Deck height, compression ratio, and valve relief flat top pistons, In a 2.0 |
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Deck height, compression ratio, and valve relief flat top pistons, In a 2.0 |
emerygt350 |
Jul 13 2023, 11:41 AM
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#1
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Advanced Member Group: Members Posts: 2,144 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Ok, my question of the day:
Put my new 96mm pistons and cylinders on and measured deck height, .033 all the way around. Let's say .032 to be conservative. I will not be running head gaskets. The calculator gives me 8.8 CR at .033 8.6 CR at .043 8.4 CR at .053 The pistons have a valve relief (pretty large) cut. I am shooting for 8.4 CR. Heads are in the shop so I can't check the CC yet. Everything I read says .04 - .06 for deck height. With the valve relief do I need to worry about going lower? If I had dishes would you measure from the edge of the piston or the dish? |
Jack Standz |
Jul 13 2023, 01:53 PM
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#2
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Member Group: Members Posts: 281 Joined: 15-November 19 From: Happy Place (& surrounding area) Member No.: 23,644 Region Association: None |
For what it's worth, our 2056 had pistons with valve reliefs that cc'd at 3 CCs per the manufacturer's specifications and real world measurements.
Also, I'd still check the valve to piston clearance as you wouldn't want them to hit. There are ways to end up with inadequate clearance, like the pistons are upside down or what's the actual valve lift, etc. Mock them up and measure a few times, use some play dough. Then order the spacers and re-measure when you get them. |
emerygt350 |
Jul 13 2023, 02:19 PM
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#3
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Advanced Member Group: Members Posts: 2,144 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
For what it's worth, our 2056 had pistons with valve reliefs that cc'd at 3 CCs per the manufacturer's specifications and real world measurements. Also, I'd still check the valve to piston clearance as you wouldn't want them to hit. There are ways to end up with inadequate clearance, like the pistons are upside down or what's the actual valve lift, etc. Mock them up and measure a few times, use some play dough. Then order the spacers and re-measure when you get them. That's what I was thinking. I want to check the valve geometry so I will be putting it together to test that with full intent to tear down again. That valve relief is what is going to make for issues I think. |
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