Table of Contents
Reading a Cam Card: Duration & Advertised Duration This is defined as the number of degrees of crankshaft rotation that each valve that spends off the seat. All camshaft specs are expressed in degrees of crankshaft rotation. That means the crankshaft has to spin twice for the cam to turn one revolution.
What do the numbers mean on a cam shaft?
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.
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 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.
How do I know what size my cam is?
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 does a Stage 3 cam do?
The Stage 3 cam is designed to work with some larger valves, port work, and upgraded carburetor or EFI system. This cam starts moving the power band a little higher in the RPM range (2500-6000). This is the biggest cam we recommend for a street application. It is used commonly in the race and hot street applications.
What is considered an aggressive camshaft?
To measure how ‘aggressive’ a cam was, Harvey pioneered the idea of cam intensity. 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 is a good camshaft duration?
A 280-degree-duration cam holds the valves open longer than a 260-degree-duration cam. Holding the valves open longer allows more air and fuel into the engine and also allows more to get out through the exhaust. Longer duration (higher number) improves top-end power but almost always sacrifices low-end torque.
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 is a cam chart?
Content Addressable Memory (CAM) table is a system memory construct used by Ethernet switch logic which stores information such as MAC addresses available on physical ports with their associated VLAN Parameters.
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.
How do you read camshaft length?
How is it measured? Using a Dial Indicator and Degree Wheel, find the opening and closing points of the valves at 0.050 in. of lift. If the intake valve opens AFTER TDC, use a negative value. If the exhaust valve closes BEFORE TDC, use a negative value. Add the numbers together. Add 180° to find duration.
What determines cam rpm range?
How is it measured? The rpm range is determined by the camshaft manufacturer. The listed range is a result of testing the camshaft on a dyno with different combinations of engine parts.
Why do cammed cars lope?
the lope comes from what is effectively(in engine combustion terms) an overlap between one cylinder opening and another closing. These cams are designed to maximize the engine combustion cycle at very high RPMS with VERY large and Very Dense fuel air mixtures.
Should I advance my cam timing?
Not to be confused with ignition timing advance, advancing a camshaft will change the timing of the valve events in relation to where the crankshaft is positioned. Changing either affects engine performance, but a camshaft that is properly installed in an advanced position can noticeably improve performance.
What makes a cam lope at idle?
Therefore, a long-duration cam will cause rough running at idle (lope) and a loss of low-rpm torque.Know What The Numbers Mean, Then Make The Right Choice. EFFECTS OF LOBE SEPARATION ANGLE LSA: NARROW: WIDE: Intake close Earlier Later Exhaust open Later Earlier Exhaust close Later Earlier.
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.
How do I know what kind of cam My car has?
The stock cam will rock the car back and forth every once in a while when it’s hot out but, a car with an aftermarket cam will really get moving at times. If it sounds like and rocks like a 60’s muscle car.it probably has a cam.
What is and when does overlap happen with cam timing?
Overlap is when the intake and exhaust valves are open at the same time. It is expressed in degrees of crankshaft rotation. Not all camshafts have overlap. If they do, it happens at the end of the exhaust stroke and the beginning of the intake stroke.
