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Minimum quench ? #1361024
12/29/12 06:05 PM 12/29/12 06:05 PM
Joined: May 2004
Posts: 1,522
Ste-Sophie, Quebec, Canada
W
Wedgeman Offline OP
pro stock
Wedgeman  Offline OP
pro stock
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Joined: May 2004
Posts: 1,522
Ste-Sophie, Quebec, Canada
What would be the minimum clearance between piston and head ? is .019 too little using H beam scat rods ?

Dan
Re: Minimum quench ? [Re: Wedgeman] #1361025
12/29/12 06:14 PM 12/29/12 06:14 PM
Joined: Aug 2011
Posts: 2,913
Pattison Texas
CSK Offline
master
CSK  Offline
master

Joined: Aug 2011
Posts: 2,913
Pattison Texas
need .040

1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5
Re: Minimum quench ? [Re: Wedgeman] #1361026
12/29/12 07:31 PM 12/29/12 07:31 PM
Joined: Jan 2007
Posts: 3,695
nc
E
emarine01 Offline
master
emarine01  Offline
master
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Joined: Jan 2007
Posts: 3,695
nc
Quote:

What would be the minimum clearance between piston and head ? is .019 too little using H beam scat rods ?

Dan

Thats about .010 too close

Re: Minimum quench ? [Re: CSK] #1361027
12/29/12 07:59 PM 12/29/12 07:59 PM
Joined: Jul 2012
Posts: 434
Washington
skrews Offline
mopar
skrews  Offline
mopar

Joined: Jul 2012
Posts: 434
Washington
.040

Last edited by skrews; 12/29/12 08:00 PM.
Re: Minimum quench ? [Re: Wedgeman] #1361028
12/29/12 08:17 PM 12/29/12 08:17 PM
Joined: Aug 2003
Posts: 43,882
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
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Joined: Aug 2003
Posts: 43,882
Bend,OR USA
Quote:

What would be the minimum clearance between piston and head ? is .019 too little using H beam scat rods ?

Dan

Probally to close What psiton type and materials are yours and how much piston to cylinder wall do you have now? My pump gas 518 C.I. stroker with .0065 piston to cylinder wall clearance was rocking over enough to make it look like it was hitting the edge of the pistons on the combustion chamber edges when warmed up (190F) and revved up above 7000 RPM with .035 cold checking clearances( make sure and rock the piston all the way to the outside of the block and the same on the inside(cam side) I increased the head gasket thickness .008 to get .043 minimum I was trying to follow the recommendations of using .035 with steel rods and forged pistons That worked fine on the iron, open chamber 906 heads, not so good when I swapped the heads to a set of close chamber Eddy RPM aluminum heads

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Minimum quench ? [Re: skrews] #1361029
12/29/12 08:18 PM 12/29/12 08:18 PM
Joined: Jan 2010
Posts: 1,186
st.cloud fl
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d-150 Offline
Smarter than a 5th grader?
d-150  Offline
Smarter than a 5th grader?
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Joined: Jan 2010
Posts: 1,186
st.cloud fl
just use head gasket to make up difference .036 minimum but .040 optimum
Re: Minimum quench ? [Re: Wedgeman] #1361030
12/29/12 08:55 PM 12/29/12 08:55 PM
Joined: Jan 2003
Posts: 75,324
A gulag near you.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 75,324
A gulag near you.
way too close , you want to get as close to .040 as possible
Re: Minimum quench ? [Re: Wedgeman] #1361031
12/29/12 09:41 PM 12/29/12 09:41 PM
Joined: Nov 2004
Posts: 1,708
S. Il. U.S.A.
5spdcuda Offline
top fuel
5spdcuda  Offline
top fuel

Joined: Nov 2004
Posts: 1,708
S. Il. U.S.A.
I've run .038 on a 4.030 bore with .0025 piston to wall and stock rods with no problems. At .035 I would get nervous.
Re: Minimum quench ? [Re: CSK] #1361032
12/29/12 10:37 PM 12/29/12 10:37 PM
Joined: Feb 2005
Posts: 4,333
Prospect, PA
BSB67 Offline
master
BSB67  Offline
master

Joined: Feb 2005
Posts: 4,333
Prospect, PA
Quote:

need .040



Really.
Re: Minimum quench ? [Re: 5spdcuda] #1361033
12/29/12 10:38 PM 12/29/12 10:38 PM
Joined: Jan 2007
Posts: 3,695
nc
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emarine01 Offline
master
emarine01  Offline
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Joined: Jan 2007
Posts: 3,695
nc
We ran .032 on 4.030 bore cast piston stock rod with .004 skirt cl to 7k and never hit with W2 econos open chamber, some have posted .028 on a tight small block, The quench effect will fall off rapidly after .040.
Re: Minimum quench ? [Re: 5spdcuda] #1361034
12/29/12 10:39 PM 12/29/12 10:39 PM
Joined: Jan 2003
Posts: 6,415
nielsville, minn.
Q
quickd100 Offline
master
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Q

