C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

timming a 1990 L98

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Old 03-17-2015, 11:38 PM
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bigj177
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Default timming a 1990 L98

how do you properly set the timing on a 90 vette. i tried to follow the workshop manual. but had no luck. does anyone have a proper procedure.
Old 03-18-2015, 12:12 AM
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Cliff Harris
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Unplug the EST connector.
Connect timing light to spark plug wire #1.
Loosen distributor hold down clamp enough that distributor can be rotated.
Start engine.
Shine timing light at harmonic balancer and move the distributor until the harmonic balancer line aligns with the 6° mark on the timing tab.
Tighten distributor clamp.
Recheck timing to make sure the distributor wasn't accidentally moved while tightening the clamp.
Connect EST connector.

Having the EST connector open while the engine is running will set an error code 42 and the Service Engine Soon light will come on. You can ignore this and the SES light will not show up again or you can reset the ECM to clear the error code.
Old 03-18-2015, 05:37 AM
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bigj177
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Which is the est connector. Is it the big plug behind the distributor. If so, I disconnected it and tried starting the car. It didn't want to start.
Originally Posted by Cliff Harris
Unplug the EST connector.
Connect timing light to spark plug wire #1.
Loosen distributor hold down clamp enough that distributor can be rotated.
Start engine.
Shine timing light at harmonic balancer and move the distributor until the harmonic balancer line aligns with the 6° mark on the timing tab.
Tighten distributor clamp.
Recheck timing to make sure the distributor wasn't accidentally moved while tightening the clamp.
Connect EST connector.

Having the EST connector open while the engine is running will set an error code 42 and the Service Engine Soon light will come on. You can ignore this and the SES light will not show up again or you can reset the ECM to clear the error code.
Old 03-18-2015, 06:40 AM
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bjankuski
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Originally Posted by bigj177
Which is the est connector. Is it the big plug behind the distributor. If so, I disconnected it and tried starting the car. It didn't want to start.
It is a single tan wire with a black connector located between the brake booster and the engine on the drivers side of the car. (Near the firewall)
Old 03-18-2015, 01:05 PM
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bigj177
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I didn't notice like that, back their. Would it be possible to get a pic of it


Originally Posted by bjankuski
It is a single tan wire with a black connector located between the brake booster and the engine on the drivers side of the car. (Near the firewall)
Old 03-18-2015, 11:22 PM
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Cliff Harris
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Here's your guy (between the brake booster and the windshield wiper motor -- tan wire with black stripe):

Old 03-19-2015, 07:04 AM
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bigj177
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Thank you very much


Originally Posted by Cliff Harris
Here's your guy (between the brake booster and the windshield wiper motor -- tan wire with black stripe):

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