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Ideal quench distance #59911 05/19/08 09:31 PM 05/19/08 09:31 PM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Is the number you shoot for .040 with an open chamber iron head? What I got is a flat top piston and my farthest one down is .008 in the hole with a .028 head gasket an .011 on the flat of the head to the small flat area in the chamber of my small block J head. Oh and on the other side pistons are zero with the deck. I just had the shop clean the decks till they were flat is why the difference from on side to the next. The side that is zero now was high from one end to the other and accounts for why a little more was taken of the deck on that side. It was pretty flat just not true with the crank front to back when it left Mopar orignally back in 1967.

Re: Ideal quench distance [Re: mopowergtx] #59912 05/19/08 09:34 PM 05/19/08 09:34 PM
A Anonymous Unregistered
Anonymous Unregistered A	yup .040". BUT with a open chamber head, you'll need a set of "reverse dome" or "quench style" pistons. KB seems to be the master of that.

Re: Ideal quench distance [Re: mopowergtx] #59913 05/19/08 09:57 PM 05/19/08 09:57 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	.035-.040" & the recessed area on open chamber heads varies in slope & needs to be machined flat to get it "right",that & KB pistons as mentioned which will also need the dome to be machined makes getting quench on an open chamber headed engine more $$$$ but an engine without proper quench isn't efficient & definitely more prone to ping & you're leaving power on the table. I'm .110 in the hole on mine(SB) & I am going to get it with .050 undersize rod bearings & some deck milling. live every 24 hour block of time like it's your last day on earth

Re: Ideal quench distance #59914 05/20/08 12:06 AM 05/20/08 12:06 AM
A Anonymous Unregistered
Anonymous Unregistered A	Would less be better as far as power ?

Re: Ideal quench distance #59915 05/20/08 01:33 AM 05/20/08 01:33 AM
Joined: May 2008 Posts: 5,399 Aurora, Colorado 451Mopar master
451Mopar master Joined: May 2008 Posts: 5,399 Aurora, Colorado	What are you building? I did a 360 with the KB "Quench" pistons, and it takes alot of extra machining and checking to set-up the quench correctly. I think only a dyno could tell if there is any extra power to be had? The quench is really supposed to help prevent detonation when running junk gas with higher compression ratios. If I did the same 360 over, I would just use a flat top piston. The easiest way to build a Quench engine is to use flat-top pistons and aftermarket aluminum heads that do not have the dished chamber. Ideal quench distance is as close to zero when the engine is running at max RPM without the piston hitting the head. 0.040" is a consertive number, but much larger, like 0.060" and you start to loose the quench effect.

Re: Ideal quench distance [Re: mopowergtx] #59916 05/20/08 07:50 AM 05/20/08 07:50 AM
Joined: Jan 2003 Posts: 74,948 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 74,948 U.S.S.A.	Quote: Is the number you shoot for .040 with an open chamber iron head? What I got is a flat top piston and my farthest one down is .008 in the hole with a .028 head gasket an .011 on the flat of the head to the small flat area in the chamber of my small block J head. Oh and on the other side pistons are zero with the deck. I just had the shop clean the decks till they were flat is why the difference from on side to the next. The side that is zero now was high from one end to the other and accounts for why a little more was taken of the deck on that side. It was pretty flat just not true with the crank front to back when it left Mopar orignally back in 1967. am i reading this correctly ??? one bank of pistons is .008 in the hole and the other side is at zero ??? how are you measuring it ? with feeler blades or a deck bridge and a dial indicator ?

