Thread: Convert a chev 283 to 307 or bigger

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Originally Posted by martycar

Hello Techinspector1 thank you for your wealth of information, you have given me plenty to work with.
Some of your terminology or lingo I'm still trying to work out, what is squish
Thanks Martycar

It is desirable to have the piston come up very close the the underside of the cylinder head to "squish" the fuel/air mixture over into the combustion chamber, thereby mixing and homogenizing the mixture, eliminating rich and lean areas so that ALL the mixture gets lit off and burns at the same rate. The result is good detonation-resistance, fuel mileage and power. A builder needs to use a piston that has a nice, flat, generous squish area on the crown of the piston, so piston choice is critical.
Here's an example of a piston that you do not want to use. It has only a very thin band of flat piston area to mate with the underside of the head.....
http://hotrodenginetech.com/wp-conte...L92pistons.jpg
Here's an example of a piston with a generous flat area on the crown to facilitate a good squish. The squish plateau is on the left side of this piston in the photo.....
http://raybarton.com/parts/media/cat...street-flat.jp
Here's an example of a dished piston to lower the static compression ratio of a build. See the flat area on the left of the piston?
http://static.summitracing.com/globa...39632-8_ml.jpg
Think of squish as dropping a book flat down onto a table. You can visualize how the air is "squished" or "jetted" from between the book and the table. Some fellows will refer to this as quench, but I feel that squish is a better term to use.

On a small block Chevy, extensive research has proven that the ideal squish clearance measurement is between 0.035" and 0.045", so when engineering a build, that's what you should shoot for. You adjust that figure with the piston deck height (how far down in the bore the piston is when it is at top dead center) and the compressed head gasket thickness.
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