Posted - 02 Jun 2016 :  11:14:10 PM  Show Profile  Reply with Quote
Any newer info on these? Debating on getting one for 389. Have not read anything bad but no info on pontiacs. Thanks
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cortcomp
Coyote

USA
5335 Posts

Posted - 03 Jun 2016 :  09:50:38 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I'm curious too. I'm a very "must look stock" guy and so i haven't had a reason to run one. All of my current projects are done. I still wonder how these do, mainly if the secondaries are adjustable and the "bog" that the edelbrocks are known for are able to be tuned out.
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 03 Jun 2016 :  1:11:37 PM  Show Profile  Reply with Quote
The secondaries are supposed to be adjustable on these carbs unlike the Performer series E-carbs. Having also worked on some of those E-carbs, I have to say they are incredibly frustrating with the secondary issues. In some cases I found the carb worked almost flawlessly IF I removed the secondary linkage rod thereby disabling the secondaries entirely. This fixed another issue I experienced where the carbs can enter a weird dimension or "black hole" with moderate throttle (not enough to really get into the secondaries). Of course this is not a proper fix but made the cars normal to drive again including full throttle. These were smaller engines though (302-350's).

This Demon carb should compare more with the Thunder Series (AVS) E-carbs to be fair.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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2horse
Tribal Scout

17 Posts

Posted - 03 Jun 2016 :  10:47:24 PM  Show Profile  Reply with Quote
Will there be an issue with using a stock 66 389 intake with this carb?
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cortcomp
Coyote

USA
5335 Posts

Posted - 04 Jun 2016 :  7:07:08 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
It says square or spread bore, i'd imagine not?
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ponchopilot
Tribal Scout

USA
7 Posts

Posted - 30 Jul 2016 :  2:18:37 PM  Show Profile  Reply with Quote
I haven't got my Qjet rebuilt yet, so I put the 625 cfm model on my 350. So far it runs really great. Started right up and idled good, great throttle response. Had a pretty bad bog when dipping into the secondaries, but was easy enough to tune out by tightening the air valve spring up a bit. My 350 is very mild, so I'm not sure how well it would do on more high performance engines. But my personal experience has been very positive with this carb.

"95% of chevys are still on the road... the other 5% made it home."
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cortcomp
Coyote

USA
5335 Posts

Posted - 30 Jul 2016 :  4:33:49 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Glad to get feedback from an actual pontiac user. I like that they're compact, small primaries, and the fuel bowls bot having any gasket surface. If i ever did like a pontiac engine in a hotrod where bling counts, i think this would be a decent go-to.
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 30 Jul 2016 :  6:32:26 PM  Show Profile  Reply with Quote
Good info, thanks for sharing. And to add, within the past month a buddy put one on his boat (351W) after being urged by the engine builder who has been using these carbs exclusively. So far it's worked flawlessly. I'm still sticking with my Qjets but it's nice to have more options for the non-Qjet situations.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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ponchopilot
Tribal Scout

USA
7 Posts

Posted - 04 Aug 2016 :  10:08:36 PM  Show Profile  Reply with Quote
I thought I should add that I have a dual snorkel air cleaner off a '70 gto, and had no clearance issues. I've heard a lot of people have to use air cleaner spacers, when using after market open element air cleaners, but the factory one fit perfect.

"95% of chevys are still on the road... the other 5% made it home."
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cortcomp
Coyote

USA
5335 Posts

Posted - 05 Aug 2016 :  12:48:05 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I think this will be a good carb to recommend to friends when they won't hear about putting a qjet on their chrome engine.
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Phil
The Great White Buffalo

USA
7216 Posts

Posted - 05 Aug 2016 :  3:13:08 PM  Show Profile  Reply with Quote
That's good info about the stock 70 air cleaner fitting without issue.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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ThreeDeuce
Tribal Scout

USA
4 Posts

Posted - 30 Nov 2016 :  9:29:05 PM  Show Profile  Reply with Quote
Bought a Holley remanufactured #1905 750cfm off Ebay for $303.00. Putting it on a 428 I'm assembling, will write a review on it when I get it running. Plan on disassembling the carb just to check the two gaskets and make sure it's clean inside before install. They offer a composite fuel bowl on the other models; would like to see a comparison on same motor to see what the fuel temp difference makes in HP.
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