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031
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Discussion Starter #1
did a compression test on the 565 BBC. Should have done a leakdown but I didn't. 13 to 1 motor. All cylinders tested 200 to 210 except for #7, it was 240. Re-checked 3 times. Any ideas motor gurus?
 

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Boat Nut
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any evidents of excess oil in the cylinder? leaky valve guide??
 

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Is it a new motor? Its not uncommon for the lash to need adjusting after the first few runs then it should stay pretty consistent unless something is going south. What prompted the compression test?
 

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031
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655 Posts
Discussion Starter #6
Motor has 2 seasons on it. Ran at least 20 bottles of nitrous through it last summer [250 shot]. Tearing it down tomorro to check rings & bearings
 

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Spiral out
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that was my first thought, exhaust valve opening late maybe. Lash was good at 024
I'm thinking the cam may have been made incorrectly (#7 intake lobe centerline a few degrees advanced.....for some unknown oversight).

Intake closing is what initiates compression.

Check it when you have it apart.
 

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I'm thinking the cam may have been made incorrectly (#7 intake lobe centerline a few degrees advanced.....for some unknown oversight).

Intake closing is what initiates compression.

Check it when you have it apart.
I haven't personally seen this but it is a definate possibility.
 
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