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

Quick timing question

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Old Jan 1, 2005 | 04:47 PM
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Default Quick timing question

Finally got around to checking the timing today on my 85 L98.
But I'm not sure if I'm reading this right:

Disconnected tan/black EST wire at the brake booster, and checked the timing mark...

Looking from the drivers side wheel well, the marks at the top down are 12 down to 0 then start climbing again up to 8.

Right now the base timing is set at that very bottom 8.
If I understand this correctly, I'm supposed to be at 6* BTDC. does this mean I'm at 8* ATDC???

So I need to jump 14* just to get back to proper base timing?
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Old Jan 1, 2005 | 05:42 PM
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If I am understanding you correctly, the answer would be yes. With timing set like that, it should start very easy, but not make much power.
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Old Jan 1, 2005 | 06:16 PM
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Originally Posted by Rich & Lisa_84
If I am understanding you correctly, the answer would be yes. With timing set like that, it should start very easy, but not make much power.
and is also hopefully the cause of a hesitation problem I'm having... I guess the last owner didn't understand the EST factor...

just wanted to make sure I'm reading this right... I almost couldn't believe it when I saw it...
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Old Jan 1, 2005 | 06:19 PM
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Originally Posted by mikey whipreck
and is also hopefully the cause of a hesitation problem I'm having... I guess the last owner didn't understand the EST factor...

just wanted to make sure I'm reading this right... I almost couldn't believe it when I saw it...
You might want to check the harmonic balancer to see that it hasn't spun on the elastomer. Assuming that it is OK, you're right on about the timing marks.
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Old Jan 1, 2005 | 06:43 PM
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Yes, that is correct, if you were in front of the car looking at the markings, 12 degrees BTDC would be the marking on the left and 8 degree ATDC is to the right.
I just finished installing a timing gear set and harmonic balancer because it had spun around the elastomer. I set my timing at 6 degrees BTDC and the car is running fine.
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Old Jan 1, 2005 | 07:51 PM
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Finished setting the timing at 6* BTDC...
Runs good, nothing broke, and my hesitation is gone.

I'm happy methinks
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Old Jan 2, 2005 | 12:47 AM
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If you like the 6 degrees BTDC, try 8 degrees BTDC timing. Then reset you TPS to .60 VDC. My 89 runs better with these settings as compared to the stock 6 BTDC and .54 VDC settings. The car wants to jump when you start to roll from a stop.
Happy New Year!
SAM
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Old Jan 2, 2005 | 01:59 PM
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Originally Posted by mikey whipreck
Finished setting the timing at 6* BTDC...
Runs good, nothing broke, and my hesitation is gone.

I'm happy methinks
Congrads.
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