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Posts: 6,415
nielsville, minn.
I set up a 440 with KB hyerutectic's at .035. Mild hydralic cam, steel rods, never see's 6000rpm. Works great but was a pain in the butt setting the quench distance that close.Dave
Re: Minimum quench ? [Re: 5spdcuda] #1361035
12/29/12 10:47 PM 12/29/12 10:47 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
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Posts: 52,972
Romeo MI
Quote:

I've run .038 on a 4.030 bore with .0025 piston to wall and stock rods with no problems. At .035 I would get nervous.



I ran .032 on a 4.070 bore and it just touched at 8000 rpm
in one spot... I hit it with a die grinder on the heads
and it was fine
Re: Minimum quench ? [Re: MR_P_BODY] #1361036
12/29/12 10:57 PM 12/29/12 10:57 PM
Joined: May 2004
Posts: 1,522
Ste-Sophie, Quebec, Canada
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Wedgeman Offline OP
pro stock
Wedgeman  Offline OP
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Joined: May 2004
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Ste-Sophie, Quebec, Canada
Ok

Thanks for all the responses !

Dan
Re: Minimum quench ? [Re: MR_P_BODY] #1361037
12/29/12 11:06 PM 12/29/12 11:06 PM
Joined: Jan 2007
Posts: 3,695
nc
E
emarine01 Offline
master
emarine01  Offline
master
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Joined: Jan 2007
Posts: 3,695
nc
Most of the time a piston strikes the head its from the piston rocking
in the bore, I know this will not sit right with some but if the piston just kisses the head it will just rock back This is not the best thing but I have seen a fellas 383 sbc @ .028 turn 8500 for years with the pistons hitting the head... it just leaves little marks

Re: Minimum quench ? [Re: emarine01] #1361038
12/29/12 11:40 PM 12/29/12 11:40 PM
Joined: May 2006
Posts: 1,260
New Mexico
A
Adobedude Offline
pro stock
Adobedude  Offline
pro stock
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Joined: May 2006
Posts: 1,260
New Mexico
.040 to be safe. As per previous post...Piston rock.

2001 Dodge Dakota
408 All Motor
11.27 @ 117.83 mph
2017 NM Mopar Challenge Series Champion.
Re: Minimum quench ? [Re: Adobedude] #1361039
12/30/12 05:38 AM 12/30/12 05:38 AM
Joined: Nov 2004
Posts: 2,825
Sk. Canada
RemCharger Offline
master
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Posts: 2,825
Sk. Canada
When you can read the piston # on the head its just right.
Re: Minimum quench ? [Re: RemCharger] #1361040
12/31/12 11:44 AM 12/31/12 11:44 AM
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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moper Offline
I Live Here
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I Live Here
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
Quote:

When you can read the piston # on the head its just right.



That's what I always heard for race engines too...
On my street/strip stuff I run .030-.040 depending on the compression hieght and bore size. Tighter is better and with good equipment and operator it's as easy as having the machining operations done.

Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
Re: Minimum quench ? [Re: RemCharger] #1361041
12/31/12 12:36 PM 12/31/12 12:36 PM
Joined: Oct 2007
Posts: 4,219
New York
polyspheric Offline
master
polyspheric  Offline
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Joined: Oct 2007
Posts: 4,219
New York
Guess where the .001" safety clearance you should have had went to?
It's deducted from your top ring land height, if you're lucky.

Boffin Emeritus
Re: Minimum quench ? [Re: polyspheric] #1361042
12/31/12 07:06 PM 12/31/12 07:06 PM
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
dodgeboy11 Offline
super stock
dodgeboy11  Offline
super stock

Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
Depends on the piston type, cylinder clearance, intended rpm and rod type and quality. I'm running .035" on a small block with KB hypereutectic pistons and about .0025" clearance on the skirts. Runs great. I wouldn't be afraid of .030" on that one either. But you start opening up the bore and using forged pistons, you'll want more clearance because of piston rock and growth. I suggest shooting for zero deck and running the quench at whatever your gasket thickness is. On a Fel-Pro it'll typically be .039".
Re: Minimum quench ? [Re: RemCharger] #1361043
01/01/13 12:35 PM 01/01/13 12:35 PM
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
Leon441 Offline
master
Leon441  Offline
master

Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
Quote:

When you can read the piston # on the head its just right.



Yerp, I place marks on my pistons just for this. Run it close as I dare. Then pull the heads and see if I can go some more. Once I know I continue to run that. If I suddenly start seeing marks with the borescope I know there is something wrong.

What you can get away with depends on bore, piston to wall, rods, and what makes you nervous.

Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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