I need to vent Quench vs piston to wall clearance

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I need to vent Quench vs piston to wall clearance

Post  Imtruckinup on December 6th 2012, 10:34 pm

Blocks coming home from machine shop in a couple days ...This is all on paper theory. My minds going a mile a minute right now. Long story short as the title says quench vs PTW clearance. Scat cast crank 4.3 stroke .003 bearing...scat 4340 6.8 h rod .002 bearing ....forged kaase dish probe piston 30 over. 4-5 out of the hole and 4 piston to wall Thinking of running a .040 cosmetic head gasket to keep my quench fairly tight .035.... At .004 piston to wall.....
how much do you think the piston will rock . Do you think I will kiss the head

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Re: I need to vent Quench vs piston to wall clearance

Post  dfree383 on December 7th 2012, 2:53 am

Better loosen it up to about .045 or so IMO.
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Re: I need to vent Quench vs piston to wall clearance

Post  Imtruckinup on December 7th 2012, 7:52 am

I f orgot to put in there that it will only be spun to around 5500. Does the 45 quench still hold

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Re: I need to vent Quench vs piston to wall clearance

Post  dfree383 on December 7th 2012, 11:08 am

Yes.
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Re: I need to vent Quench vs piston to wall clearance

Post  IDT-572 on December 7th 2012, 5:30 pm

I ran my 557 at .0375 with .006 piston to wall and it barley touched after i spun it to 75+ a couple of times. But it had good parts in it.

I ran a 2300 Ford OHV engine at .030 with .005 PTW at 8000 RPM on a 1/4 mile dirt track, but it was a light piston and a long rod deal. And I did this over a four year time span sneaking up on it every year. Anything tighter or if the engine temp got high and it would dust the carbon off the piston tops.

I usually run .041 0 deck and .041 gasket with no problem.
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Re: I need to vent Quench vs piston to wall clearance

Post  Imtruckinup on December 7th 2012, 8:25 pm

Yea I've been talking a lot with people on 460 ford about it... I think there's a lot of good info coming from em
Scotty over there fromRHP has put my mind to ease with most of it as I will change my setup around a little bit I think it's a pretty good read if interested... Engine tech and it is the same tittle ...I'd like to thank you Blake as you have answered some of my questions before and I appreciate your time and knowledge

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Re: I need to vent Quench vs piston to wall clearance

Post  Lem Evans on December 7th 2012, 10:03 pm

Imtruckinup wrote:Blocks coming home from machine shop in a couple days ...This is all on paper theory. My minds going a mile a minute right now. Long story short as the title says quench vs PTW clearance. Scat cast crank 4.3 stroke .003 bearing...scat 4340 6.8 h rod .002 bearing ....forged kaase dish probe piston 30 over. 4-5 out of the hole and 4 piston to wall Thinking of running a .040 cosmetic head gasket to keep my quench fairly tight .035.... At .004 piston to wall.....
how much do you think the piston will rock . Do you think I will kiss the head

Your .002" at the rod bearing is too tight.

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Re: I need to vent Quench vs piston to wall clearance

Post  kim on December 7th 2012, 10:32 pm

I have oliver rods, billet crank, JE ultralight pistons. .005 skirt clearance, .004 main clearance, 6.8 rod, 3.900 stroke. the pistons come .005 out the hole, and have .037" thick crush copper head gaskets.

At 9600 RPM the quench area of the piston has not tapped the head. Now the hand matched combustion chamber to dome had a couple little ding areas. But nothing a wire wheel couldn't knock off the piston top.

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Re: I need to vent Quench vs piston to wall clearance

Post  Lem Evans on December 8th 2012, 12:05 am

kim wrote:I have oliver rods, billet crank, JE ultralight pistons. .005 skirt clearance, .004 main clearance, 6.8 rod, 3.900 stroke. the pistons come .005 out the hole, and have .037" thick crush copper head gaskets.

At 9600 RPM the quench area of the piston has not tapped the head. Now the hand matched combustion chamber to dome had a couple little ding areas. But nothing a wire wheel couldn't knock off the piston top.

Try that with the short pistons that come with the 4.500"-4.750" strokes and report back.....it's a much different world.

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