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5.3 with flat top pistons & 706 heads with valve job

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Old 02-12-2012, 04:34 PM
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Default 5.3 with flat top pistons & 706 heads with valve job

Building a 5.3 and thinking about flat top pistons with the stock 706/862 heads. If i get some 2.0 intake valves from say a 317 and have a performance valve job done is this a good plan and what will the CR be?
Old 02-12-2012, 05:11 PM
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Did I hear you say 5.3 with flat top pistons? Compression ratio will be 10.5 , but the bore on this block is oversized so it will not be the same a stock 3.780




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Old 02-12-2012, 06:17 PM
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Approx 10.5 deppending on gaskets and if the deck needs to be cleaned up on the head or block. The 2.0 valves may shroud a little in the stock bore.
You can get 1.95 valve. Or have them turned down. If your really looking to get Max flow use an after market valve thats back cut.

Honestly your best bet is to get a done set of heads through a vendor. You can easily spend $500 on parts and labor with out even getting any port work done.

You can get a nice set of CNC Ported heads Through SDPC. they start at $899 depending on spring option.

If you feel that is to much compresion Use an LS1 Head. they have a larger cumbustion chamber. They will net you around 9:9 -1
Old 02-12-2012, 07:12 PM
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243or799 heads with stock bore flat piston 9.9 ratio

241 heads with stock bore flat pistons 9.8 ratio

706 heads with stock bore flat pistons 10.4 ratio
Old 02-12-2012, 07:17 PM
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I wouldn't be afraid of running a 10.4:1 setup.
Old 02-12-2012, 07:33 PM
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Im gonna find out what 10.5 will do in a Suburban
Old 02-12-2012, 11:33 PM
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Where are those flat top pistons offered? I have only seen the Wiesco pistons with -2 and -7cc offered for the 5.3 (I believe the -2cc gives 10.4:1 compression with stock heads though).
Old 02-12-2012, 11:40 PM
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Originally Posted by 53bowtie
Where are those flat top pistons offered? I have only seen the Wiesco pistons with -2 and -7cc offered for the 5.3 (I believe the -2cc gives 10.4:1 compression with stock heads though).
Came stock on all 4.8s
Old 02-12-2012, 11:41 PM
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Originally Posted by 1FastBrick
Approx 10.5 deppending on gaskets and if the deck needs to be cleaned up on the head or block. The 2.0 valves may shroud a little in the stock bore.
You can get 1.95 valve. Or have them turned down. If your really looking to get Max flow use an after market valve thats back cut.

Honestly your best bet is to get a done set of heads through a vendor. You can easily spend $500 on parts and labor with out even getting any port work done.

You can get a nice set of CNC Ported heads Through SDPC. they start at $899 depending on spring option.

If you feel that is to much compresion Use an LS1 Head. they have a larger cumbustion chamber. They will net you around 9:9 -1


May be an answer I should know but, what do you mean by shrouding?
Old 02-13-2012, 04:41 AM
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Originally Posted by 53bowtie
Where are those flat top pistons offered? I have only seen the Wiesco pistons with -2 and -7cc offered for the 5.3 (I believe the -2cc gives 10.4:1 compression with stock heads though).
Got my pistons from sealer power, speed pro pistons were $35 each.


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