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#1 |
![]() Join Date: May 2005
Location: Nichols, FL
Posts: 615
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![]() First Drivetrain Because of faulty DIS modules and the wiring differences between the 1988s and the production cars it took 2 ½ years to get the engine started. It turns out that the 2 DIS engineering samples Geoff had for this motor were bad. Once this was discovered I tried to use a 1990 DIS but it was not until someone forwarded me a copy of LT-5 wiring diagram for the 1989 pilot cars that I discovered there were/are wiring differences between the cars. The 2 major differences were the DIS modules are wired differently and the primary fuel pump on the early cars were controlled by the oil pressure sensor vice the ECM. Once these were corrected then the car would start and run. However starting proved to be a problem, There were 2 problems in the fueling system. The first was the ‘accelerator pump’ calibration event was extremely lean, I am running the original ECM and calibration map so I can only surmise the calibration was for non-alcohol formulated fuel and was just too lean. The second was the experimental injectors, they were designed before alcohol based fuels and over time they would break down and short out. During the troubleshooting process I would have occasions where the injectors kept injecting fuel while the ignition was in the run position. Until this was discovered and corrected there was considerable ‘bore wash’ and cam wear due to fuel diluting the oil. Needless to say it was a disaster waiting to happen and I kept my eyes open for a fix which happened in August 2011.
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55 Polo White (Project) 61 Jewel Blue (Sold to buy above) 66 Nassau Blue 68 Torch Red 88 ZR1 Blue 90 ZR1 White |
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#2 |
![]() Join Date: May 2005
Location: Nichols, FL
Posts: 615
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![]() Second Drivetrain In Sept 2012 I took the engine and Queenie to Geoff for an engine retrofit using the motor from EX5010. He confirmed my suspicions concerning engine wear and using the chains and crank from the earlier motor went through the EX5010 motor and completely rebuilt the motor. This motor and the pilot line ZF are what is installed today hopefully someday the roadster owner will contact me and I can swap out the 1989 pilot ZF for the early ZF in his car which would complete a long journey.
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55 Polo White (Project) 61 Jewel Blue (Sold to buy above) 66 Nassau Blue 68 Torch Red 88 ZR1 Blue 90 ZR1 White |
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#3 |
![]() Join Date: May 2005
Location: Nichols, FL
Posts: 615
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Since there has been little activity here I figured I would provide an update to this story. In April I picked up the car to take it to the NCM for display. Geoff had not gotten the car started so I took dis, ecm and coil packs just in case. I pulled the plenum, check the dis with my checker, replaced the coil pack, made triple sure the wiring was right and put it back together. It started but sounded like a thrashing machine!! Instead of using the heads off 5010 as I had asked he used the heads that were on the car after having a local machine shop do a valve job. The machine shop cut the valves down so much that one cyl had no compression and all the lifters were collapsed so much they would not pump up.
Never buy a trailer without a winch! We winched the car on the trailer and she is on display at the NCM with a date in Sept to get the other heads put on. Just as aside Geoff said GM paid about $250,000 each for the 25 Phase II motors during the development process. So one of these versions in running condition is a real rarity, well there are 2 that do run out there. Tyler
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55 Polo White (Project) 61 Jewel Blue (Sold to buy above) 66 Nassau Blue 68 Torch Red 88 ZR1 Blue 90 ZR1 White |
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#4 |
![]() Join Date: Apr 2013
Location: Toronto
Posts: 716
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Wow . Just reading this info now . Cool beans . Thanks
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#5 |
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,697
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Awesome story Ty.
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[SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX |
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#6 |
![]() ![]() Join Date: Feb 2010
Location: Pendleton, IN
Posts: 3,904
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I'm so sorry your engine work was sub par. You deserved better than that, for sure. I'm glad EX5023's Phase II is purring smoothly.
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1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project |
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