Cam Question for 03 Cobra

Looking at doing cams on my car, And was wanting a pretty lopey cam, But I know these days it's hard to do so without jeopardizing HP/TQ .
What's y'alls experiences with a selection and loss, or gain?
My car currently has a a few mods.
Built motor
Ported heads
2.76 pulley
CAI
KB BAP
Catback with off-road procharger.

My future goals will be a 2.9 Whipple, or VMP.

Having been down this road and through a couple sets of cams and multiple re-degreeing of my cams adjusting them I'll toss in my 2 cents.

Lopey idle sounds cool and that's where it ends. It drives like crap, it bleeds off boost in power, has reversion and higher IAT2s.
To define "drives like crap". Pulling off the car can be touchy. Ride the clutch out some. If the clutch grabs to soon it'll buck, hesitate and even back fire if real bad. You can spend some time in the tune playing with fueling and timing and smooth a lot out but you can't fix beyond the mechanical limitations of what the cams are doing.
To further compound the problem on our cars we have a boost bypass valve which as I've found needs at least 11" of vacuum or so to operate. Lopey cams with a "cool" idle have about 6 ~ 8" of vacuum at idle. That means your bypass valve is partially open or fluttering. This really aggravates the drivability issues as the bypass valve flaps in out and out of boost mode when trying to pull off or even part throttle driving. Heck even cruising down the highway at 70 mph and very lightly moving the gas pedal when you hit that sweet spot you'll see your vacuum/boost gauge fluttering along with your wideband and the jerkyness of the car can be felt by you and passengers. Mildly but you can feel it.
Your idle will be real sensitive too. Turn the a/c on and it may even stall. Again lots of adjustments in the tune to compensate but only so much can be done.

A low spring pressure bypass valve is a bandaid and has its own issues. It's operating at almost 0 vacuum and the rotors of the blower are filled with air when it activates so the car still jerks and shakes with the spike of "boost" as it operates. It's a bit better than stock but still sucks and is annoying.

Put a tiny bit of negative overlap in your cams. Doesn't take much, -8 to -10 degrees or so and it'll drive practically like stock. You'll have about 14" of vacuum at idle which is just enough to hold the bypass valve in place even when the engine loads up as the clutch is coming out and you're pulling off. The car will be 100 million times better to drive. You won't bleed off boost when in it hard either. It's a win win. You won't have the crazy lopey or choppy sounding idle but you can still hear the car has cams.

Or get the lopey idle that sounds cool and just live with the other stuff lol.

Interesting though, I appreciate the info.
I hear the 96-98 Cobra cams do good in our cars, Any truth to that

The 96-98 intake cams have a few more degrees duration than stock so yes that's a small improvement. Exhaust cams are identical so don't bother swapping that one out.

MalcolmV8 said:

Exhaust cams are identical so don't bother swapping that one out.

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He'd pick up the larger 12mm cam gear bolt though.

cj428mach said:

He'd pick up the larger 12mm cam gear bolt though.

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Unless you're running aftermarket springs with lots of spring pressure it doesn't matter.

MalcolmV8 said:

Unless you're running aftermarket springs with lots of spring pressure it doesn't matter.

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I was just going off Ed's recommendation to me even on stock stuff. He even recommended drilling the stockers out.

cj428mach said:

I was just going off Ed's recommendation to me even on stock stuff. He even recommended drilling the stockers out.

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I can't imagine why. I've never seen one fail. Of course it doesn't hurt to do it either.

Hey Malcolm regarding cams and overlap tuning do things vary a bit for turbo cars compared to blower cars, A bit of overlap sometimes helps out turbo cars, and they don't have that bypass valve underneath to mess with. Are turbo card a little bit easier to tune with cams?

s351 said:

Hey Malcolm regarding cams and overlap tuning do things vary a bit for turbo cars compared to blower cars, A bit of overlap sometimes helps out turbo cars, and they don't have that bypass valve underneath to mess with. Are turbo card a little bit easier to tune with cams?

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Yes totally different on a turbo car. They work very well with some overlap and drivability is no where near the issues on a PD blower car.

The higher iat2's is one of the main things that scare me away from aftermarket cams. Does that negative overlap help with that? I want to go at least 10:1 when I rebuild but had always planned on using stock cams.

Rambro said:

The higher iat2's is one of the main things that scare me away from aftermarket cams. Does that negative overlap help with that? I want to go at least 10:1 when I rebuild but had always planned on using stock cams.

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Honestly the higher IAT2s is a minimal thing I don't worry to much about. It's higher at idle and part throttle driving but who cares about that? WOT they're "normal" for your combo so it's not something to stress about. To answer your question a little negative overlap does indeed eliminate the reversion that causes it.
I have to say cams are a very expensive way to add power on these cars but if you've maxed everything else out then it's a good way to get some more.

I run the 106360s (230/232 @ .050) with quite a bit of overlap. I think that cam choice is great for a 10.x:1 engine with an aftermarket converter.