Degreeing the cam

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What are the effects when you advance cam timing. How do you know when its set properly. I understand the procedure but dont have any experience with the practical aplication.
Thanks
 
8) generally speaking when you advance the cam you gain low end torque and lose top end power, and when you retard the cam you gain top end power and lose low end torque. that said, there are combinations where you get the best of both worlds, and you can also lose in both areas as well.
 
I thought it was the other way around. Advancing gains upper end HP, but losses low end torque. I could be way off though. It's still early in the morning.

Slade
 
So what your doing is changing your opening degree? Then why dont the cam manufactures grind this into the cam? Or is this how you get the best of both worlds? Buy the cam and leave it alone or does degreeing tailor fit your cam to what your doing? And how do you know when enough adv or retard is enough.
 
The adjustability allows you to compensate for vagaries in timing gear manufacture, different track applications, personal preference on the part of the owner, etc.

As for how you know it's right: the proof is in where you place on race day. :D Or on a more pragmatic level, dyno testing will reveal all.
 
8) most cam grinders add a few degrees to allow for timing chain stretch. as for when to advance or retard the cam, at the race track when you have as much traction as you need then you advance the cam to get a better launch. if the track is slick then you retard the cam for a better top end charge.
 
So what your doing is changing your opening degree?

The greatest effect is on the intake valve CLOSING event. That is why retarding the cam gives more top end - it allows the intake valve to hang open longer, thereby allowing for more cylinder filling, improving hi end volumetric efficiency. Conversely, advancing the cam closes the intake earlier, trapping more of the charge as the piston is beginning its upward compression stroke.

Typically, advancing / retarding "rocks" the torque curve around its peak.
 
How does one effectively advance or retard the cam???
If the cam and crank marks are in the proper places and the cam needs to be moved?? Do you use offset keys in the cam or crank??
Is there an adjustable gear set for this??
Is there and adjustable gear set for the 4.9 litre Inline six (300 CID)??

I guess some of the newer cars use VVT or Variable Valve Timing.
The must be great benefit to this.........

ftwfred
 
Yup, like MIke's timing gears, they will have key ways for advancing and retarding.

THat is exactly why variable valve timing is so nice. It can run advanced at the low RPMs and retard at the high RPMs.

Gotta love modern technology.

Slade
 
Seperate keyways for advanced or retarded settings?
How far does it advance/retard the cam timing from stock??
I don't understand. :( :? :? :(
Where can they be purchased at?


Originally posted by CobraSix::
""Yup, like MIke's timing gears""
Who is "Mike"

ftwfred
 
I paid an extra 10-15 dollars and sent my single key timing gear back for what is called a nine keyway timing set. Its really for people like me who cant make up there mind what cam they want. It allows you to advance or retaird the cam duration by 4 degress for each key slot rather than replace the cam with a new one latter if you dont like it.
For example my cam is a 204 at 50 degree that peaks at about 4000rpm through to about 4500 rpm and by retairding it 4 degees it moves the usable rpm range up 200rpm 4200-4700rpm. You can keep retarding it until the lift becomes an issue probably about 8 to 12 degress would be my guess. Also increasing the cam LSA is not a bad idea if low rpm vacume becomes an issue. This is ground into the cam and cant be changed.
Im guessing that 200 rpm for every 4 degrees is propably is not accurate for an Aussie 250 especially when its pushing near 4800 with the standard rods etc. Needs a bit more duration than most. This is not necessarily bad as it allows you to retain good low rpm power and make decent power at higher rpm without reving too high.
 
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