If the cylinder head is machined and over .010 is removed, the holes in the intake manifold and the cylinder head will not line up when reassembled. To correct this condition, it is necessary to machine surface "B". The amount that must be removed varies with the degree at which the head is machined. The chart below shows the amount which must be removed from the intake side of the cylinder head so that the holes will line up.

For example: Let's assume.015 was removed from surface "A" on a Ford OHV cylinder head. Surface "B" (Figure 1) as shown below is at 10° angle to surface "A". Using the formula listed below we proceed as machine the intake manifold side of the follows:

Multiply the .015 removed by the 10° multiplier which is 1.2 and we arrive at the proper amount to remove from the intake manifold side of the cylinder head.

Example: .015
        X 1.2
          030
         0150
        .0180 Amount to be removed on intake side "B"

The same amount must be removed from both cylinder heads or the holes in the intake manifold will not line up properly.

HEAD ANGLE IN DEGREES

  5° Amount Removed at "A" X 1.1 = Amount to be removed at "B"
10° Amount Removed at "A" X 1.2 = Amount to be removed at "B"
15° Amount Removed at "A"X l.4 = Amount to be removed at "B"
20° Amount Removed at "A" X 1.7 =Amount to be removed at "B"
25° Amount Removed at "A"X 2.0 = Amount to be removed at "B"
  30° Amount Removed at "A" X 3.0= Amount to be removed at "B"
35° Amount Removed at "A"X4.0 =Amount to be removed at "B"
   40° Amount Removed at "A" X 8.0= Amount to be removed at "B"

(P20)