Drawing a Chevy Small Block Piston

8/13/2019 Drawing a Chevy Small Block Piston

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Drawing a Chevy Small Block Piston.

Start a new sketch on the Front Plane. Draw a vertical reference line at the origin then start sketching a

rectangle starting at the origin. Apply your height and width dimensions. Your width will be half your

final diameter. 1.9698 is 2% reduction from a 4.02 std bore piston. Next draw the ring landings applying

the constraints shown to reduce the number of dimensions needed. Once they are fullydimensioned(lines will turn black), use the trim command to remove the area shown.


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Exit the sketch and perform the revolve operation using your vertical line as the revolve axis.


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Start a new sketch on the Top plane for the piston pin reliefs. Project the diameter of the piston by

selecting the edge and using the Convert Entities button. Draw a vertical construction line at the origin

and one that is 1” away to the left.

Trim these lines so they are only inside the circle.


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Draw an arc using the intersection points of your vertical reference line(1” away line) and give the arc a

4” radius.

Add two horizontal lines and a vertical line to show the pin material.


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Then trim until you have this shape.

Exit the sketch and use the Extruded Cut operation and cut 1.5” away from the main body. Then apply

fillets of whatever dimension you like starting with these two edges.


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Then these

Then finally the bottom two.


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Mirror your extrude and all three fillet operations across the Right plane

Start a new sketch on the Top plane. Select the face of the piston shown in blue below and use the

Offset Entities button. Set your offset to a number that looks reasonable(.0625 is what I used).


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Exit the sketch and extruded cut that sketch 2” into the body.


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Start a new sketch on the Front plane. Project one of the faces where your piston pin will go using the

Convert entites after you have selected its face. Add a line from the bottom left to top right of the

rectangle and make all of these lines construction lines. Add a circle at the center point of this line you

just added and make it your piston pin diameter.

Exit the sketch and extruded cut that. Change the direction1 drop down box from Blind to Through All,

check the Direction2 box(will automatically go Through all).


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Start a new sketch on the front plane. This is going to be one of the valve reliefs. Convert the top edge

of the piston with the Convert entities button and make it a construction line. Add a line so you can

create a new plane ad an angle for your valve reliefs.


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Create a new plane using the Front plane and that 15degree line. In the work plane dialog box input

90degree for the angle.

Dimension two circles so they fall on the piston where you want. Typical small block chevy valve sizes

are 1.6” for the exhaust and 2+” for the intake.


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For the extruded cut you will probably need to extrude using two directions. This will depend on where

your plane is and how deep you want to make the reliefs.

And there it is.


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Drawing a Chevy Small Block Piston

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