I still see people asking this very vague question in the communities. Truth is, no one can really answer that question. Sure there’s a “maximum” lift your stock 5.0 Fox can handle but that doesn’t mean it will be worth the effort.
The camshaft is like the mechanical brains of your 5.0 HO! I was going to go on a tangent about the ethics of a brain transplant but that’s a bit too “out there” but what I’m getting at is, before anyone can give you good advice they’d have to know more about your car, your engine and how you plan on using it. I recommend you speak to an engine builder or camshaft manufacturer for what would work best for your Mustang. A serious consultation is well worth your time and money.
A basic Understanding
The stock 5.0 HO cam in your foxbody Mustang (for the most part) is:
- Lift – .444 intake / .444 exhaust
- Duration @ 0.50 – 210 intake / 210 exhaust
- Lobe Separation Angle – 115 degrees
Bro, do You Even Lift?
Lift essentially means how much you can open the valves. More lift means you risk slapping pistons with valves and having to change your valve springs. Keep in mind that “more lift” does NOT automatically equate to more power! A stock piston 5.0 HO (85+) will accept maybe up to .520 lift with a maximum duration of around 220 at 0.50 with a lobe separation angle (LSA) of 114. Keep in mind that anything over .500 or less than 114 LSA you should measure clearances to be sure. Lifts beyond .480 will be critical on stock E7TE heads as the valve keeper might hit the guide seals (production variances). Upgraded springs will be an absolute necessity.
Because you can’t simply and quickly open/shut valves without an F1 type pneumatic valve actuation, our pushrod 302’s use a gradual slope to open the valves. The time it takes to open this valve is measured in degrees of duration. This will affect your torque curve and where it happens in the RPM range. Low duration opens the intake valve later and closes it sooner. Great for trucks as it gives higher torque at low RPMs, sacrificing higher RPM horsepower. High duration causes the intake valve to open early and close later. Moving your peak torque higher and increasing power.
Lobe Separation Angle (LSA)
“The lobe separation angle is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes,” says Eric Bolander of Erson Cams. “It affects the amount of valve overlap; that is the brief period of time when both the intake and exhaust valves are open.”
A smaller LSA (like 106 compared to the stock 115) will give that lumpy rough idle sound a lot of us look for or appreciate in exhaust tone. It will also increase maximum torque also moving it lower, more valve-overlap and decreases Piston-to-Valve clearance. A higher number, like the stock one, will reduce maximum torque but move it higher, softens the idle and improves overall drivability and increase Piston-to-Valve clearance.
Supercharged or nitrous engines should benefit from a wider lobe separation angle because they don’t need much overlap for exhaust scavenging. The opposite is true for a naturally aspirated engine. If you go from 115 to, let’s say, 106 on a stock 5.0L, you will get an awesome idle sound but it will pollute a lot more and you will probably have less power than if you stayed with the stock cam, or a more modest LSA.
Some Good Reading, If You Want to Learn More
A Cool Video Comparing a Lunati Cam to Stock
Keep in mind, this isn’t a purely stock 302!
Cam selection is more complicated than simply trying to fit the highest lift and most lumpy sounding one in your 5.oh! To do this right, unless you’re a skilled engine master, you have to ask around and be prepared by knowing what your goals are, how your car is setup and what was done to the engine.