Holley Medium Riser Aluminum Intake Manifold

Let’s discover the purpose of an intake manifold.

Application: Ford FE 427 Side Oiler

What is an intake manifold used for?

The intake manifold is a key engine component:

it channels the air/fuel mixture (or air alone in fuel-injected systems) from the carburetor to the cylinder heads, and then to each cylinder.

Its role is threefold:

▪ Distribute the mixture evenly to all 8 cylinders

▪ Optimize the speed and volume of airflow

▪ Define the engine’s effective operating range (torque / power)

On a 427 FE Side Oiler—an engine originally designed for racing (NASCAR, Le Mans, drag racing)—the intake manifold plays an even more critical role:

➡️ it largely defines the engine’s character, far more than on a modern small-block engine.

What is a Medium Riser intake manifold?

On Ford FE engines (352 to 427), there are historically several intake heights and port cross-sections, known as Risers.

The main FE families:

👉 The Medium Riser is the best performance / drivability compromise for a sporty street-driven 427.

The Holley Medium Riser aluminum intake manifold

General characteristics

• Designed for FE Medium Riser cylinder heads

• Aluminum: lighter weight, better heat dissipation

• Compatible with Holley 4-barrel carburetors (4150 / 4160)

• Single-plane or dual-plane architecture depending on the version (often single-plane in performance-oriented Medium Riser setups)

Advantages of aluminum:

• Significant weight savings compared to cast iron

• Lower intake temperatures → denser air/fuel mixture

• Improved engine responsiveness

• Better compatibility with modern carburetors

On a 427 FE, aluminum is perfectly consistent with:

• forged pistons

• Edelbrock cylinder heads

• a moderately aggressive performance camshaft

• Holley 750 cfm carburetion

Size, volume, and geometry: why they change everything

Runner cross-section

• Small cross-section → high air velocity → strong low-end torque

• Large cross-section → maximum airflow → high-rpm power

The Medium Riser sits exactly between the two:

• large enough to feed a 427 up to 6,500 rpm

• not too large, preserving usable torque from as low as 3,000 rpm

👉 Ideal for your CRANE CAMS 238/248 camshaft, with a 3,000–6,500 RPM operating range.

Intake height

• The taller the manifold, the straighter the runners

• Straighter runners = better high-rpm cylinder filling

• BUT: harder to exploit at low rpm

The Medium Riser:

✔️ improves airflow

✔️ without sacrificing low- and mid-range torque

✔️ remains compatible with a low-profile Cobra ERA hood

Single-plane vs Dual-plane (case of the 427)

Dual-plane

• Two separate intake circuits

• Very strong low-end torque

• Limited high-rpm performance

Single-plane (most common in Medium Riser setups)

• All cylinders share the same plenum volume

• More uniform airflow at high rpm

• Less torque below 2,500 rpm

➡️ On a 427 Side Oiler, the single-plane Medium Riser is the right choice:

• the engine is naturally very torquey

• intended for sporty driving

• more aggressive exhaust note

• sharper revving behavior

Compatibility with the 427 Side Oiler setup

Your engine:

• 427 FE Side Oiler

• Edelbrock aluminum cylinder heads

• Holley 750 cfm double-pumper

• 1/2” phenolic spacer

• XE 274H camshaft – 1,800 / 6,000 RPM

➡️ The Holley Medium Riser intake manifold is perfectly sized:

• The plenum volume matches the airflow of a 750 cfm carburetor

• The spacer improves thermal isolation and carburetor signal

• No airflow restriction at high rpm

• Torque remains strong thanks to the massive displacement

Consequences of choosing a different option

Low Riser

❌ Engine feels choked above 5,500 rpm

❌ “Restricted” driving sensation

✔️ Very strong low-end torque (unnecessary on a 427)

High Riser

❌ Significant flat spot below 3,000 rpm

❌ Difficult to tune for street use

❌ Hood clearance often an issue

✔️ Only truly effective above 6,500 rpm

The Medium Riser is the smart choice, not the extreme one.

Conclusion

The Holley Medium Riser aluminum intake manifold is:

• historically consistent with the 427 FE

• mechanically perfectly matched to your camshaft

• ideal for a high-performance, usable, and reliable Cobra ERA

• capable of delivering massive torque plus real top-end pull

👉 This is exactly the intake manifold used on a well-built 427 Side Oiler “street/track” engine—not a show engine, and not a pure drag setup.