Quench?
Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
RE: Quench?
Go here for a good explanation of how to set quench.
https://www.hdforums.com/m_246220/tm.htm
If you had zero deck height, meaning the piston at TDC was even with the top of the cylinder when the base gasket has been compressed using specified torque and you bolted the head on with no gaskets, you would have zero quench. If you have zero deck height and you had a .045 head gasket when compressed at specified torque, you would have .045 quench. Quench is a measurement of plus or minus deck height andhead gasket thickness when compressed. Optimum quench is .030 up to a max of .035, which allows a faster flame front, more complete combustion and less susceptability to pinging and less ignition advance.
https://www.hdforums.com/m_246220/tm.htm
If you had zero deck height, meaning the piston at TDC was even with the top of the cylinder when the base gasket has been compressed using specified torque and you bolted the head on with no gaskets, you would have zero quench. If you have zero deck height and you had a .045 head gasket when compressed at specified torque, you would have .045 quench. Quench is a measurement of plus or minus deck height andhead gasket thickness when compressed. Optimum quench is .030 up to a max of .035, which allows a faster flame front, more complete combustion and less susceptability to pinging and less ignition advance.
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Joined: Oct 2007
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Likes: 15
RE: Quench?
after you are done you tip a cold one and quench your thirst and toast your accomplishment.
It is the area that the flame front travels bewteen the pistons and sides of the combustion chambers (the outside edge of pistons and heads) Ideally you want this to be .030 to insure a clean burn with max power and less chance of pinging. If the squish/quench is to much the flame can hide and you then you can have two flame fronts that hit each other (detonation)
It is the area that the flame front travels bewteen the pistons and sides of the combustion chambers (the outside edge of pistons and heads) Ideally you want this to be .030 to insure a clean burn with max power and less chance of pinging. If the squish/quench is to much the flame can hide and you then you can have two flame fronts that hit each other (detonation)
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Tourer
Joined: Jan 2005
Posts: 477
Likes: 3
From: Jacksonville, Fla
RE: Quench?
Good explanation guys...so lets see?
I'm installing new SE 1550 pistons with a new set of bored out jugs. Will I still need to measure the OLD deck height?
If you have negative deck heightthen you must remove material from the bottom of the cylinders.
If you have positive deck height how is this corrected? Gasket shims?
I'm installing new SE 1550 pistons with a new set of bored out jugs. Will I still need to measure the OLD deck height?
If you have negative deck heightthen you must remove material from the bottom of the cylinders.
If you have positive deck height how is this corrected? Gasket shims?
Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
RE: Quench?
ORIGINAL: fryeca
Good explanation guys...so lets see?
I'm installing new SE 1550 pistons with a new set of bored out jugs. Will I still need to measure the OLD deck height?
If you have negative deck heightthen you must remove material from the bottom of the cylinders.
If you have positive deck height how is this corrected? Gasket shims?
Good explanation guys...so lets see?
I'm installing new SE 1550 pistons with a new set of bored out jugs. Will I still need to measure the OLD deck height?
If you have negative deck heightthen you must remove material from the bottom of the cylinders.
If you have positive deck height how is this corrected? Gasket shims?
If you have negative deck height, you could go with a thinner head gasket up to a point. Say you have .008 negative deck height and a gasket that is .045, your quench would be .053. If you use a Cometic .023 gasket and still have the negative .008, you would end up with quench of .031, ideal.
Positve deck height would just require the opposite, a thicker head gasket to get you where you want to be.
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