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Old 08-12-2012, 08:53 AM
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F-BIRD'88 F-BIRD'88 is offline
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95 lbs is what I have researched to be the correct compression reading with 114 lobe separation.The bore is stock 4.25, original forged aluminum pistons 8.75 compression.

Don;t know that you have been reading. I had a 8:1 BBC with a bigger cam than you got (old nitrous motor) and it had a lot more than 95psi.
Your .650" lift BBC cam is 255in 265ex @.050" +/- 3deg. its not big
The ring seal is dead. You did more than cook a valve.
You scuffed the rings (butted) when it ran lean.
if the ring lands are not broken they are probabily distorted too. ( jammed rings)

95psi indicates a ****ed motor. (Parden my french) Much lower and it won;t even start.

If the ring seal was good the thing would not be huffing out the breathers.
The 454HO pistons are not suitable for hard supercharging (especially with a bad tune up and or crap gas) I was under the impression they were cast.

top ring end gap should be .032"
Get some JE or Venolia pistons if you want to lean on it that hard.
Flat top or forged dished.

Last edited by F-BIRD'88; 08-12-2012 at 09:09 AM.
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