[James]

This is what I had measured. The result will vary as additional repairs is perform. Is to be used as a point of interest for anyone that is curious.

The following work was performed:
• Head is used with unknown service life.
• Cleaning everything and lapping the valves.
While disassembled the following measurement was performed:
• Mic the intake and exhaust port throat diameter.
• Mic the valve heads and stems diameter.
• The max the valves will open before hitting the deck. Intake: .467” and Exhaust .403”. Intake look like it was recess into the head a little.
Head Specs:
• Intake Head Dia.: 2.254”
• Intake Stem Dia.: .371”
• Intake Port Throat Dia.: 1.995”
• Exhaust Head Dia.: 1.908”
• Exhaust Stem Dia.: .434 Sodium Filled
• Exhaust Port Throat Dia.: 1.680”
Head was reassembled with valve checking springs. Head was mounted on the SuperFlow 110 flow bench. The head was first flowed with a 4.250” diameter bore (same as a 305 cu. in V6). Then the head was flowed on a 4.700” bore (the biggest size for this flow bench). This was done to see if the smaller bore would shroud the valves flow.
The following checks was performed:
• Low intake/exhaust valve lift (.010” through .120” lift in .010” increments) for cfm and swirl (swirl only on the intake valve).
• Intake/exhaust valve lift (.050” through .450” lift in .050” increments) for cfm and swirl (swirl only on the intake valve).
After the flow bench the valve spring was installed. Then following was performed:
• CC all combustion chamber. Came up with an average of 117.0 CC.
• CC all intake ports. The two port that is side by side share their volume due to the PCV valve and the divider between the port is recessed a little. The total was divided by 2. The average size was 298.5 CC.
• CC only one exhaust port. The center port is part of the heat crossover system. The exhaust port size is 125.6 CC.
Results:
• Base on the 305E V6 bore and stroke the compression ratio had drop from a measured 7.4:1 to 6.8:1 when a magnum head is installed.
• The result on the 4.250” bore low lift swirl results may be due to the small-bore size. Instead of swirling it may have been tumbling (I do not have a way to measure this).
• See the attached charts for the flow and swirl results.