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Keep the intake charge cooler while moving the power band higher
Edelbrock 7521 is a natural-aluminum RPM Air-Gap dual-plane intake manifold for Ford small-block 302-based engines and compatible 331-347 stroker combinations. Its open valley separates the runners from hot engine oil to support a denser charge in the verified 1,500-6,500 rpm range.
Key Features
- Air-Gap runner design separates the plenum and runners from hot engine-oil contact
- Dual-plane layout supports a broad street and strip torque curve
- Larger runner entries than the standard Performer RPM design benefit higher-displacement stroker combinations
- Natural cast-aluminum construction with square-bore carburetor flange
- Integrated nitrous bosses for a properly engineered installation
- No exhaust crossover and no provision for an exhaust-heated choke
Fitment
| Application Type | Verified Engine Requirements and Exclusions |
|---|---|
| Engine-specific | Ford small-block Windsor 302-based V8 and compatible 331-347 stroker combinations; high-performance 289/302-based engines only after complete port, head, deck-height, hood-clearance, carburetor, and accessory verification. Does not fit the 255 V8 and is not recommended for a typical 289 street build. |
Specifications
| Detail | Value |
|---|---|
| Manufacturer Part Number | 7521 |
| Series | Performer RPM Air-Gap |
| Engine Family | Ford small-block Windsor |
| Primary Engine Application | 302-based V8 and compatible 331-347 stroker combinations |
| Operating Range | 1,500-6,500 rpm |
| Design | Dual plane |
| Carburetor Flange | Square bore; one carburetor |
| Material | Aluminum |
| Finish | Natural |
| Carb Pad Height | 4.90 in |
| Front Height | 4.30 in |
| Rear Height | 5.50 in |
| Port Exit | 1.04 x 1.85 in |
| EGR | No |
| Exhaust Crossover | No |
| UPC | 085347075218 |
| Warranty | 12 months under current Edelbrock terms |
What's Included
- One natural-aluminum RPM Air-Gap intake manifold
- Only plugs or fittings supplied in the sealed manufacturer package
- Carburetor, intake gaskets, hardened-washer bolt kit, carburetor studs, RTV, linkage, and air cleaner are not included
About Edelbrock
Edelbrock develops intake manifolds, cylinder heads, carburetors, and supporting engine components around defined engine families and operating ranges. Its RPM Air-Gap designs apply competition-derived runner isolation to performance street and bracket-racing combinations.
Related Parts
- No internal carburetor, gasket, bolt, linkage, or air-cleaner product is linked because those parts must match the exact cylinder heads, transmission, carburetor choice, hood clearance, and engine combination.
FAQ
What is the 7521?It is a natural-aluminum, dual-plane RPM Air-Gap intake manifold for Ford small-block performance combinations in the verified operating range.
What engines is it intended for?It is intended primarily for 302-based Ford small-block engines and compatible 331-347 stroker combinations; a typical 289 application is not recommended.
Does it fit a Ford 255 V8?No. Edelbrock explicitly excludes the 255 V8.
What carburetor flange does it use?It uses a square-bore flange for one carburetor.
Are gaskets and bolts included?No. Select the correct intake gasket, hardened-washer bolt kit, carburetor studs, and RTV for the verified engine combination.
Does it have an exhaust crossover?No. It has no exhaust crossover and no provision for an exhaust-heated choke.
Will it work with an AOD transmission?Edelbrock carburetors can be used with a Ford AOD when the required compatible Lokar bracket and linkage components are installed and adjusted correctly.
What must be measured before installation?Verify head-port alignment, deck height, carburetor and air-cleaner height, distributor clearance, throttle linkage, accessories, fuel routing, and hood clearance.
Installation Instructions
- Confirm the Ford small-block engine family, displacement, cylinder heads, deck height, port dimensions, carburetor, transmission linkage, accessory layout, and hood clearance.
- Read the current Edelbrock instructions, disconnect the battery, drain the cooling system as required, and protect the engine from debris.
- Remove the carburetor and original intake components, label every connection, and clean the cylinder-head mating surfaces without allowing debris into the ports or lifter valley.
- Dry-fit the manifold to verify port alignment, distributor clearance, carburetor height, linkage travel, thermostat housing, and accessory compatibility.
- Install the recommended intake gaskets and RTV without using end-seal gaskets, then use hardened washers and torque the fasteners in Edelbrock's documented sequence and stages.
- Reconnect fuel, cooling, vacuum, throttle, and transmission-linkage systems, check for leaks and full linkage travel, set ignition and carburetor calibration, and recheck torque after the documented heat cycle.
California Proposition 65 Warning: This product can expose you to chemicals including antimony oxide and other chemicals known to the State of California to cause cancer or reproductive harm. For more information, visit www.P65Warnings.ca.gov.
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