how agrgressive a cam can I use with the 964 plastic manifold??
 

how agrgressive a cam can I use with the 964 plastic manifold?? I also have hydrlic rockers, so would an RS grind be ok on my 3.8?

Matt,

Not much,....:)

Those common-plenum, single-throttle intake systems don't like much duration or narrow lobe centers and are in fact, rather sensitive about this.

The factory RS grind is about max unless you are willing to live with a 1200 RPM idle and drivability issues below 2500 RPM.

I am no expert on cams... what is the definition of "ok?"

I think there are a bunch of variables to consider. Race or street? or mix? That may be the biggest consideration of all...

I run a plastic 993 intake with some extremely aggressive cams in my 3.8 liter racing engine. The cams I have are as aggressive as any being run in 8k rpm race motors with ITBs.

My engine was developed/built by an absolute expert, and in some places he says it makes as much or more power as his own 3.8 with ITBs.

My engine runs Haltech and an 80mm aftermarket throttle body.

Idle is about 1200, which is fine for my race engine.

I use the web cams supersport grind and back dated the rockers to non-hydraulic with '95 plastic intake and steve wong chipped motronic. send me an email and I'll send you the cam spec sheet and the dyno results.
My car weighs about 2250 full of fuel and oil, so I'm not so sensitive to low end.
274 rwhp and 275 rwtq were the peaks.

Doug