Re: Ideal quench distance [Re: 451Mopar] #59917 05/20/08 10:24 AM 05/20/08 10:24 AM
Joined: Aug 2004 Posts: 1,047 Arizona 6 68CoronetRT super stock
68CoronetRT super stock 6 Joined: Aug 2004 Posts: 1,047 Arizona	Quote: . . . Ideal quench distance is as close to zero when the engine is running at max RPM without the piston hitting the head. . . The danger in trying to get too close is the tolerance factor. Every part i.e. crank, rods, pistons, valves, etc. all have some degree of variation in their movement. If each of the parts named above has say +/- .001 tolerance there is a cumulative +/- .004 amount of movement potential. There is also the expansion due to heat and the stress of high rpms that can introduce even more movement. Hence, the .035-.040 quench range gives you the desired affect of reducing detonation as well as improving power while not endangering your engine. As stated earlier the easiest way to achieve this is with flat top pistons at zero deck and after market closed chamber heads using a .039" head gasket.

Re: Ideal quench distance [Re: JohnRR] #59918 05/20/08 11:41 AM 05/20/08 11:41 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Quote: Quote: Is the number you shoot for .040 with an open chamber iron head? What I got is a flat top piston and my farthest one down is .008 in the hole with a .028 head gasket an .011 on the flat of the head to the small flat area in the chamber of my small block J head. Oh and on the other side pistons are zero with the deck. I just had the shop clean the decks till they were flat is why the difference from on side to the next. The side that is zero now was high from one end to the other and accounts for why a little more was taken of the deck on that side. It was pretty flat just not true with the crank front to back when it left Mopar orignally back in 1967. am i reading this correctly ??? one bank of pistons is .008 in the hole and the other side is at zero ??? how are you measuring it ? with feeler blades or a deck bridge and a dial indicator ? dial indicator, and before you say how bad that is remember this was a running motor that left Chrysler in 1967 with the pistons almost .020 difference in the hole front to back on the one bank. .008 on one side and zero on the other looks bad on paper but theres no way its going to cause me a problem if factory tolerance would allow for .020 front to back on the same bank. .008 is a whisp compared to that. Especially when you figure my head gaskets are spec'ed at .024 to .028 compressed thickness. The gaskets could have a .004 tolerance between them for that matter. You cant evan see the .008 with the eye I have to run a finger acrossed it to know that its down in the hole at all on that side. Last edited by mopowergtx; 05/20/08 11:51 AM.

Re: Ideal quench distance [Re: 68CoronetRT] #59919 05/20/08 11:41 AM 05/20/08 11:41 AM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	I have also always heard, .040 is ideal. .035 is pushing it because your clearances are getting pretty close by then. By the time you hit .060 quench effect is pretty much nil. It's a very short range to be effective and safe. With open chamber heads, you have to run quench dome pistons and a lot of careful machining to get everything just right. I would not bother unless you are running closed chamber heads. That way you can run a flat top piston and just worry about deck milling to get everything lined up right. I wouldn't bank on getting a noticeable increase in power with a quench setup, it's more for detonation prevention. Allows you to run more compression on crap gas. Also quench setups require less ignition timing to get the job done properly, so that also helps with the detonation situation.

Re: Ideal quench distance [Re: DaytonaTurbo] #59920 05/20/08 11:54 AM 05/20/08 11:54 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Like I said they are J's and they are flat tops so Im just measuring the small flat spot on the chamber to make sure I'm a safe distance between it and the piston top I guess.

Re: Ideal quench distance [Re: mopowergtx] #59921 05/20/08 01:50 PM 05/20/08 01:50 PM
Joined: Dec 2004 Posts: 1,061 New Mexico D dmerc super stock
dmerc super stock D Joined: Dec 2004 Posts: 1,061 New Mexico	I'm running .031 quench on my tallest piston. This on a 408 stroker that doesn't rev past 5000 rpm. They all vary a few thousanths but I have seen no evidence that there is any problem.

Re: Ideal quench distance [Re: dmerc] #59922 05/20/08 01:55 PM 05/20/08 01:55 PM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Quote: I'm running .031 quench on my tallest piston. This on a 408 stroker that doesn't rev past 5000 rpm. They all vary a few thousanths but I have seen no evidence that there is any problem. I plan to spin this one to 6500 so I kinda wanted to make sure I wasnt getting to close to the head.

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