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.030" squish on high compression?

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Old Dec 17, 2009 | 01:32 PM
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Default .030" squish on high compression?
Building 103" and wanted to check with some guys on what squish they are using when installing high compression 10.5 :1 pistons, deck height 0". In order to keep good flow in the heads and run cooler I want .030 squish. Anyone run this in their build? Am I wrong on the squish?
 
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Old Dec 17, 2009 | 03:08 PM
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My builder used 0.035. His comment was that it would provide a better burn for the charge. I'm not an engine builder, but you asked.........
 
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Old Dec 17, 2009 | 03:15 PM
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Me too. From what I understand, .030 may be a bit tight on these air cooled engines. Carbon tends to build up on the piston tops and can trigger detonation if the squish is too tight. .032 - .035 seems to be the safer range. Having said that, my limited knowledge says that .030 is the very minimum you should use.
 
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Old Dec 17, 2009 | 03:20 PM
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Been using .030 for years. I've even used .027.

If you can get .030, that's the sweet spot... but WTF do I know...???...
 
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Old Dec 17, 2009 | 05:06 PM
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.030 has been the standard for high compression harley motors. If you are careful about warm ups and make sure it is fully warm before dropping the hammer you can go smaller. I doubt there is really much actual diff between .030 and .035 unless you are vying for a world drag championship.
 
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Old Dec 17, 2009 | 05:11 PM
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Originally Posted by PhilM
but WTF do I know...???...
Hell if I know.... lol.
 
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Old Dec 17, 2009 | 06:03 PM
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I'm at .032 on my 103". It's 10.5:1 with 205ccp on last check. Pistons were down .005 and I'm using a .027 MLS head gasket. Seems to work great for me.

Zach
 
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Old Dec 17, 2009 | 06:10 PM
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I forgot to mention I will be using the stock heads after re-cut vlv seats for flow and port / polish.

Question for Phil: Have you ever polished the intake manifold for better flow and did you get the results you expected?

Thanks for the responses so far.
 
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Old Dec 17, 2009 | 06:11 PM
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Originally Posted by Biggzed
I'm at .032 on my 103". It's 10.5:1 with 205ccp on last check. Pistons were down .005 and I'm using a .027 MLS head gasket. Seems to work great for me.

Zach
What cam are you running?
 
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