Cam advancement questions????

[LS6_Silverado]

Hey guys,

I changed out my cam today to my old stock ls6 cam after i got it back from specing. Just because i changed out my cam so many times and its easy for me i thought i would advance it just by moving the dot over by two gearteeth.

Well when i did the calculations i thought of the whole gear as 100 degrees of timing, and there are 44 teeth on the cam gear. So 100/44=2.27, 2.27 x 2 = 4.54 degees of advacment is what i thought i had....

But after going to math class i realized that a circle is 360 degrees so...
360 / 44 = 8.18
8.18 x 2 = 16.36 degrees of advacment!!!

Someone please tell me i didnt advance my truck 16 degrees!!!

Thanks, Brandon

[LS6_Silverado]

Come on someone has to know how many degrees the stock cam sprocket represents???
I just dont want to drive my truck if its advanced that much.

Brandon

[Madd Maxx]

The good news is you didn't advance your cam 16.36 degrees.
The bad news is you advanced it 32.72 degrees.

Every cam spec except LSA is measured in degrees of crank rotation. The crank rotates twice for every single rotation of the cam.

If you start your engine with the cam advanced that far, not only will it run like crap, but you may introduce your pistons to your valves.

[LS6_Silverado]

The good news is you didn't advance your cam 16.36 degrees.
The bad news is you advanced it 32.72 degrees.

Every cam spec except LSA is measured in degrees of crank rotation. The crank rotates twice for every single rotation of the cam.

If you start your engine with the cam advanced that far, not only will it run like crap, but you may introduce your pistons to your valves.

??? Explain more sorry i just dont understand. How many degrees does the stock cam gear represent?

[Madd Maxx]

In terms of camshaft phasing, the cam gear represents 720 degrees.

[LS6_Silverado]

That doesnt make sense because compcam double roller chains have 44 teeth and every gear tooth is 2 degrees retard/advanced. i just dont know if compcams change the amount of teeth on the crank gear compared to the stock one.

[Slimsilverado]

what was said earlier since the cam has to spin 360° 2 times for every 360° of crank rotation you double the cam degrees that why u have 32.72° in stead of 16.32° of advancement.... ouch

[LS6_Silverado]

so.... only two teeth on the cam gear will advance me 32 degrees???? and the compcam double roller will only advance me 2 degrees for every tooth?? This isnt making sense to me. And they both have 44 teeth on the cam gear.

I have driven the truck and it ride/starts up fine. But i do admit the down low is so hard it feels like i have vtec in my truck or something.

Doesnt the crank spin twice for everytime the cam spins once? Hince the bigger gear on cam?

This is turing out alot worse than i expected...

[LS6_Silverado]

I think i just figure it out

For every 360 degrees the crank rotates the cam rotates 180 degrees. So...

180/44 = 4.09
4.09 x 2 = 8.18 degrees of advanced

That number is much better than 32 degrees.

[Madd Maxx]

No. No. No.

OK, I'm going to try this again. The phasing of the camshaft (the amount of advance or retard) is measured in degrees of crank rotation. If a cam is advanced 6 degrees, for example, that means 6 degrees of crank rotation, which translates into 3 degrees of cam rotation. If you advanced your cam sprocket 16 degrees (two teeth), you have changed the cam phasing by 32 crank degrees. IOW, the cam is advanced 32 degrees.

Now is the time to stop driving your truck and fix the problem. We are trying to help you here. Please don't disregard this advice because you don't completely understand the mechanics of the issue. I apologize for being so blunt, but you can do some serious damage to the engine in its current condition.