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Old 04-20-2009, 10:05 PM
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Open chamber heads with closed chamber pistons

I have a set of Speed Pro L2349F pistons. Can I use a open chamber head like #781's with these pistons?

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Old 04-20-2009, 10:12 PM
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Yes, you can do this. The opposite(closed heads, open pistons) is where you have interference problems between the dome and the chamber.
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Old 04-21-2009, 01:12 AM
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I agree, no worries. But check your compression math. You might end up with 7:1
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Old 04-21-2009, 04:57 PM
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Hold on guys!. In some instances the 427 dome will hit the chamber at the very outside edge, exhaust side, just above the flat part of the piston. Just take a cutter and trim the piston in this area, back about 1/8".

I have seen many of these since the early seventies when the OC heads became available.
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Old 04-28-2009, 09:32 AM
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So which head is better for my application (drag racing)? Currently my combo is a 454 +.030 (4.285 bore), stock stroke (4.00"), stock deck height and L2349F Speed Pro pistons. My current heads are 215 casting 101cc closed chamber, stock valves. I have a chance to buy a pair of 781's 118cc open chambers with 2.25 intakes and 1.88 exhausts. I know the motor ran well with the 215's even though the guides are worn out and it had a flat cam lobe and about 6 inner valve springs broke. I'm debating on whether to sink money in the 215's or go ahead and buy the 781's. I know the 781's will lower my compression but is this a bad thing for a race engine? Will lowering the CR also lower my HP and torque? Need help deciding on which way to go. Changing the pistons is not an option at this time due to $$.
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Old 04-28-2009, 01:04 PM
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Stick with what you got.
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Old 04-28-2009, 01:06 PM
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Do you know what the compression ratio is now? You are going to lose a good amount if you change heads because of the 17cc difference. Lowering compression will lower the torque and hp but it is possible for better airflow to make up for some or all of the loss. Need more info.
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