Ford FE Engines by Barry Rabotnick

Author:Barry Rabotnick
Language: eng
Format: epub
ISBN: 9781613254820
Publisher: CarTech Inc.
Published: 2018-08-13T16:00:00+00:00

In comparison to the flat tappet cam shown earlier, this is a roller camshaft. Most roller camshafts will be made from steel. The machined finish visible between the lobes readily identifies them. Steel cams require the use of a compatible distributor gear.

So How Do I Pick a Cam?

The cam selection process can take a few different paths: You can open a catalog and find the one that most closely matches your desires based on the manufacturer’s information. You can call the cam company’s tech lines and get more detailed recommendations from the guys that answer such calls constantly. You can consult with your friends, engine builder, or machinist to benefit from their past experiences, or you can recruit a professional cam designer to create a cam profile matched to your specific needs.

None of these are wrong, but some methods are going to increase your chance of success. The engine builder, cam designer, and tech department are all likely to have considerable experience with the kind of questions that will arise. The designer will work from your combination to generate a profile, while the tech group will try to match a pre-existing catalog profile to your application. The cam designer will likely end up with the stronger combination, but that increment of power comes with a cost that is potentially too high for a more modest street build.

We’ll provide general guidance based on what has worked for us in various FE engine builds. As noted earlier, this is not to be taken as definitive but more as directional. Your results will certainly vary depending on the engine characteristics, including displacement and compression, along with car variables such as transmission, rear-end gearing, and your own perceptions and expectations regarding drivability, sound, and power.

Working with the common catalog cam profiles, we can make some very basic recommendations. These are dramatic simplifications, but provide a starting point. On a 390 engine keep the duration at .050 down to a range between 215 and 225 degrees for a mild idle, and 230 to 240 degrees for a choppy one. As you go up in displacement, you can go up a similar amount in duration and retain comparable driving and idle characteristics. A 10-percent or greater increase in displacement to a 445 can easily handle a cam with 235 degrees of duration at .050 lift with very good street manners. It’s something of a nonlinear sliding scale though, and even a 482-ci engine will want only around 250 degrees for a comparable performance range.

For lift we try to keep the milder street combinations at or below the .600-inch lift range. The reasons for this are twofold. First is that the Edelbrock heads we use are delivered with a spring and retainer package oriented around a .600-inch peak lift. Second is that keeping the lift within this window reduces likelihood for geometry issues or pushrod-to-intake interference.

One statement that holds true is that a larger-displacement engine can use a larger-duration cam with good results. Since most FE cam

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