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#51
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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
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Pete Simpson 1962-2013 RIP Owen Simpson Eric Simpson |
#52
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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 ![]() |
#53
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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).] |
#54
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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 |
#55
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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
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1970 LS-6 Chevelle Going fast on Goodyear Polyglas. 12.21 @ 115.32 PSMCDR 2009 12.24 @ 114.30 PSMCDR 2010 |
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