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port and polish

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Old December 6th, 2009, 09:23 AM
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port and polish

i have 72 350 7a heads that i did a port and polish on. ive been told its best not to polish the intake ports. should i just go over them with a heavier grit sandpaper and do i do the entire port or just the side walls?
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Old December 6th, 2009, 10:49 AM
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Inside where it is rough is where the air and fuel mix. If you smooth it out you will ruin the heads. You can make the opening bigger use the intake gasket as a template.
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Old December 6th, 2009, 11:09 AM
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Just go over them with a coarse sandpaper roll in a drill or die grinder.
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Old December 6th, 2009, 11:57 AM
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do i do the entire intake port this way? I thought the air and fuel mixed inside of the intake manifold?
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Old December 6th, 2009, 03:45 PM
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not the valve seats of course. Sure air and fuel mix at the carb, but you don't want to encourage fuel to drop out of suspension along the way. Years ago, Mopar max wedge racers found that the rougher castings actually helped power.
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Old December 6th, 2009, 05:22 PM
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ok thanks and do you think my valve springs are ok.

Dual Valve Springs I.D. of Outer Dia.: 1.073"
I.D. of Inner Dia.: .697"
Seat load: 121lbs @1.700''
Open load: 337lbs @1.150''
Coil bind: 1.020''
Rate: 392lbs/in
my cam is a hydraulic roller int528 exh 547 duration is int248 exh254. lsa 110. im going to have it ground down a little more though so my duration will be in the 230's
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Old December 6th, 2009, 07:39 PM
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You might want to have it ground for more lift as well. If you have good flowing heads lift is horsepower without losing much driveability if any. I have a brand new Erson Hyd Roller for sale if you're interested, 226/234 @ .050, on a 112, .584 lift with 1.6 rockers.

Last edited by cutlassefi; December 6th, 2009 at 07:42 PM.
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Old December 6th, 2009, 08:48 PM
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Can my cam be ground for more lift? I know i can reduce the duration.
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Old December 6th, 2009, 08:58 PM
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Technically yes but it will reduce the base circle.
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Old December 6th, 2009, 09:02 PM
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what is the base circle? should i have it ground down. its a custom ground cam so i cant return it
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