2001 Pure Stock Drags

[COPO PETE]

See that Rob....you know, about chambered exhaust! Anyway thanks for your answer Andrew, it still brings a smile to my face,but it's not a option. And while I'm being a pain in the a$$, does anyone know anything about the story in High Performance Cars on the ZL-1? It's suppose to be the July 69 issue. And Stan, thanks for all your effort. I appreciate it!
Peter

[Chevy454]

Yeah, yeah...if you Canadians wouldn't be so secretive about that ultra hi-tech exhaust technology you have been hiding for years, then maybe us "Show-Me boys" would be in the 12s !

Oh, on a sie note (Pete & JJ will LOVE this!): Remember when I checked my dwell before our match-ups on Saturday? Well, turns out I have been hooking up the dwell meter wrong! Who KNOWS what my dwell was at! Maybe Dave Greene is right...maybe I do have a lot to learn ...!

[COPO]

Stan, I had heard the chambered exhaust was restrictive, but never dreamed it would cost 80+ horsepower. Anyone would certainly think twice before using it.

[Edited by COPO (09-25-2001 at 07:38 PM).]

[Rowdy Rat]

Pete,

Not a problem at all... Glad to help out!

The camshaft information that I have is as follows:

#3925535 (First Design L-88)

VALVE LIFT

Intake - .540" (includes lash - .022")
Exhaust - .560" (includes lash - .024")

VALVE TIMING

Intake
Opens (BTC) 55

Closes (ABC) 102

Duration 337


Exhaust
Opens (BBC) 98

Closes (ATC) 68

Duration 340


#3959180 (Second Design L-88/ZL-1)

VALVE LIFT

Intake - .560" (includes lash - .024")
Exhaust - .600" (includes lash - .026")

VALVE TIMING

Intake
Opens (BTC) 62

Closes (ABC) 105

Duration 347


Exhaust
Opens (BBC) 106

Closes (ATC) 73

Duration 359


As noted above, the lift figures include valve lash and the opening and closing points are measured (I believe) .004" off the base circle.

Still working on that magazine article...

Regards,

Stan

[JLerum]

Well, I have returned with some results for an LS-6/L-72/L-78 cam. Tuesday I made the trip over to a friends business that has a cam doctor. This equipment is unique in that it will measure a cam at derived points selected by the operator. All measurements are made and printed out on a PC.

The cam that was used was purchased from GM in Dec of 1982. I think youÃll be surprised by the tolerances of this 3863143 cam. The printout from the cam doctor came out as such.

************************THE CAM DOCTORÃS ANALYSIS****************

Cylinder # 1 .050 check height
Part Number 3863143

Intake & Exhaust
Lobe center separation = 111.4 cam degrees
Valve Overlap = 13.9 crank degrees

Intake
Valve Opening = 8.6 œBTDC
Lobe Center = 111.4 œATDC
Valve Closer = 53.1 œABDC
Duration = 241.7 Crank Degrees
Max Cam Lift = .30516 In
Net Valve Lift = .500 In
Lobe Area = 27.36 In * DEG

Exhaust
Valve Opening = 57.5 ŒBBDC
Lobe Center = 111.4 ŒBTDC
Valve Closer = 5.3 ŒATDC
Duration = 242.8 Crank Degrees
Max Cam Lift = .32126 In
Net Valve Lift = .524 In
Lobe Area = 27.6 In * DEG



Notes: Intake .024 hot lash/ Exhaust .028 hot lash
Net Valve Lift=(Max Cam Lift x 1.72)- hot lash
Rocker Arm ratio= 1.72




I thought it was very interesting that a cam that is suppose to have a lobe center separation of 114 degrees cam out to 111.4. This car would idle a little rougher than a cam with 114 degrees. If you noticed that the camÃs exhaust lobe is a little taller than itÃs suppose to be. In a perfect world with a perfect cam the hot lash it should come out to .492. net valve lift. This imperfect grind on the exhaust side should be beneficial to some performance. I have the numbers of this cam at .020 which I'll post in the near future.


Jim