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#1 |
![]() Join Date: Feb 2011
Location: San Marcos CA
Posts: 1,802
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I have driven or ridden in about half a dozen ZR-1's and everyone of them had a different personality and seemed to have different torque characteristics. Some were real soft down low and fairly "top-endy". My car has a great grunt at 4000 rpm but is a little flat on the top, and the car I drove last Saturday had normal to good mid range and super great top end and it was still on factory 91 manifolds (Erik-YZPilot's 91). Erik's car has the same timing curve as mine seeing as how I made the chip for it so pretty much all things being pretty equal with a similar home grown plenum and inj housing port job, same chip, same weight, same car, etc...
I'm seriously considering degreeing the cams on my car to make it run better. This is of course assuming that there are gains to be realized there. I'm very much thinking that this is the silver bullet to Permagrin and the intangible difference and the mysterious reason some cars have the extended torque peak/cylinder pressure and others are just 'ok'. I'm remember reading this is easiest with the engine removed? btw, I think I'm going to keep this car assuming I can keep it smogged in this state. If I can get it to run like Erick's I would drive it a lot more often. |
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#2 |
![]() ![]() Join Date: Aug 2009
Location: South Dakota/California
Posts: 3,794
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I would say impossible to do with engine in car But you are welcome to give it a try and let us know how it works out for you. You have to somehow install two mechanical chain tensioners and Cam Covers removal with engine in car is no fun.
Of several 90's I have checked, none required Camshaft Timing as my LT5 engine In Car Inspection of Timing was within 1.5 degrees for each Camshaft. Checking your Camshaft Timing Engine IN Car Checking Camshaft Timing Engine In Car You have to remove Cam Covers engine in car...then set up to determine or assume the current TDC timing Marks on the Harmonic Balancer are correct. You can get close without pins in front camshaft retainers just by using a flashlight observing the pin hole in the camshaft journals alignment with the holes in the camshaft front retainers. If you want to make sure of the TDC marks on the Harmonic Balancer, you can install a dial gauge to determine when piston #1 is TDC to determine TDC easy enough engine in car and can then mark harmonic balancer and use degree tab bracket easy enough engine in car. The Tab has marks 25 deg Before and 5 deg After TDC (A total of 30 deg). You can use the marks on the Timing Tab to mark your Harmonic Balancer. Mark 110 deg BTDC by rotating the Harmonic Balancer 3 complete Tabs (90 deg) + 20 deg Counter Clockwise and mark. Mark 114 deg ATDC by rotating the Harmonic Balancer Clockwise 3 complete Tabs (90 deg) + 24 deg and mark. See Item #2 Camshaft Timing ![]() You can check by rotating engine (with chain tensioners still keeping chains tight) by visual inspection in pinning holes which can be done engine in car easily. If you mess around too long especially reversing the rotation of the crankshaft, the Timing Chains will loose their hydraulic chain tensioner tension. I set the pins in the Venier Plate slot such that the camshaft sprockets are rotated against the half moon on the camshaft (clockwise looking at front of engine) which prevents additional movement of sprockets on camshaft under any conditions. This is within 1.6 degrees of where I want the timing. See item #5c and #7a of LT5 Camshaft Timing Additional Tricks ![]() CAMSHAFT TIMING USING DEGREE WHEEL Camshaft timing TIPS Dial gage holder TIPS LT5 Camshaft Specifications and Camshaft Timing Tricks Tech Info - LT5 Summary of Camshaft Timing from Start to Finish Tech Info - LT5 Timing Diagrams Tech Info - LT5 Camshaft Timing and Timing Chain Calculations Setting/Installing the Chain Tensioners and Timing Chain Tricks Camshaft timing optimum deg Cam timing First attempt at camshaft timing
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Left Clickable links ![]() -Solutions- LT5 Modifications/Rebuild Tricks Low Mileage ZR-1 Restoration 1990 Corvette (L98) Modifications LT5 Eliminated Systems LT5 Added Systems LT5/ZR-1 Fluids 1995 LT5 SPECIFIC TOP END REBUILD TRICKS Last edited by Dynomite; 12-23-2014 at 11:24 AM. |
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#3 |
![]() Join Date: Feb 2009
Location: Alexandria, Virginia
Posts: 1,467
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I just had the cams timed on my new motor and the first step is to pin the motor as they do at the factory to set the timing. We then set up the degree wheel and a dial indicator and the drivers side intake cam was retarded almost 7 degrees!! The other three cams were not as bad, only 2-3 degrees out. I can kind of see why GM is resisting releasing any dyno sheets if the #'s can vary this much.
Rich
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1990 Bright Red Coupe #608 380 Stroker, Ported Heads/Intake/Housings/TB Haibeck Secondary Delete Chip / Pete's Cams George Braml Intake / FIC Injectors Coated SW Headers / Corsa Bill Boudreau B/B ZF6 / Viper 4.10 gears Ron Davis Radiator Pioneer AVIC-Z140BH NAV Fikse FM5's 285 / 335 / C6 Brakes WAZOO Member |
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#4 | |
![]() Join Date: Feb 2011
Location: San Marcos CA
Posts: 1,802
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#5 |
![]() Join Date: Jan 2006
Location: Niceville
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I agree they all have their own personality. Others can comment on specifics of what gives what. Here's what I found on a '93.
Cam factory...pinned/degree'd Rt Intake 110.5...112p/114 Rt exhaust 110...113p/110 Lt intake 115.5...111.5p/114 Lt exhaust 110...112p/110.5 I didn't drive car hard before as it had a stuck lifter. Ted |
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#6 |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
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FWIW, Mike, Marc Haibeck said he did one in place with the help of a video camera. But, he also said he wouldn't do it that way again, given the choice: easier to take the motor out!
Timing is specific to the performance characteristics. To that topic, Marc Haibeck published a paper on cam timing which addresses FAQs. However, the short story is there is considerable "gold" in that thar cam timing!!! (See article from Haibeck website). Also, it requires new cam bolts each time the phasing/timing is changed as they're torqued to stretch.
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#7 | |
![]() Join Date: Feb 2009
Location: Alexandria, Virginia
Posts: 1,467
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Rich
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1990 Bright Red Coupe #608 380 Stroker, Ported Heads/Intake/Housings/TB Haibeck Secondary Delete Chip / Pete's Cams George Braml Intake / FIC Injectors Coated SW Headers / Corsa Bill Boudreau B/B ZF6 / Viper 4.10 gears Ron Davis Radiator Pioneer AVIC-Z140BH NAV Fikse FM5's 285 / 335 / C6 Brakes WAZOO Member |
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#8 | |
![]() Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,385
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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#9 |
![]() Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
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8K+ miles on my Jerrys cam bolts, no issues......they were torqued and reset twice
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#10 |
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Location: San Marcos CA
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