Thread: 383 build-Something Caught My Eye

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Richard those pistons are not 18's.They are 9.71 c/r with 64 cc heads.

Originally Posted by 1gary

Richard those pistons are not 18's.They are 9.71 c/r with 64 cc heads.

We are not concerned with what they make with 64cc heads, you don't have 64cc heads.
Gary, let us start from ground zero.

1.You are building a 383. The bore is 4.030" and the stroke is 3.75". If we multiply that out, we find: (.7854 x 4.03 x 4.03 x 3.75 x 16.387 = 783.84 cc's).

2.The heads you are currently planning to use have 72cc chambers.

3.According to the KB site, the pistons you have chosen to use have 18cc crowns....
Icon Forged Racing Pistons
This piston is an open dish design with no squish pad. Look at the illustration I linked.

4.Piston deck height is 0cc's.

5. Not knowing the head gasket you plan to use, but estimating the compressed thickness at 0.040" and the I.D. at 4.100", we can compute the cc's thusly....
(.7854 x 4.1 x 4.1 x .04 x 16.387 = 8.65cc's)

Now, we add up all the values. (783.84 + 72 + 18 + 0 + 8.65 = 882.49cc's). This is the total volume pushed into the cylinder by atmospheric pressure with the intake valve open.

Now, we add up all the values with the piston at TDC, eliminating the cylinder volume. (72 + 18 + 0 +8.65 = 98.65cc's)

Now, we divide the larger by the smaller (882.49 / 98.65) and find 8.94:1 static compression ratio.

Math is black and white Gary, there are no gray areas.