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Old 05-12-2007, 05:57 PM
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Milling Heads for more compression

383 SBC w/Dart iron Eagle heads 200/64cc. Replacing cam with a Herbert solid roller and since heads are coming off for new springs I thought I need to increase compression as well. Presently 9.67:1 Speed Pro dished. Want to mill heads to achieve around 10.3. and smaller chambers will result as well 59cc - 61cc ??? Would appreciate hearing from those that have gone this route to achieve slight compression increases. Cam is .608 lift with 1.6 rockers 244 duration. I know I need more compression with this cam but dont want to mill over .030. Thoughts appreciated.

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Old 05-12-2007, 08:37 PM
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Depending on valve size, you may end up milliing into the intake valve seat, necessitating sinking the valve, which would kinda make the chamber bigger, necesstating milling the heads more, in which you may end up milliing into the intake valve seat............


tom
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Old 05-13-2007, 08:01 AM
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Milling Heads - Compression ratio formula

DART sez heads can be milled .060" and that .0065" = 1cc.
I am trying to calculate what the compression ratio would be milling at .030"
I know there is a guide to milling that states chamber size and computes compression. Anybody aware of this???????
THNAKS!!!
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Old 05-13-2007, 10:23 AM
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Milling Heads - Compression ratio formula

Good advice F-BIRD, I thought about just changing gaskets but didn't know if I would achieve exact effects of milling. Seems that .023"milling would put me around 10.3. (if all numbers are close as you stated) I normally run a blend of 97 + 104 octane, no pinging @35total timing, however did ping @37.
Motor loves the higher octane now, so I don't have a problem running the pricey stuff, car doesn't see many miles. My thoughts : increased bottom end torque with smaller chambers (around 59s) part of what got me headed in the milling direction plus need for higher compression with this duration cam. Now I might consider just cleaning them up .010 and installing the new springs. Thanks for the input, very helpful.
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Old 05-13-2007, 12:06 PM
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Milling Heads - Compression ratio formula

Looks like your advice may be the way to proceed. Cam is a 110 LSA and states best to install @ 106 my application. Guess I'm wrong about plugs, I thought colder would ping more. Jetting needs to go up 1 or 2 sizes I think (new carb with base Holley 750 jetting). With large tube headers and now the bigger carb I can use more bottom. Thanks again!
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Old 10-12-2007, 07:11 PM
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"1cc per .00065" " seems like an extra zero?

I shaved my heads .030" & I don't think my combustion chambers decreased by 46cc , It looks like about 3.2cc to me.

BBP

Last edited by BUFFALOBILLPATRICK; 10-12-2007 at 08:31 PM.
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Old 10-12-2007, 07:50 PM
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With a .600 lift cam milling your heads will probably nessesate fly cutting the pistons which for compressions sake will be be defeating the purpose.
I'd mock it up and clay your pistons first befor you go milling anything.
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