Vortec head rebuild

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PlayingWithTBI

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Be nice to see numbers @ .550 and @.525 to see where it begins to fall off.
Yeah, these charts show that the Vortec, 882, and GMPP "Fast Burn" all start to drop off over .500" where the TBI Summit Racing aluminum heads (170cc runner, 62cc chamber, 2.02/1.60" fast burn design with slant plugs (made by Trick Flow) continue to flow up to .600" :33:
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Maybe, if you can afford it, spend a couple bucks more for aluminum heads that'll work with Vortec design?:waytogo:
 
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98 Nitro

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Flow numbers for new vortec heads sold by Pace. The stock Vortec 305 heads flow at least as good. If your stock 99 ones check out good use them, otherwise go aftermarket Vortec.
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L31MaxExpress

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Flow numbers for new vortec heads sold by Pace. The stock Vortec 305 heads flow at least as good. If your stock 99 ones check out good use them, otherwise go aftermarket Vortec.
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This is what my out of the box Assault castings with zero work and untouched seats and aftermarket valves not yet even cut. A little bowl work and decent valve job gets these up around 265 cfm @ 0.600.

LIFT------INTAKE-----EXHAUST
.200----------135-------103
.300----------183-------131
.400----------225-------150
.500----------244-------164
.600----------241-------175
.700----------241-------177

After Lloyd Elliot did some work to them.
LIFT------INTAKE-----EXHAUST
.200----------138-------107
.300----------192-------138
.400----------241-------164
.500----------274-------183
.600----------295-------193
.700----------299-------199
 

Erik the Awful

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If your cam is .525" lift with 1.5 rockers and you're putting 1.6 rockers on those heads, you'll need to cut down the valve guides. Quick math says you'll be running .560" lift. The stock Vortec heads usually fit up to .530" lift with 1.5 rockers and beehives. Be sure and measure your valve seal clearance!
 
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