Flat Top Pistons
Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
You can get it yourself using that online calculator :
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
You can get it yourself using that online calculator :
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
, sorry to copy off of your homework. Cylinder Bore Size
Piston Stroke Length
Head Gasket Bore Diameter
Compressed Head Gasket Thickness
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
Now if you have 70 cc heads on it, you've obviously replaced them, which means you replaced the head gaskets. So there's no way we can tell you what your head gasket bore diameter or thickness is. You could take a conservative approach and say your gasket diameter is 4.060" and your thickness is 0.041". That should give you the lowest compression ratio you could expect from your motor. To see your max, use a 4.000" diameter and a 0.015" thickness.
You probably want stock deck height: 0.025".
Last edited by LeMans Pete; Nov 3, 2008 at 06:55 PM.
Thread Starter
Instructor
Joined: Jan 2007
Posts: 233
Likes: 41
From: Simpsonville SC
Thanks, stingr69. I have seen other references of 5cc's for L-82 flat tops but no actual detailed specifications. All I could find was,
TRW L2417
Gm Part Number 474190
350
9:1
76cc
336747,
464664 or
464692
71-80 L-82. Piston OD 3.998 to 3.999".
But no valve relief info..
TRW L2417
Gm Part Number 474190
350
9:1
76cc
336747,
464664 or
464692
71-80 L-82. Piston OD 3.998 to 3.999".
But no valve relief info..
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
L2417F is replacement for L82 piston.
My sealed power cat shows these specs for L2417F
flattop w/ single trough
dome volume: -3.4cc
compression distance: 1.560"
sealed power (Federal Mogul aka TRW) has a static compression ratio calculator that's quite accurate & handy:
http://www.21cgt.com/FMWebCatalog/frmConversion4.aspx
btw ... thin steel shim gasket fp1094 volume = 3.2cc x 0.015" thick.
gm comp gasket 10105117 volume 5.8cc x 0.028".
My sealed power cat shows these specs for L2417F
flattop w/ single trough
dome volume: -3.4cc
compression distance: 1.560"
sealed power (Federal Mogul aka TRW) has a static compression ratio calculator that's quite accurate & handy:
http://www.21cgt.com/FMWebCatalog/frmConversion4.aspx
btw ... thin steel shim gasket fp1094 volume = 3.2cc x 0.015" thick.
gm comp gasket 10105117 volume 5.8cc x 0.028".
Last edited by jackson; Nov 3, 2008 at 11:01 PM.
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Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Unless you have had the block worked at all you have the stock 350 specs: 4.000" bore, 3.48" stroke.
Now if you have 70 cc heads on it, you've obviously replaced them, which means you replaced the head gaskets. So there's no way we can tell you what your head gasket bore diameter or thickness is. You could take a conservative approach and say your gasket diameter is 4.060" and your thickness is 0.041". That should give you the lowest compression ratio you could expect from your motor. To see your max, use a 4.000" diameter and a 0.015" thickness.
You probably want stock deck height: 0.025".
Now if you have 70 cc heads on it, you've obviously replaced them, which means you replaced the head gaskets. So there's no way we can tell you what your head gasket bore diameter or thickness is. You could take a conservative approach and say your gasket diameter is 4.060" and your thickness is 0.041". That should give you the lowest compression ratio you could expect from your motor. To see your max, use a 4.000" diameter and a 0.015" thickness.
You probably want stock deck height: 0.025".
Thanks for the education. 
Racer
Joined: Oct 2006
Posts: 412
Likes: 1
From: St. John's Newfoundland
You can get it yourself using that online calculator :
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
http://www.csgnetwork.com/compcalc.html
That way you can tinker with the best suited head volume/piston compression volume.
That is so cool. I'm working on building my 383 -12 cc dish pistons, 64 cc heads. It's cool to see how you can regulate your cr by either changing your head gasket thickness, shaving you block etc.
Thanks guys
Clyde
