Tech Articles

Ford Alphabet Cam Specs: E303 vs. B303 vs. F303 vs. X303

 
E303-Camshaft-Installation

(Image/MustangandFords.com)

Ford’s famous Alphabet Cams (a.k.a. Letter Cams) have been around for decades and are often the go-to choice for Mustang owners looking for more performance from their 5.0L engine.

Ford Performance designed these cams for the 1985-and-up 5.0L/302 roller cam engines with 1.6 ratio rockers. On engines running electronic fuel injection (EFI), these camshafts are only compatible with mass air induction systems.

We’re going to look at four different cams from the “alpha” cam family: E303, B303, F303, and X303.

You can think of each cam as a performance tier, starting with mild street performance and ending with track use.

Here’s a quick overview of each cam’s basic qualities, and you can get the full spec breakout in the table below.

Ford Alphabet Cam Characteristics

E303

The E303 adds mild performance improvements across the rpm range.

B303

The B303 takes the performance up a notch without losing much streetability.

F303

This cam makes power up to 6,200 rpm and is a good complement to forced induction (e.g. supercharging). You may have to modify your pistons for proper piston-to-valve clearance. (Recommended for manual transmissions.)

X303

You’ll gain torque and power up to 6,500 rpm. Like the F303 cam note above, you should check valve clearance and modify your pistons accordingly.

Ford Alphabet Cam Specs

CamshaftBasic Operating Range (rpm)Intake Duration at .050" LiftExhaust Duration at .050" liftIntake Duration (Advertised)Exhaust Duration (Advertised)Intake Valve LiftExhaust Valve LiftLobe Separation
E3032,500-5,5002202202822820.498"0.498"110°
B3033,000-6,0002242242842840.480"0.480"112°
F3033,500-6,5002262262882880.512"0.512"114°
X3032,200-6,2002242242862860.542"0.542"112°

 

For more specs, check out this data sheet from Ford Performance.

 

Additional Upgrades

These camshafts require new valve springs. Ford Performance says you’ll need springs rated at a minimum pressure of 120 lbs. (closed) and 295 lbs. (open).

For automatic transmission applications, Ford Performance recommends a torque converter with higher stall rating than stock when using these camshafts.

Tags: , , ,

Leave a Reply

Your email address will not be published. Required fields are marked *

*

This site uses Akismet to reduce spam. Learn how your comment data is processed.