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#1
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440 6 pack pistons Question
Hello,
I'm new to this forum. I'm building a 440 to swap into my '67 Satellite. I've got a '71 440 block, 452 heads milled .010 and TRW 440 6 pack pistons. Can someone give me a ballpark figure of what my compression ratio will be with this combination? I've been told by a couple people that I may need to have some material taken off the tops of the pistons or the compression ratio will be too high for street use. I'd like to end up with 9.5:1 or so. I realize everything will have to be measured and the heads CC'd to really know what's going on but I thought that this might be a common enough combo that someone here had done it already and could give me some info. Thanks in advance. |
#2
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Not enough info. Need to know if those pistons are dish,flat, or dome. If they have valve notches and the cc of them. Is it 0 deck? Head gasket thickness. Need to cc the heads too. They heads vary quite a lot in cc's so you must measure them first. Too many vairables to guess.
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#3
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440 6 pack pistons are flat with valve notches. I don't know the CC of the valve notches. Head gasket thickness will be whatever the common Fel-Pro gasket is, .040? Is it 0 deck? I don't know, I was hoping someone here would know.
I've got a '71 440 block, stock replacement 440 6 pack pistons, stock '71 forged steel crank, stock rods, and 452 heads milled just .010. The '71 440 6 pack motors had a compression ratio listed by the factory of 9.7:1 correct? If anything, the 452 heads have more CC volume than the heads used in '71. So I'm just wondering why a couple people have suggested to me that the pistons will have to be cut or my compression ratio will be too high. There's got to be someone out there that's built a 440 recently who has used the stock replacement 440 six pistons who can shed more light on this. I realize the CC of the heads is all over the map and need to be measured, just curious and looking for a ballpark until I can get my machinist to do that. |
#4
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The TWR "6-pack" pistons #2355 have a compression height of 2.061", and 7cc valve reliefs (info from TRW, not actually measured by me.)
If the block is the stock height of 10.725", the piston should be about 0.021" below the block deck. Using a 0.039" head gasket of about 9.89cc here is the compression ratio with different volume heads 80 cc head = 9.99:1 82 cc head = 9.82:1 84 cc head = 9.56:1 86 cc head = 9.49:1 88 cc head = 9.34:1 90 cc head = 9.19:1 |
#5
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Thanks so much, this helps clear up some confusion for me. It looks like this combo will be in the ballpark compression ratio-wise to run on pump gas without having to do too much.
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