Q-jet on a square bore Edelbrock manifold?

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anthonychacon80

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May 4, 2010
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Can this be done? I want the better mileage I am not getting with my Edelbrock 1406. Also I think having the ability to hook up my vapor lines again will help with the gas smell and further increase my mileage by returning unburned fuel instead of it evaporating into nowhere. Is this a wise set up? Further down the road I MAY use the Gm Performance spread bore Vortec manifold with EGR which having a Q-jet would also have the ability to use. But for now I want a carb that does not run like crap and that I can adjust using the directions in my 1980 Cutlass manual.

I found several adapters and I was wondering if these would work

http://www.jegs.com/i/Mr-Gasket/720/1932/10002/-1
720-1932.jpg

Mr. Gasket #720-1932
Any 4-bbl. carb to any 4-bbl.manifold except Holley 450 & OEM manifolds with exposed exhaust crossover tube, 3/4'' Thick
http://www.jegs.com/i/Edelbrock/350/2692/10002/-1
350-2692.jpg

Edelbrock 2692 - Edelbrock Carburetor Adapters Details
Mounts 4-bbl Rochester Quadrajet carburetors to square-bore, single-plane manifolds.



I have a PERFORMER EPS VORTEC 27164 (idle-5500 rpm)
Now available for small-block Chevys with Vortec or Edelbrock E-Tec cylinder heads, the Performer EPS dual-plane manifold is optimized to deliver superior performance with Edelbrock square-bore Performer Series or Thunder Series AVS carburetors. The runner design is "tuned" for peak torque around 3500 rpm on a 350-inch engine and it?s ideal for power from off- idle to 5500 rpm. Dyno tests showed gains averaging 5+ ft/lbs. of torque from 3000 to 4500 rpm for more performance where you need it most. Match with a dependable Edelbrock square-bore carburetor for maximum performance gains. Will not fit under stock Corvette hood.
 

JBreu

Royal Smart Person
Jul 15, 2008
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Livonia, New York
Yes that will work...I did that a long time ago with my '79 Monte that I had back in the day.............That's a cheaper way to go vs. a spreadbore intake 8)
 

anthonychacon80

Master Mechanic
May 4, 2010
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JBreu said:
Yes that will work...I did that a long time ago with my '79 Monte that I had back in the day.............That's a cheaper way to go vs. a spreadbore intake 8)


Which one of those adapters is best? The edelbrock says it is for single plane manifolds, what is a single plane? The manifold I have is a dual plane.
 

JBreu

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Jul 15, 2008
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Livonia, New York
Get the Mr.gasket adapter and you will be fine......A single plane intake manifold feeds all 8 cylinders from the same chamber, utilizing all 2 or 4 of the carb. venturis depending on engine demand. Mostly used in high performance applications.
A dual plane manifold has two chambers, each feeding 4 of the cylinders, splitting the use of the carb venturis. This makes for a better low throttle response, and a more streetable performance response.
Thats the technical difference between the two types.
 

anthonychacon80

Master Mechanic
May 4, 2010
303
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JBreu said:
Get the Mr.gasket adapter and you will be fine......A single plane intake manifold feeds all 8 cylinders from the same chamber, utilizing all 2 or 4 of the carb. venturis depending on engine demand. Mostly used in high performance applications.
A dual plane manifold has two chambers, each feeding 4 of the cylinders, splitting the use of the carb venturis. This makes for a better low throttle response, and a more streetable performance response.
Thats the technical difference between the two types.

so would using the spacer make it so the four ventruis are feeding both sides of the dual plane? Is that messing things up? Because now wouldnt there no longer be a devider between the two sides of the carb?
 

JBreu

Royal Smart Person
Jul 15, 2008
2,167
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Livonia, New York
JUst put the adapter on, drink a beer and call it a day..............You will be fine 8)
 

pontiacgp

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Mar 31, 2006
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I have a duel plane and the mr gasket adapter. They say the adapter costs some power but since it raised the carb that's gives it a bit of power so I look at it as a tradeoff. The car runs great and I get real decent fuel milage as long as my foot behaves... :twisted:
 

joe_padavano

Royal Smart Person
Sep 13, 2006
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The Qjet-to-square bore adapter disrupts flow and hurts power. You will negate at least part of the advantage of going to the aftermarket intake in the first place. The car will run if you can't afford a carb to match the intake, but I always wonder why people spend the money on an intake then negate it with one of these fugly adapters.
 

anthonychacon80

Master Mechanic
May 4, 2010
303
1
18
joe_padavano said:
The Qjet-to-square bore adapter disrupts flow and hurts power. You will negate at least part of the advantage of going to the aftermarket intake in the first place. The car will run if you can't afford a carb to match the intake, but I always wonder why people spend the money on an intake then negate it with one of these fugly adapters.


Well I am not trying to win any races or get a 12 second car. I want a good mix of power, but at the best mileage possible.

I also found this one...

http://www.jegs.com/i/JEGS/555/15440/10002/-1

555-15440_1.jpg

JEGS Carburetor Adapter Kit allows you to install a square flange carburetor onto a spread bore manifold. Precision machined to .750" from die cast aluminum. Includes gaskets and hardware. Can also be used to install a spread bore carburetor onto a square flange intake (requires 070-200-2413 Carb Stud Kit).
 

pontiacgp

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Mar 31, 2006
29,270
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Kitchener, Ontario
joe_padavano said:
The Qjet-to-square bore adapter disrupts flow and hurts power. You will negate at least part of the advantage of going to the aftermarket intake in the first place. The car will run if you can't afford a carb to match the intake, but I always wonder why people spend the money on an intake then negate it with one of these fugly adapters.

I don't have any dyno tests to show the difference but if the adapter does rob some power I sure can't notice it...if you have any numbers to show it disrupts the flow and hurts power I'd love to see them
 
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