Table of Contents
The first two numbers are the degrees of opening being 210 for the intake and 218 degrees for the exhaust given normally at .050 inch of lift. The next two numbers are the valve lift of intake and exhaust in thousands of an inch. The final number is the degrees of overlap.
How do you read a camshaft?
Reading a Cam Card: Lobe Separation Angle (LSA) This figure is derived by adding the intake center line plus the exhaust center line and dividing by two. In this case: 108 + 116 = 224 degrees / 2 = 112 degrees.
How do camshaft sizes work?
Typically camshaft manufacturers list this measurement by multiplying the cam lobe lift by the stock rocker arm ratio, usually 1.5:1. For example, if your cam lobe lift is . 319 and you’re using a 1.5:1 rocker arm ratio, you can take . 319 x 1.5, which is .
What is considered a big cam?
It is listed in degrees of crankshaft rotation. When someone refers to a “big cam,” they mean it has longer duration, not higher Lift. Duration at 0.050″ is the degrees of crankshaft rotation between when the lifter is raised 0.050″ and when it is 0.050″ from its resting position.
How do I find out my cam specs?
Take your digital caliper and measure the smallest diameter on the cam. This is called the base circle. This cam measured at 1.10 inches and 87 thousandths. The next value you will need is the largest diameter on the cam, the lobe part, which is called the base circle and lobe lift.
What’s more important lift or duration?
Designing a cam profile with more lift results in increased duration in the high-lift regions where cylinder heads flow the most air. Short duration cams with relatively high valve lift can provide excellent responsiveness, great torque, and good power. But high lift cams are less dependable.
What makes a cam aggressive?
In other words ‘intensity’ described how quickly the cam opened and closed from lower lift points to his standard lift point of 0.050”; the smaller the intensity, the more aggressive the opening and closing.
What makes a cam choppy?
LSA (lobe separation angle) determines the choppiness, it has to do with the overlap of when both valves are open, as in when the exhaust valve is closing and the intake valve is opening to pull fresh fuel in on the intake stroke after pushing out the burnt fuel. Most GM cams come on a 112, 114 or 116 LSA.
What is considered a mild cam?
An RV or towing camshaft, which is considered a mild performance or an economy cam, will often have a narrower LSA, between 112 and 114 degrees. Hot street camshafts usually have 110- to 112-degree LSA, while high performance and racing camshafts will often run between 105 and 108 degrees.
What is a Stage 1 cam?
Stage 1 cam sets are used to give increased Torque output in the RPM range below the engine’s Torque peak. More part-throttle Torque, better low RPM throttle response, and increased peak Torque will be produced by these cams. Peak horsepower may also be improved in some cases.
What does the lift on a cam mean?
LIFT: The cam’s basic function is to open the valves. Lift refers to how far the valve is opened (or lifted) off its seat. A street performance cam will usually have between .
How much HP does a cam add?
Does a camshaft increase horsepower? Yes, a camshaft adds 10 to 20 horsepower depending on the setup. To get the full potential of the high-performance camshaft, you’ll have to swap out additional components like the air intake, exhaust manifold, injectors, and valve heads.
What is rocker arm ratio?
The rocker arm ratio is the relationship between the 2 halves of the rocker arm. The halves are: The center of the valve stem to the center of the pivot point. (Dimension “Y” in the diagram.) The center of the pushrod to the center of the pivot point.
What does +4 mean on a cam?
Lsa is the spread between the intake and exhaust lobes which is ground into the cam. Its not adjustable. +4 or what ever amount you buy is the intake center line of the intake lobe degree. If you buy a cam with 112 + 0 then the intake center line is also 112.
What are the numbers on the back of a camshaft?
The first two numbers are the degrees of opening being 210 for the intake and 218 degrees for the exhaust given normally at . 050 inch of lift. The next two numbers are the valve lift of intake and exhaust in thousands of an inch. The final number is the degrees of overlap.
How do I identify a camshaft Comp cam?
COMP Cams uses two-number designations for all its engine families. The LS engine is designated 54 and this number is generally the first two numbers that define the actual cam part number. Other examples include small block Chevys -12, big block Chevys -11, and 5.0L small block Fords -35.
What is considered a lot of cam overlap?
To maintain sufficient idle and vacuum qualities, the cam tech recommends the cam be ground on, say, 112-degree LCA, which gives an overlap of 66 degrees. For a typical performance-headed 350, the optimal LCA is usually 108 degrees.
What does cam overlap do?
OVERLAP. Overlap is the angle in crankshaft degrees that both the intake and exhaust valves are open. This occurs at the end of the exhaust stroke and the beginning of the intake stroke. Increasing lift duration and/or decreasing lobe separation increases overlap.
Whats the difference in cam stages?
The Stage 1 and Stage 2 truck cams are designed to work well with the stock converter. The Stage 3 truck cam works well with a stock stall, but a 2,500 is recommended. The Stage 4 truck cam makes great power with a killer idle. It hits hard at 2,800-3,000 rpm –and keeps pulling through 6,800 rpm.
What does hotter cam mean?
The ZZ4 cam is a popular replacement for the GM Performance Parts hot cam as it has more lift and duration. Any cam that is bigger than stock is a “hot cam”.
How do you get a lopey idle?
For the low-buck street guy to get a lopey idle and see an increase in power without a drastic decrease in driveability, he needs a cam with a lobe-separation angle of 110 degreesthe same lobe lift as recommended earlierand duration numbers of about 218 degrees at . 050 inch lifter movement.
Does a cam change the sound?
More air and fuel, higher the pressure and it’s duration. Which creates more and a deeper sound. Cams have a very big say, in how well or little a engine breathes. So the change in note.
