Which Ford Racing “303” Camshaft is Right for Your Fox Body Mustang?

If you are building up a Fox Body Mustang, chances are that you’ve heard of the Ford Racing cams (E303, B303, ETC.), commonly referred to as the “alphabet cams”. But, which cam is best for your application?

Before I tell you about the alphabet cams, you should know that these cams were all designed over 20 years ago, and designed for the masses. They are also known for poor quality control and are lacking in power output compared to modern aftermarket cams. Modern age technology has allowed companies like Anderson Motorsports to develop cams strictly using computers to figure out what performs and what doesn’t.

Ford Racing Cams

With that said, Alphabet cams are still good cams, especially if you’re on a budget.

E303 Camshaft

The E303 camshaft is the mildest of the Ford racing cams as you might be able to tell from the specifications. It’s known for its excellent street ability and decent track performance. I ran the E303 cam in my Fox Body for a very long time and loved it. It makes a ton of torque down low which makes it very street friendly, but it still makes decent top end power.

The E303 cam also has that lopey idle that we all know and love. If you plan on using your Fox Body for street use I would strongly recommend this camshaft.
Check latest E303 prices

B303 Camshaft

The B303 camshaft is a nice step up from the E303 cam. It’s still street friendly but moves the peak power up a little higher. I’ve helped build a couple Fox Body Mustangs with the B303 cam and it always surprises me. It’s not as street friendly as the E303, but it makes more peak horsepower. If you plan on using your Fox Body on the street and track I would definitely recommend the B303 cam.
Check latest B303 prices

F303 Camshaft

The F303 camshaft is loosely referred to as the “boost” cam. This is because it makes amazing power under boost, especially compared to the other “303” cams. We think it makes good power because it’s a happy medium between a high lift and long duration. The F303 cam is a decent naturally aspirated cam and some truck guys even love it, however, it performs best under boost. We don’t have any hands-on experience with the F303 cam, but if you plan on boosting your Fox Body this camshaft is for you.
Check latest F303 prices

X303 Camshaft

The X303 camshaft is basically a dedicated track cam. It has less duration than the F303 cam, but it has the most lift out of all the alphabet cams. This cam makes most of its power way up high and is not very street friendly. You may also need to use different pistons because the X303 has so much valve lift. This cam won’t perform all that well without a set of high flowing aluminum heads. I wouldn’t recommend running this cam unless your Fox Body is strictly a drag car and nothing else.
Check latest X303 prices

Z303 Camshaft

Last but certainly not least is the Z303 camshaft. This cam is a lot like the X303, but even more extreme. This came has a ridiculous .552 intake and exhaust lift. You will definitely need to notch your stock pistons or buy aftermarket pistons that can even clear that much lift. Obviously aftermarket heads are strongly recommended with this cam, otherwise, you’re just wasting your money. If you need the best drag racing cam possible then the Z303 cam is for you.
Check latest Z303 prices

Conclusion

The E303 is an awesome street cam, making power down low. The B303 is a good motorsports cam, making power in the middle. The F303 is an awesome cam for sub-600hp forced induction engines. The X303 and Z303 are a great drag strip cam, making lots of power up high. The reason all of these cams are popular is because they’re dirt cheap, ranging from $100-200, and make decent power especially when paired up with a set of high flowing aluminum cylinder heads.

However, I personally recommend spending the extra money and getting a modern camshaft that has a dual-plane lobe design. Or better yet, a custom made cam to match your driving needs and cylinder head flow.

About Bryce Cleveland 249 Articles

Bryce founded Dust Runners Automotive Journal in 2014 as a way to write about the cars he found interesting. When he’s not writing for Dust Runners he’s writing for Power Automedia as a freelancer. He currently drives a 2015 Fiesta ST and absolutely loves it.

1 Comment

  1. I have the B 303, late aluminum heads ported, # 6 boost, 1.72 rockers. Edelbrock intake, 70 mm TB, Mallory coil with John Deer copper ignition wire in a 88 LX SSP, J.B, headers, total after market suspension, flowmasters, 2 ” to the back. I have been racing since I was 14 and at 78 am still having fun, fun, fun ! Yes, I love the grudge matches at the drag strip !

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