Camshaft lobe separation angle: what does it mean?

Camshaft lobe separation angle: what does it mean?

By Freddie Heaney:

The lobe separation angle of a camshaft is typically determined by the engine’s purpose, its displacement and its compression ratio.

A 350cu in oval track racing engine, for example, often runs on a narrow lobe separation angle of 106 degrees. In contrast, a smooth-running high-performance street engine might use a lobe separation angle of 112 to 114 degrees. Five-hundred cubic inch NHRA Pro Stock engines that rev to 11,000rpm operate on 116 degrees and 800-plus cu in Pro Stock Mountain Motors 120 to 122.

The lobe separation angle or LSA is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes.

The lobe separation angle or LSA is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes.

The lobe separation angle or LSA is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes. It affects the amount of valve overlap; that is the brief period of time when both the intake and exhaust valves are open.

A narrower LSA adopts more overlap and with it a lumpier idle and a narrower more specific power band. The narrower separation makes the engine sound choppier. Some engine specialists refer to it as that 106 sound—the NASCAR and short track oval sound where preferred lobe separation is usually specified between 104 and 106 degrees. The primary function of narrow lobe separation is to impel urgent acceleration off the turns when the throttle is opened.

A wider LSA, on the other hand, reduces valve overlap, offering better idle and cruising qualities. Supercharged engines typically benefit from a wider LSA because they don’t require as much overlap for exhaust scavenging as does the naturally aspirated engine.

Doug Patton, Pro Line Racing Engines

Doug Patton, Pro Line Racing Engines

“Changing the lobe separation angle,” says Doug Patton of Pro Line Race Engines, “changes the amount of overlap that exists during the time the intake and exhaust valves are both open. On a naturally aspirated engine, the lobe separation angle has an effect on whether the engine reaches peak torque a little earlier or later in the rpm range. Typically, narrower lobe separation develops peak torque at lower rpm and widening the separation tends to build peak torque higher in the rpm range. Nitrous engines, which make plenty of power and torque, often run wide lobe separation angles to moderate cylinder pressures and temperatures.

“Lobe separation angles,” he continues, “are influenced by the camshaft grind. If a street car has smaller lift (the amount the valve lifts off its seat) and duration numbers (the degrees of crankshaft rotation for which the valve is held open) they might run 112 or 114. Widening their separation angle helps increase upper rpm power output. Alternatively, if you are running a bigger camshaft to gain maximum top-end power, cam makers often suggest reducing the lobe separation angle to recover power lost in the lower rev range.”

Chuck Lawrence, Jon Kaase Racing Engines

Chuck Lawrence, Jon Kaase Racing Engines

Tellingly, when engine builder Chuck Lawrence received the order to bestow a 520cu in big-block Ford with the sound of a Pro Stock engine, he replaced the normal 112LSA hydraulic roller cam with one of 108LSA. “The result sounded wonderful,” said Lawrence, “but it didn’t rev as enthusiastically and it made 30hp less than normal!”

“If you changed the lobe separation of a street engine from 112 degrees to 106 and didn’t do anything else,” says Jon Kaase, “the engine would idle a lot rougher and generate worse exhaust emissions largely because of unburned fuel.”

In conclusion, lobe separation angles change the amount of valve overlap, which affects many performance factors particularly idle quality, peak torque that can be moved from a lower rev range to a higher range and power bands that can be narrowed or broadened.

Narrow Angle (104 degrees)

  • Lower rpm torque range
  • Increases maximum torque
  • Higher cylinder pressure
  • Lower idle vacuum
  • Rough idle quality
  • Valve overlap increases

Wide Angle (115 degrees)

  • Higher rpm torque range
  • Decreases max torque
  • Lower cylinder pressure
  • Higher idle vacuum
  • Smooth idle quality
  • Valve overlap decreases


John Hartman (

Erson Cams


  1. I have taken a look at this topic on LSA and I want to know more and hope to benefit from you

    • I have a Howard’s small base circle hyd roller camshaft. I understand all the numbers except the L/C. It is 110+4. What exactly does that mean. Your input would be greatly appreciated. Thanks in advance, Randy Graves

  2. Thank you for your note. Could you tell us more specifically the information you’d like to receive. Failing this, please contact John Hartman by email:

  3. My problem is raw fuel going off like a bomb on deceleration.

    This occurs on my recently built 496 BBC stroker. It has big port raised-exhaust port heads and squared, 0.005 in the hole with Wiesco +0.020 dome pistons. The static compression ratio seems to be around 11:1. It produces 180 psi when closing all cylinders. It has 7 inches of vacuum with a Lunati hydraulic roller cam that lifts 0.629-629 with duration of 250 in, 255 ex., 110 centerline and 112 LSA.

    Originally, on startup I ran gasoline 93 and a Barry Grant 850cfm with no problem but the carb was noticeably small for this engine. So, I decided to go E-85 with a new 950 Holley E-85 carb, which is when trouble struck. Assuming it was a jetting issue, I spent much time with Holley “techs”. But after tuning this carb from a-z there was no change and I’ve come to the conclusion it is not a carb issue. The car pulls hard to 7000rpm but whether coming off full throttle or just granny shifting, I get this back-blast in the headers. Do you think it could be scavenging or cam timing or wrong cam? I’ve replaced the wires, 6AL box, and re-degreed the cam. I’d be grateful for your help. Thank you, Tom Muzik

  4. A lot of street racers like to fit a big cam in their engines because it sounds good even in a stock engine like a 68-70 327cid Chevrolet, which has 275-300hp. However, without changing anything else, you’ll lose horsepower – vacuum secondaries won’t open, too much overlap in 108 LSA or below. If you don’t go all the way – Compression ratio, larger valves in heads, headers, high-rise alum, mechanical secondaries Holley carb, balanced engine, 3in exhaust etc. – don’t start, for it will be a waste of money.


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