Can someone please explain these specs on my camshaft?

MustangMatt1966

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Mar 11, 2004
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ok here they are: part number 31-246-3

valve adjustment: hyd

intake exhaust
gross valve lift: .520 .523
duration at.06 274 286

duration at .050 230 236
lobe lift .3250 .3270
lobe seperation 110.0

This is the cam in my car, but i had teh guy that built the engine choose, and the machanic i took my car to told me it was a big one.? can someone explain this stuff and tell me if this is a good cam or what not, im jsut trying to learn some stuff..thanks
Matt
 
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D.Hearne

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MustangMatt1966 said:
ok here they are: part number 31-246-3

valve adjustment: hyd

intake exhaust
gross valve lift: .520 .523
duration at.06 274 286

duration at .050 230 236
lobe lift .3250 .3270
lobe seperation 110.0

This is the cam in my car, but i had teh guy that built the engine choose, and the machanic i took my car to told me it was a big one.? can someone explain this stuff and tell me if this is a good cam or what not, im jsut trying to learn some stuff..thanks
Matt
That's a hydraulic cam, so the lifters don't need frequent adjustment.Gross valve lift is just that, both the intake & exhaust valves open up a little over 1/2 inch at maximum lift. Duration is the time the valves are open from the time they leave the seats to the time they close. The .050 duration figure is just another method to measure duration, it's the length of time the valve is open from .050 lift til it hits the .050 figure while closing. Lobe separation is the distance the intake and exhaust lobe peaks are separated. The lobe lift is the actual amount the lifter rises on the lobe, this amount times the rocker ratio gives you the gross lift.
 

sportsroof69

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Gross valve lift is how far the valve opens measured at the valve.

Duration at .06" (also called advertised duration) is the length of time the valve is open (duration) starting at .06" valve lift opening and ending at .06" closing (when airflow theoretically starts). The duration is actually degrees of crankshaft rotation.

Duration at .050" is the length of time the valve is open from .05" open to .05" closed. This is a more accurate representation of what the cam will be like. This duration is degrees of crankshaft rotation, too.

Lobe lift is the height of the cam lobe measured from the centerline of the cam. Multiply this number by the rocker arm ration to find out the valve lift.

Lobe seperation is a bit more complex to understand. LS is the distance between the centerline of each lobe measured in degrees of camshaft rotation. LSA affects the overlap which is the length of time that the exhaust and intake valve are open at the same time.

http://www.compcams.com/Technical/TimingTutorial/

Most other cam makers have similar tech articles.
 

D.Hearne

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sportsroof69 said:
Gross valve lift is how far the valve opens measured at the valve.

Duration at .06" (also called advertised duration) is the length of time the valve is open (duration) starting at .06" valve lift opening and ending at .06" closing (when airflow theoretically starts)
The .06 figure is a mistake, should be .006 :nice:
 

SnakeStang65

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One other small detail... The gross valve lift of .520 .523 is caluculated using 1.6:1 rocker arms. This means that the cam has a maximum lift of 0.325 and 0.3269.

This is useful information if you wanted to change to 1.7:1 rocker arms for a little more lift. 0.553 0.556.

I think you will find that the cam is great for your car. That cam will work excellent with a set of say AFR 165's, long tube headers of your choice, and a good dual plane intake with a 600 cfm carb.

John
 

FIRE14142002

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same cam I have in my 331. I could not run a 600 carb I had to go with a 750. the 600 just did not respond well at all but the 750 screamed. I know that i have 40 ci on you but it might be worth a try, and I know that even my motor called for only like 650 cfm but it would not turn the tires over. I've got a edelbrock 750 I need to get rid of. but it's a great cam. I've got @9.6 to 1 compression and have just a tad less than 400 hp.
 
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