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350HP930 350HP930 is offline
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Join Date: Jun 2003
Location: St Petersburg, FL
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Tonight I broke out the internal calipers and went in search of the differences between the worst and best flowing heads.

I was pleased to discover that all major dimensions and curvature profiles were the same but I was perplexed as to why the flows would be so different.

Upon further visual inspection I noticed a very subtle difference of the short side radius where it meets the valve seat.

It appears that there is a minor difference in the castings resulting in almost a millimeter difference in the location of the port and a corresponding increase in the length of the short side radius. I guess its enough to cause the measured 1.5% flow difference.

I have attached a picture below to show the difference and I will be spending some time in the shop tomorrow trying to match them up.
Old 04-15-2005, 09:07 PM
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