What is Quench

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.050 is where it starts to stop working but still works
but .050 is hard to get with open chamber MOPAR heads without lots of milling, pistons, or AL heads
quench make less difference with high rpm motor and race gas
quench makes bad gas more tolerable and is less sensitive to timing
quench makes less difference to a lightly loaded engine in a light car
it really helps in a heavy vehicle with tall gears
we found it helped just as much in a low compression motor home motor as in a high compression road racer
one of my 440's comes out of the block .010- I just milled the D CUP deeper .030 quench 256 cam works great in Motorhome
 
Wyrmrider said:
not cost prohibitive if you are buying pistons anyway
Click to expand...

Incorrect. It's a total waste of time and money unless you have an entire modern machine shop in your garage. Pistons are less than half of the equation when building for a time effective quench distance... and the available KBs will need trimming once the 2nd or 3rd mock up is complete. All costing time and money. Machining for effective quench with a cast-iron open head, including the mocking up (repeatedly) will run the machining costs up beyond the price of better (some much better w/modern closed chambers) heads. So unless there is a class restriction or a strong personal preference there is no reason to do it. If you can't get the parts within .030-.040 it's not worth doing.
 
only reason to run open chamber heads today is for a matching number restore
I get it right with one test build, which I would do with or without quench pushrod clearance etc
just rebuilding old cast iron costs almost as much as new heads
the reason to do it is that they run so much better
why are we building new motors in the first place
but you gotta remember I helped design those pistons- lots of dyno time in them and the forged predecessors
but I'm not prejudiced- no not much
 
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