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#1
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Does anyone have any experience with the new
Demon carbs? Is there any advantages over say a Holley 750 double pumper? What carb would you recommend for a 455 motor, bored over .060, ported Edelbrock heads, Performer RPM intake, 230/236 duration and 488/491 lift with 1.65 rockers. This motor is going in a 70 Gto body. Thanks for the help.
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77 Formula 8.47@ 158 70 GTO-11.37 @ 117.7 |
#2
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Does anyone have any experience with the new
Demon carbs? Is there any advantages over say a Holley 750 double pumper? What carb would you recommend for a 455 motor, bored over .060, ported Edelbrock heads, Performer RPM intake, 230/236 duration and 488/491 lift with 1.65 rockers. This motor is going in a 70 Gto body. Thanks for the help.
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77 Formula 8.47@ 158 70 GTO-11.37 @ 117.7 |
#3
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brin,
with your combination you will be far better off going with the tried and true Q-JET carb. they are cheap and plentiful, provide the best of both worlds(economy and performance) and if a rebuild kit is needed they are available from just about any auto parts store.
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Home of WFO Hyperformance Shaker induction. |
#4
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The Q jet is a good carb but to dial in takes alot longer than a Holley. I currently am still running one on an E headed roller 455.To tune the power circuit the top has to come off. To increase pump squirt have to drill out orifices. To richen idle circuit play with rod/jet difference or drill out orifices.
The acelerator pump circuitry is alot easier to tune on a Holley. Put on a different squirter or a different cam. Usually the idle circuits are better for a performance engine. A Texas Pontiac racer Mike Cook had a similar combo and ran an 800 Holley DP running 12 teens in the 95 degree weather with a 3.31 gear!. Skip Fix
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#5
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What is the intended use of the car? Street, strip, or a little of both.
What Skip says about a Holley is true for a race car, and all out performance!! For street/strip, or just street, you can't beat the Q-jet. The Holley will never come close to the mileage figures of a Q-jet, and the Q-jet can be made to perform quite well, with very few extras. |
#6
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I don't have personal experience with the Demon - but talked to several who has. Both the new Holley and the Demon are better then the older Holleys in that the tolerances and quality control have improved. These two companies are at each others throats so marketing is the main difference. Holley has been around since the 1800's (started out in PA) Barry Grant(demon) jumped aboard the carb market and has been quite successful. The older Holleys sometimes(mostly) needed "blueprinting" and that caused many performance carb "builders" to emerge. I personally like the Holleys - I buy them used reasonably and love to play with them - they are very simple. The q-jet is a great carb as well but harder to tune Your motor(in my opinion) needs at least 800 CFM to take advantage of the flow from the E-heads. Pontiac carbs are 750 CFM - Some Ram Air(read rare/expensive)carbs flow 780CFM. The 455HO and 70-71 Buick 455's are 800 CFM. When building a fast street Pontiac - I throw away gas mileage and go for as fast as possible. So I would run a 800-850 Demon(prettier) or Holley and a 1"-2"(clearance problem) carb spacer as well. I know Jim Hand will not agree - but I am a single plain intake fan (torkerII - Holley street Dominator - Warrior)But the performer and Rpm have a nice plenem. I usually like to match the carb with the plenem so the performer and RPM (and stock cast iron) match nicely to the Q-jet. Since I like Holleys - they match better to the single plains listed. If you can find a 800 CFM Q-jet - it will do well. By the way - Pontiac ran the 800 CFM carb with 8.4 compression 068 cam (.406 lift)
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~~~~~~~~~~~~~~~~~~~~~~~~~ www.spottsperformance.com East Coast Pontiac engine builder - still going strong 4 month waiting list email spotfam@verizon.net 1981 Trans Am 455 w/6X heads 4 speed 4 wheel disc (for sale) 1969 Trans Am clone 9.79 at 139 so far 1964 Banshee clone project - Opel GT platform |
#7
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Well I think the Edelbrock carbs are better than holley and qjet. I just bought one and my TA runs great. Only problem I had is with the electric choke clearance, but I worked around that. I am satisfied.
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#8
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I think most 11.00 sec. and above cars will run fine with a properly turned Q-Jet. You must have a good electric fuel pump. I plan to run a 10 sec pass this season with a Q-jet.
------------------ Bobtempest Going fast with class! '67 Tempest @ 11.26 at 3850lbs with air & Q-Jet March 98 Car Craft
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Bob |
#9
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I for years I was die hard Q-jet fan, but the reality is there a great street carb, but a nightmare to tune, if you want to go fast, that's were the Holley takes over in my opinion. The Q-jet is no compition for an out of the box Holley with some jets changes, and right size squriters. The Holley's
with the four corner idlers are the best and easiest carb in the world to tune with.
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#10
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Have you looked into the 'new' Federal Mogul/Carter Competition Series carbs? I think they run anywhere from 500cfm on up to 750cfm. They also offer a strip kit with about every possible metering rod and jet combo you might want to try. Real EZ to tune. My $.02...
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