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Spark Knock at 10PSI? 92/93 Fuel

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Old 10-08-2017, 10:46 AM
  #21  
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https://imgur.com/a/oKKdP
Left->right 1234

#4 threads are covered in oil, probably just the valve cover gasket but worth noting I guess.

About to get a leak down now
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Old 10-08-2017, 06:46 PM
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Compression seems fine. I couldn't run a leakdown cause the harbor freight tool uses industrial style fittings and all my **** is "aro" style.

Cold Compression:
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Warm Compression:
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I re-timed the engine. I'm gonna get the right adapter for the leakdown and see what it says.
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Old 10-08-2017, 07:29 PM
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Scope pics. #4 looks really wet. I wasn't using flood protect so it might be fuel. But #4 plug was wet too.
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Old 10-09-2017, 10:21 AM
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Those compression numbers are VERY low. You should be around 160-190 in that range. What CR are your pistons?
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Old 10-09-2017, 10:22 AM
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8.6:1 pistons, 00 head on 96 block.
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Old 10-09-2017, 10:25 AM
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Originally Posted by Onyxyth
8.6:1 pistons, 00 head on 96 block.
Well that may explain a lot since your CR is lower than the stock. It is even across the board which is good though.
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Old 10-09-2017, 10:34 AM
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Yeah I think the compression is reasonable for my CR. And it's very even. Gives me a bit of hope.

Do any of the scope pics look like there's pitting? It's so hard to tell if it's pitting or just carbon build up. I guess my options are really just run it, or rebuild it. I still need to get the leakdown done today (gonna try to find the correct fittings at the homeless despot).
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Old 10-09-2017, 10:34 AM
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Numbers don't matter much, consistency does, his look consistent.
And besides that's an HF tester which is known to read notoriously low.
Originally Posted by Onyxyth
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Do any of the scope pics look like there's pitting? It's so hard to tell if it's pitting or just carbon build up. I guess my options are really just run it, or rebuild it. I still need to get the leakdown done today (gonna try to find the correct fittings at the homeless despot).
Just send it (run it)
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Old 10-09-2017, 10:39 AM
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Realistically that's what I'm gonna do. I'm gonna do a few oil changes and just crank the boost up.
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Old 10-09-2017, 10:39 AM
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Originally Posted by 18psi
Numbers don't matter much, consistency does, his look consistent.
And besides that's an HF tester which is known to read notoriously low.


Just send it (run it)
Correct, in a follow up post I did say his numbers are even across the board which is good, just lower numbers than I would have expected initially.

OP :

I wouldnt worry about rebuilding the engine just run it. The pistons just look like its a lot of carbon buildup. Hard to tell if there is pitting in the pictures.
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Old 10-09-2017, 11:13 AM
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The only thing that saved you was 8.6:1 can't imagine how quick it would have scattered at 9.0:1
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Old 10-09-2017, 07:30 PM
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Leakdown was 20% cyl1 40% 2-4, cold. All blowby. Machine shop set the ring gap loose, maybe that's some of it. Still gonna send it.
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Old 10-09-2017, 08:56 PM
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Since the leak down is so high you have to run at least 20 psi to make up for it. Send it bro!!
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