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Author
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Topic: Z303 CAM TIMING...??
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RED@7kVERT *8850GT*
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Member # 5909
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posted
 
 
With all of the usual stuff. FULL intake/exhaust, good heads (AFR 185's/TW's).... should a Z cam be installed straight up or retarded a bit??
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02 Z06-11.0 @ 132 1.9 60'
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Sold:05 CTS-V-13.1@114
Sold:01 Cobra Vert-12.0@119
Posts: 2432 | From: -916- | Registered: Aug 2005
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93PONY
Mr. Valve Events
Member # 60
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posted
The Z is what....228/228 112LSA?
4 degrees of overlap @.050 lift.
Advanced 5 degrees (107ICL).
To answer your question it really depends on the setup. AFR heads for instance have a MUCH more efficient exhaust port than TW's or Edelbrocks & as such require much less exhaust duration on the camshaft than a TW or Edelbrock to flow the same amount of air. The exhaust port on the head is only one aspect to consider....it's really about the entire exhaust system. Stock headers/H-pipe would require more lobe to expell the same amount of exhaust gasses as a Longtube/off-road setup.
But the real kicker is the intake manifold. By design the 5.0 EFI intake manifolds are extremely restrictive. The more bends, the more restrictive. Compared to a typical Carburated manifold the 5.0 EFI has an extra 180 degree bend slowing down the air. Couple this with a relatively small plenum volume to displacement ratio & you end up with a very restrictive design. This is why most Carb setups make more power with smaller parts.
Case in point the 3 N/A 10 second 347's on the fastest list. All with 10.5-11:1 compression, same 347 cubes, all with longtubes, off-road exhaust, all 5spd cars, all around the same MPH in the 1/4. 2 cars run ported VicJr heads (215-225cc intake runner volume) & fully ported Vic EFI intake manifolds. Both of these cars run massive camshafts (244+ duration)These 2 cars make peak power at or before 6400rpm. The 3rd car runs competition ported AFR165's (175cc's) with a much smaller camshaft yet makes peak power higher in the RPM band....with smaller parts. It's really amazing what a good intake can do.
Now, back to your question....Given that the camshaft is already advanced, I'd say if you're running an off-road exhaust of any kind & a typical 5.0 EFI intake (not a spider or box) then at the very least I'd retard the camshaft 4-5 degrees. If it was carburated, there's really no need to retard the cam....although again, given a really free-flowing exhaust port (like the AFR's) it probably would pick up a little from retarding it 2-3 degrees. Really depends on the rest of the combo.
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www.advancedenginedevelopment.com
SCT dealer
Dynotuning
(916)715-7569
Posts: 4265 | From: Fair Oaks, CA | Registered: Nov 2000
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1sick65
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Member # 3957
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posted
so will it make his car faster if he has shorties with a rpm 2 and 3.55's?
Posts: 1457 | From: Sacramento,CA | Registered: Jan 2004
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RED@7kVERT *8850GT*
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Member # 5909
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posted
To be specific RPM 2 manifold, 70mm TB, 77 MAF/ longtube off road exhaust. with the appropriate supporting fuel and ignition systems.
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02 Z06-11.0 @ 132 1.9 60'
_ _ _ _ _ ____ _ _ _ _ _
Sold:05 CTS-V-13.1@114
Sold:01 Cobra Vert-12.0@119
Posts: 2432 | From: -916- | Registered: Aug 2005
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93PONY
Mr. Valve Events
Member # 60
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posted
I'd retard the Z 6 degrees with AFR's & 4 degrees with any other head.
It'll idle better, have more bottom/midrange punch & pull a little higher in the RPM. (more power up top too)
There are no shorties that I know of that can swallow the wide AFR exhaust port. Even longtubes must be ported at the flanges to swallow the AFR's. Having a wall (blockage) at the header flange will cause some form of exhaust reversion....limiting low/midrange power.
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www.advancedenginedevelopment.com
SCT dealer
Dynotuning
(916)715-7569
Posts: 4265 | From: Fair Oaks, CA | Registered: Nov 2000
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93PONY
Mr. Valve Events
Member # 60
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posted
As for shorties vs longtubes.....probably longtubes would make more power over all.
Although I've run 11's on the stock bottom end N/A with Edelbrock performers & shorty headers @3300lbs raceweight. Shorties can still make plenty of power. Just make sure they're not a blockage to the exhaust port.
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www.advancedenginedevelopment.com
SCT dealer
Dynotuning
(916)715-7569
Posts: 4265 | From: Fair Oaks, CA | Registered: Nov 2000
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90lxfoxbody
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Member # 6947
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Im making just at 330whp on tw head super comp shortys system max intake 70 mm t body and 77 mass with a tiny cam 218 224 at .050 478 488 lift.I would say this combo with the rest of my car would put me in the 11s pretty easy at 3000lbs.
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Owner Of All Out Performance
Ya I own that Cobra
Old setup whipple and jug 9.37 155
New twins hoping for 8.50s at 165
Posts: 588 | From: fresno ca | Registered: Jul 2006
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