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Anybody stack head gaskets for quench

Regardless of what you do, a good rule of thumb is to have .040" clearance between the piston and anything it might hit. So if the piston is .010" out of the hole, the OP should use .050" head gaskets.
That's being super safe which isn't a bad thing.....but, I'll go with .030 with steel rods any day of the week and have done one that was even closer. The dirt track guys will do that too but only with a short stroke and steel rods.
 
I need about .040 for a better quench. I'm to close now. I have an extra set of fel-pro that will raise the quench to a tolerable clearance. I am cheap too, so having said that I could stack the gaskets and that would work and save me some cash. I don't want to spend big money on a pair of gaskets if I don't have to
Anybody do this?

Doesn't adding head gasket thickness REDUCE the available quench area (moves the head away from piston at TDC) ?? AND in additional consideration, will the "new" head installed location, affect the intake manifold to the head interface dimension, resulting in potential leak areas? Just asking........
BOB RENTON
 
Bob, the thicker head gaskets increase the distance between the block deck, piston top to the cylinder head. This increases the quench area and reduces the compression ratio at the same time. Some engines in the 70s to 80s hardly had any quench since the compression was so low. On the other hand the 915 heads have a closed chamber which gives them a nice quench area using the proper piston and gasket.
 
Bob, the thicker head gaskets increase the distance between the block deck, piston top to the cylinder head. This increases the quench area and reduces the compression ratio at the same time. Some engines in the 70s to 80s hardly had any quench since the compression was so low. On the other hand the 915 heads have a closed chamber which gives them a nice quench area using the proper piston and gasket.

Thanx for the explanation.....I thought (incorrectly) that the quench area of the combustion chamber is the area presented as the piston is at TDC and is at the closest to the head surface, as you noted in the 915 closed chamber heads. This quench area functioned to squeeze or squirt the compressed fuel charge toward the spark plug and to provide a turbulent area to insure more or better combustion. However, the quench area allowed dead space for un-burned HC to accumulate which lead to the development of the open chamber 906 heads, appearing in the 1968 + models, in an effort reduce emissions. I guess it comes down to semantics as to the definition of the term "quench area" as it applies to engine design......
BOB RENTON
 
Yep. And, if the motor is out of the car, you could do it yourself at home for probably the cost of the second set of gaskets. Actually, you might be able to do it in the car.

The quench dome foot print is not that large either, so I don't think the out of balance would be an issue. Could be wrong.
This ^^^^^^
 
The balance won't be affected enough to worry about.
Doug
 
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