Measuring piston to deck height properly
Thread Starter
TECH Apprentice
Joined: Oct 2005
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From: Norwalk, CT
Measuring piston to deck height properly Just wondering if there was a proper procedure to do this. I would assume you have to measure on both sides of the piston (inner/outer) to take into account the piston rock. Do you then take the average of the two measurements and use that figure? Tried a search but could not find any good info.
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From: Norwalk, CT
Originally Posted by SStrokerAce
Depends on the piston to wall clearance. Also you want to check every corner cylinder.
Bret
Bret
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From: Laguna Niguel, CA
Originally Posted by SStrokerAce
Depends on the piston to wall clearance. Also you want to check every corner cylinder.
Bret
Bret
Corner Cylinder sounds kinda funny, like a square peg in a round hole
.Do you mean the cylinders on the front and back of the block, for each bank. Why not just check all the clyinders?
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Originally Posted by fast98
you are supposed to measure on both sides of the piston parrallel to the wrist pin. there should be no piston rock there
There should be very little rock side to side, but these short skirts do make them more prone to rocking top to bottom. I think this may be what Bret meant by check all corners.
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Joined: Jan 2004
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From: Detroit,MI
I check cylinders #1,2,7,and 8. Basically the four corners of the block.
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
Thread Starter
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Joined: Oct 2005
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From: Norwalk, CT
Originally Posted by Uthinkso
I check cylinders #1,2,7,and 8. Basically the four corners of the block.
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
FormerVendor
Joined: Nov 2001
Posts: 3,065
Likes: 6
From: Houston, Tx.
Originally Posted by Uthinkso
I check cylinders #1,2,7,and 8. Basically the four corners of the block.
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
The procedure I use is this.
1-bring piston to TDC
2-use dial indicator and zero it reading off the deck surface
3-move indicator onto piston surface, on either the right or left of the piston
4-from the opposite side of the indicator push down on the piston, and then push down on the side with the indicator
5-Take the two measurements and add them together. For example -10, +7 would put you the piston down .003.
6-You take measurements from both sides and then add the two numbers and divide them by two. Example -.003 on the right and -.005 on the left, together they are -.008 /2 = -.004
Also when you are checking them in and out of the hole by rocking them you need to hold down one side while turning the crank to make sure its breaking over at true TDC and then rock the piston the other way as well also turning the crank to make sure it is breaking over at true TDC. Then average those two and then average each side to see what the overall deck height is.
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Joined: Jan 2004
Posts: 633
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From: Detroit,MI
Originally Posted by racer7088
You've got it right but on number 5 you need to average them instead of adding them up you need to add them up and divide by two just like you did in number 6.
Also when you are checking them in and out of the hole by rocking them you need to hold down one side while turning the crank to make sure its breaking over at true TDC and then rock the piston the other way as well also turning the crank to make sure it is breaking over at true TDC. Then average those two and then average each side to see what the overall deck height is.
Also when you are checking them in and out of the hole by rocking them you need to hold down one side while turning the crank to make sure its breaking over at true TDC and then rock the piston the other way as well also turning the crank to make sure it is breaking over at true TDC. Then average those two and then average each side to see what the overall deck height is.
I guess I'm not following what you mean by spinning the crank as you hold down one side of the piston.
FormerVendor
Joined: Nov 2001
Posts: 3,065
Likes: 6
From: Houston, Tx.
Originally Posted by Uthinkso
By using a dial indicator and verifying the piston is at TDC before you take your measurements, wouldn't that be sufficient.
I guess I'm not following what you mean by spinning the crank as you hold down one side of the piston.
I guess I'm not following what you mean by spinning the crank as you hold down one side of the piston.
Originally Posted by Uthinkso
I check cylinders #1,2,7,and 8. Basically the four corners of the block.
I'm guessing the latter may not be the case, since your method does measure deck clearance on four cylinders, and not just one.
TECH Enthusiast
Joined: Jan 2004
Posts: 633
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From: Detroit,MI
Originally Posted by hammertime
Since you are only checking the front and rear cylinders, aren't you missing the possibilty that the height is higher (less deck clearance) on 3,4,5 & 6 since they are on different crank throws? Or is it safe to assume that blueprint measurments for stroke on each throw will add up the same?
I'm guessing the latter may not be the case, since your method does measure deck clearance on four cylinders, and not just one.
I'm guessing the latter may not be the case, since your method does measure deck clearance on four cylinders, and not just one.
The deck height is checked and verified in the machining process to level and true.
Only reason I check four is for repeatability and being over bearing.
