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Old 11-15-2007, 03:01 AM
66KGold 66KGold is offline
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Default Max Lift for TRW Pistons W/ Valve Reliefs

Hi guys, I was just wondering if anyone knows how much lift you can run with TRW forged 440 pistons with the 4 valve reliefs. I got my hands on a Mopar Performance 557" lift cam and I was wondering if I could use it with my motor, I have 1.6 rockers and edelbrock heads. Also the block has not been decked or anything so it's still stock height. Thank you very much for any help.

Justin
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Old 11-15-2007, 03:56 AM
DartGT66 DartGT66 is offline
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The lift is only one factor. The valves are closest to the pistons at between 10 degrees before top dead center, and 10 degrees after top dead center. At that point the valves are not open much of their total lift. So, other factors are cam degrees, and even cam timing. I think no one can answer your question unless he has had the same exact combo with the same deck heights etc. I would say that you are so close, that you must verify the clearance and possibly make a little more room. I have had a pretty similar combo, 2.14/1.81 valves, zero deck flat top pistons and the 296/.557 cam in a 440. In my case, I had to make small valve reliefs (didn't have any, used 2266 TRW's and .090" milled block) . I would say they were about the same size as the valve reliefs in the six pack pistons, but it's better to check than to be sorry.
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Old 11-15-2007, 09:51 AM
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JVMopar JVMopar is offline
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I agree use the old head gasket and some modeling clay and check the piston to valve clearence. Should be 0.100" or so I've read. Some sources say less but better to be safe than have to buy pistons, heads, bore and hone, etc, etc, etc.
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Old 11-15-2007, 10:20 AM
DartGT66 DartGT66 is offline
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Exhaust is more critical, you want at least 0.1" clearance there, and you donät have to watch your rpm and valvesprings so frequently
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Old 11-18-2007, 03:09 PM
66KGold 66KGold is offline
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Thank you for the help, I did the clay test and there was plenty of clearence.
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