Fly Cutting Piston Reliefs
#875278
12/08/10 09:57 PM
12/08/10 09:57 PM
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Joined: Jan 2003
Posts: 1,221
Jarrettsville, MD
tywebb2
OP
super gas
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OP
super gas
Joined: Jan 2003
Posts: 1,221
Jarrettsville, MD
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I am debating whether to fly cut the reliefs in my TRW 2355 6pak pistons to free up some more ptv clearance. The larger intake valve on the Eddy head is my main concern. Right now I have .120" clearance and I would like to shave my heads for more compression.
If I were to have the valve reliefs opened up would it be as simple as enlarging what is currently there or do the Eddy valves come at the piston at a different angle than the valves in the stock heads? I am just wondering how complicated this would be to do right if I do decide to pull the pistons?
'72 440 Cuda
11.673 @ 115.91 w/1.663 60'
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Re: Fly Cutting Piston Reliefs
[Re: tywebb2]
#875279
12/08/10 10:12 PM
12/08/10 10:12 PM
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Joined: Feb 2007
Posts: 6,295
U.S.
moparniac
master
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master
Joined: Feb 2007
Posts: 6,295
U.S.
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dont have a pics of the tool but what you can do is raise the piston to TDC and put a valve stem with a fine point (machined center obviously)(the tool) in the valve guide in the head and "knock" it into the piston to give a valve center location and give piston to machine shop... or use an in head piston cutter  maybe a pro here will give ya a better advice or technique...
Mopar Performance
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Re: Fly Cutting Piston Reliefs
[Re: tywebb2]
#875280
12/09/10 12:08 AM
12/09/10 12:08 AM
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Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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edelbrock heads use the same valve angle as factory heads. just clay the piston, roll the motor over to make an impression and hand it to your machinist. if they just need to be deeper then don't bother with all tht, but if they need to be enlarged and deeper, use the clay, it's idiot proof.
machine shop owner and engine builder
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Re: Fly Cutting Piston Reliefs
[Re: Performance Only]
#875281
12/09/10 11:13 AM
12/09/10 11:13 AM
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Joined: May 2004
Posts: 3,210
robin hood country
deaks
master
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master
Joined: May 2004
Posts: 3,210
robin hood country
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As i said on the other thread, i used a crane R280 roller with those pistons, with shims and 76cc edelbrock heads and 1.5 rockers to 7000 rpm.
I clayed them first on every cylinder and there was adequate clearance but not enough to advance the cam. My pistons measure .018 below deck.
What cam are you looking to use and has the block been decked.
Hope this helps
Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200#
best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft
best 60ft 1.36
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Re: Fly Cutting Piston Reliefs
[Re: Dodgem]
#875283
12/09/10 07:42 PM
12/09/10 07:42 PM
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Joined: Jan 2003
Posts: 1,221
Jarrettsville, MD
tywebb2
OP
super gas
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OP
super gas
Joined: Jan 2003
Posts: 1,221
Jarrettsville, MD
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Alright....I'll give it a try. My plan is to pull the heads and then bolt them down without the head gasket to check ptv with clay on top of the pistons. That way I can check to see if the intake valve is even sitting down in the valve notch in the piston or not.
'72 440 Cuda
11.673 @ 115.91 w/1.663 60'
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Re: Fly Cutting Piston Reliefs
[Re: tywebb2]
#875286
12/19/10 02:58 PM
12/19/10 02:58 PM
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Joined: Oct 2007
Posts: 4,226
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,226
New York
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The clay method is excellent because the valve opens in 2 planes, and the head will plow the clay aside to follow the actual motion path:
1. deeper as it lifts
2. across the dome due to the stem angle
In a wedge, the "across" motion is small, generally enough that the usual safety margin (OD + .100" etc. includes it.
In a hemi, the scrub across is quite significant, and simply adding depth leaves you with less safety toward the dome center than you think you have.
Boffin Emeritus
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Re: Fly Cutting Piston Reliefs
[Re: John_Kunkel]
#875289
12/19/10 05:15 PM
12/19/10 05:15 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Tell the machine shop to use a cutter that measures .100 larger than the valve your cutting. 
So, nobody uses the old "tool bit brazed to a valve" homemade in place cutter anymore? A good way to be sure the cutter is in the correct position is to do the cutting from the actual valve guide that will be above the piston.
I've done that years ago, now days I have a mill
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Re: Fly Cutting Piston Reliefs
[Re: tywebb2]
#875290
12/19/10 05:42 PM
12/19/10 05:42 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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This is a pic of a piston in my 408 that I cut the valve reliefs in using a cutter I rented from Hughes engines. Basically it was a section of head with valves in it that had carbide cutters welded to the valve faces. Worked great. You might want to check with them to see if they have something that will work with your application.
Fastest 300
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