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Discussion Starter #1 (Edited)
Example: Carb Spacer Dyno Test

by Camren Beattie

This '64 Falcon has a 9.5:1 302 with 289 heads, an E303 cam advanced 2 degrees, and a Typhoon manifold with an old Holley 600cfm vacuum secondary carburetor. It's backed by an AOD and 2800 stall. Since I was upgrading to a 680cfm Quick Fuel vacuum secondary carburetor, I figured I would also try a set of carb spacers and dyno before and after.I used the ProForm Trackside spacer kit which comes with three 1" spacers; open, four hole, and four hole tapered.

The car was dynoed at Adrenaline Autosports. With my old Holley 600 it baselined at 219 HP and 235 ft-lbs of torque.

With the Quick Fuel Super Street 680cfm bolted on it made 231 HP and 268 ft-lbs of torque, pretty much right out of the box with just setting the idle. Air-fuel was good at 13.7:1 across the board.

Then I tested the three spacers. They all were pretty close, and all higher than no spacer, but the open hole made the most power at 245HP and 277 ft-lbs of torque. The tapered was a few HP less, and the four-hole standard was lower in HP and torque.

Captions (From Left to Right)
1.The QFT 680cfm vacuum secondary carb with open hole spacer made 26HP and 24 ft-lbs of torque over my previous combo of an old 600cfm Holley and no spacer.

2.
'64 Ford Falcon Futura 2-Door Hard Top test vehicle. Under construction and driven to work.

3. My "before" combo: 600cfm Holley vacuum secondary on top of a Pro-Products Typhoon manifold.

4. The Quick Fuel Super Street 680cfm vacuum secondary. This thing is really crisp and made good power across the board.

5. The ProForm spacer kit. Pretty cool in that you can change out the 1" spacers really quickly without removing the carb studs.

6. Peak dyno sheet.
 

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Re: Example: Carb Spacer Dyno Test

Typhoon Manifold.... Does not ring a bell with me... is that a duel plane or single plane manifold?
 

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If you use an open hole spacer with a dual plane manifold, it is not more a dual plane.
It become a single plane, so it make more high end power...
 

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Re: Example: Carb Spacer Dyno Test

by Camren Beattie

This '64 Falcon has a 9.5:1 302 with 289 heads, an E303 cam advanced 2 degrees, and a Typhoon manifold with an old Holley 600cfm vacuum secondary carburetor. It's backed by an AOD and 2800 stall. Since I was upgrading to a 680cfm Quick Fuel vacuum secondary carburetor, I figured I would also try a set of carb spacers and dyno before and after.I used the ProForm Trackside spacer kit which comes with three 1" spacers; open, four hole, and four hole tapered.

The car was dynoed at . With my old Holley 600 it baselined at 219 HP and 235 ft-lbs of torque.

With the Quick Fuel Super Street 680cfm bolted on it made 231 HP and 268 ft-lbs of torque, pretty much right out of the box with just setting the idle. Air-fuel was good at 13.7:1 across the board.

Then I tested the three spacers. They all were pretty close, and all higher than no spacer, but the open hole made the most power at 245HP and 277 ft-lbs of torque. The tapered was a few HP less, and the four-hole standard was lower in HP and torque.

Captions (From Left to Right)
1.The QFT 680cfm vacuum secondary carb with open hole spacer made 26HP and 24 ft-lbs of torque over my previous combo of an old 600cfm Holley and no mr gasket carburetor spacer.

2.
'64 Ford Falcon Futura 2-Door Hard Top test vehicle. Under construction and driven to work.

3. My "before" combo: 600cfm Holley vacuum secondary on top of a Pro-Products Typhoon manifold.

4. The Quick Fuel Super Street 680cfm vacuum secondary. This thing is really crisp and made good power across the board.

5. The ProForm spacer kit. Pretty cool in that you can change out the 1" spacers really quickly without removing the carb studs.

6. Peak dyno sheet.
Can you recommend a good brand of carb spacer? 245 HP is quite a nice figure already.
 

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Re: Example: Carb Spacer Dyno Test

Did you try rejetting the main circut in the 600 CFM to see if the power went up or down. Holley's figures to 6000 RPM you are on the money with the 600 cfm.carb. Holley says you need 521 cfm of carb.

When you use a spacer of any size you make more volume in the induction area. If it's crisp check the plugs. Watch your not going lean.
 

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If you use an open hole spacer with a dual plane manifold, it is no more a dual plane.
It become a single plane, so it makes more high end power...
Nope, it just allows the engine to see both sides of the carb, like most newer dualplane intakes do.
Actually, the answer is between those two, but teyerdahl is on the right track. The purpose of a dual-plane (or 180°) intake is to isolate half of the cylinders to half of the carb to increase charge velocity, throttle response, carb signal, fuel atomization, and a few other good things. While adding a spacer defeats the purpose of the dual-plane and increases it's peak effective RPM range, it becomes a divided single-plane. This is not necessarily a bad thing, and this technique has been used for many, many years to take manifolds with insufficient top-end power, and sacrifice low-end response and torque (the dual-plane benefits) to get it. This is why some manufacturers do it with certain designs, to give a better peak HP capability. Note, however, that the factories don't allow nearly the crossover of a typical 1" carb spacer, and it's generally more of a 'notch' to save some of the dual-plane benefits.

I would caution, however, that spacers will always add power on a dyno. You can keep adding spacers and it will keep making more power - on a dyno. It is a popular technique when dyno racing, but often falls on it's face in the real-world. An example is using a thick open spacer on a dual-plane, where the loss of lower RPM torque can result in a slower car, even with the increase in peak HP.

Dyno numbers aside, final effectiveness can only be established on the track, and will more likely benefit drag racers (mostly high RPM) than street drivers (mostly low RPM). If it's a street car, the loss of response and torque will be noticeable, and overall effectiveness can only be judged on the street by the driver. This technique is a compromise, but fortunately, it's relatively cheap and easy to experiment with to see if it works for your setup.

David
 

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No not a problem at all...Just makes me wonder why people dig up threads that are several years old and the poster has undoubtedly solved the problem or more than likely is not even active here anymore. :confused:
 

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I would caution, however, that spacers will always add power on a dyno. You can keep adding spacers and it will keep making more power - on a dyno. It is a popular technique when dyno racing, but often falls on it's face in the real-world. An example is using a thick open spacer on a dual-plane, where the loss of lower RPM torque can result in a slower car, even with the increase in peak HP.

David
Just to dredge up a ridiculously old post again (currently reading while trapped in a boring meeting), the torque curve is so much more important than horsepower. I worked for one of the big 3 in their dyno labs, and of all the million and one things monitored, horsepower was usually not even monitored or talked about. The engineers talked almost exclusively about the torque curve at what rpm range.
 
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