Educate me on quench

I read in some posts people mentioning "quench." What is it, what is a "tight" quench? How does it affect the way a engine runs?

Quenchis the distance between the flat sides of the combustion chamber and the pistion. Generaly it's only real benifit is in octane challenged builds.

I think the name is kind of misleading, it happens when the flat part of the piston and the flat part of the head come very close together as Dave said. This forces the fuel mixture over into the combustion chamber extremely fast (I have read that there is a sonic boom!). This mixes the air/fuel and allows a more complete burn. You apparently can get away with .5 to 1 point more compression ratio with a tight quench. It is supposed to gain more torque as well.

Bill

"Quench" is exactly what it says. Its main benefit is that it COOLS the charge in the cylinder by squeezing it into close quarters so, it gets maximum cooling from the cylinder head face. Ignition has already begun BEFORE the piston actually gets to the top of the cylinder.
As CLOSE as you can run the piston to the head with minimal clearance, (without actually touching the head), the greater the resistance to detonation.
As a secondary function it DOES create extra turbulence within the chamber to help with completing atomization of the air/fuel charge in order to disipate any hot spots caused from incomplete vaporization.

Quench, or squish area is typically the flat area on the top of the piston that's almost level with the top of the block deck. It must have a corresponding flat area on the deck surface of the head to qualify as quench.
If you look at a combustion chamber, you will usually see these flat areas, and they will have the volume of the actual combustion chamber between them. When the piston is compressing the mixture, as the piston nears the head, the flat areas on the head and piston come together and force the mixture from those areas to "squish" into the chamber, where the spark plug and burning mixture reside, so you achieve a more complete burn.
The quench area also runs cooler than the rest of the chamber / piston. These lower temperatures are where the "quench" comes from.
When properly designed, the quench areas can have a tremendous effect on the quality of combustion, and allow higher compression ratios, and due to this they are considered "artificial octane" by scientific types.
Bottom line is "properly designed, quench is good".

What is a good quench to have on a 13:1 compression N/A motor?

Depends on the Bore Size, but Big Blocks Tend to like .045ish (Bigger Bores) and Smaller Motors Under 4.125 Bore can tend to get away with .035. It also depends on with type of rods you run, Aluminum ones need some extra clearance for growth and strech.

Thats are General Specs, Sometime's they can vary.

4340 h beam scat rods, .030 over bore, I wanted to make sure before we cut my block, I figure a .045 gasket with a 0 deck would be ideal then. I called B.F. evans today and was told a bigger gasket bore would help with valve shrouding, I.E. a 4.6 or a 4.685 bore.

As long as the gasket doesn't protrude into the bore it won't shroud anything.

.045 is fine IMO

Tennessee Bullitt wrote:4340 h beam scat rods, .030 over bore, I wanted to make sure before we cut my block, I figure a .045 gasket with a 0 deck would be ideal then. I called B.F. evans today and was told a bigger gasket bore would help with valve shrouding, I.E. a 4.6 or a 4.685 bore.

It's bigger cyl bore . There is no .045" gasket other than the Cometic stuff. The A441/1018 gaskets are about .041" compressed .
On a non-pump gas engine I'm not sure why one would over deck the block to have the ZERO thing . With 13/1 .045" with your bore is fine and .044" or .047" would work also .

Thanks for setting me straight Lem. I didn't put the grammar right in my last statement...... I rode the short bus to school.

Quench is what happened to my butt when I drove Blake's car at Bowling Green. ---RED

No, that's "Grommet cinch". Or, pucker.