Re: advancing cam 4 degrees
Do you know if the cam is ground advanced or ?
If it is supposed to be advanced and you install it retarded it is going to run like, well, not so good.
We once accidentally installed a 30/30 cam in my Dad's 327 vette "straight up" and it felt horrible. No low end, fouled plugs, poor idle, pinging, gas mileage... Took it apart, added 4 degrees advance and bam! back to it's old self.
I've messed with adjustable timing gears on Toyotas too. I don't have any hard data to show you and I don't recommend randomly advancing cams without knowing what you are getting into, but advancing it 4 gave it better low end response. Felt lighter and snappier.
I don't know if the factory performance cams like L-79, 30/30 are ground advanced or got advanced by the specific timing chainsets, though. Somebody else may know.