bore and stroke
Posting Guru
Joined: Jul 2003
Posts: 2,232
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From: Colville, Washington
bore and stroke
It doesn't matter which cylinder you measure, but the bore is simply the diameter of the cylinder. The stroke is how far the piston moves up and down in the cylinder. A rough size can be measured with a dial caliper, the head needs to be removed to accurately measure.
Posting Guru
Joined: Jul 2003
Posts: 2,232
Likes: 1
From: Colville, Washington
bore and stroke
There is a displacement tool they use in racing, but unless you've got friends in NASCAR or NHRA you probably won't find one. I don't know of any way to measure the bore and stroke without pulling the head. Ideas, anyone???
Senior User
Joined: Jun 2003
Posts: 107
Likes: 0
From: Allentown, PA
bore and stroke
R35,
If you want the exact bore and stroke, the other guys are correct that you will need to pull a head.
If your simply looking for displacement you can probably make some sort of crude tool out of an old spark plug, a rubber hose, a clear plastic bottle (like a 2 liter soda bottle) and some motor oil.
Simply crank the engine over until the cylinder you are trying to measure is at TDC. With the soda bottle connected to the hose, and the other end of the hose connected to the metal end of an old spark plug (guts removed from the plug) add oil to the soda bottle until it reaches some convenient level. Mark this point precisely. Now crank the engine over until the piston is at BDC and using a measuring cup from the kitchen pour in enough oil to bring the level back up to the mark you made when the piston was at TDC. Be sure you get all the air out and the valves are closed when you do this. You will now know how much the displacement is in ounce’s, which can then be converted to cubic inches. I believe that's the basic process that is used by racing org's to verify a competitor’s engine displacement.
Here’s a good site for performing engine calculations. You do have to register to use it though. http://www.smokemup.com/auto_math/index.php
Good luck!
If you want the exact bore and stroke, the other guys are correct that you will need to pull a head.
If your simply looking for displacement you can probably make some sort of crude tool out of an old spark plug, a rubber hose, a clear plastic bottle (like a 2 liter soda bottle) and some motor oil.
Simply crank the engine over until the cylinder you are trying to measure is at TDC. With the soda bottle connected to the hose, and the other end of the hose connected to the metal end of an old spark plug (guts removed from the plug) add oil to the soda bottle until it reaches some convenient level. Mark this point precisely. Now crank the engine over until the piston is at BDC and using a measuring cup from the kitchen pour in enough oil to bring the level back up to the mark you made when the piston was at TDC. Be sure you get all the air out and the valves are closed when you do this. You will now know how much the displacement is in ounce’s, which can then be converted to cubic inches. I believe that's the basic process that is used by racing org's to verify a competitor’s engine displacement.
Here’s a good site for performing engine calculations. You do have to register to use it though. http://www.smokemup.com/auto_math/index.php
Good luck!
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