ChevyFanatic

It seams that nearly every off the shelf cam comes with a ground-in 4 degrees of advance. Every single engine combintation that I have simulated on Desk-top-Dyno shows best power with 0 degrees of advance (about 20-40 hp better than with 4 degrees of advance). The dyno curves also show very very little low end loss at 0 degrees of advance.

So what gives? If Desk top dyno has any accuracy, why are all the cam manufactures recommending installing them 4 degrees advanced? Am I missing something here?

Jabroni

There's a certain compromise with advance and retard and the relationship to where the power will peak and so forth. You may get more power straight up but where does it peak at? 7K plus on most stock bottomed street engines just wont last long. You can get cams without advance or retard but something somewhere in the grind may balance the power curve so that you don't need 7500 RPM to peak.

ChevyFanatic

Thanks for the reply. Is it a matter of the idle getting bad with the cam timing retarded? My DTD runs showed better power from 4000 rpm on up, and only about a 7 hp loss at 2000 rpm. Any other Desk top dyno users out there that can confirm similar results when putting in a -4 for the advance (to achieve a net 0 degrees)?

wrencher

iTrader: (2)

The simple fact is that there is advance ground in to cam compensate for chain slack.
If you want to know how it is installed in your engine you have to degree the cam & confirm this.
Just slappin' the cam & chain on does not make it so.
I've seen some of 1 degree or more, my point , you have to check.
Most of the times when they are installed, it ends up being dead on.

Revelation222

A bit off the subject but where can you get this "Dest Top Dyno" program?

ChevyFanatic

http://www.motionsoftware.com/products.htm

Jorday

Yah, I hear that a cam has 4 deg advance ground it will be more like 2 when installed due to the slack in the stock timing chain.