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Old 02-03-2003, 08:07 PM
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Post Heads question

I have a set of holley systemax 2 aluminum heads for sb chevy a few questions on these heads one is the valve angle instead of being 23 degree they are 20 degree is this better or worse? 66cc combustion chambers here are the specs on them if somone knowlegable can let me know the ups and downs of these heads i would appreciate it. Also is there anything i can do to them porting wise to make them better or are they good enough

Heads (E.O. #D-115-8)
Made of lightweight 356-T6 heat-treated aluminum, these Holley heads weigh only 30 lbs. each. They're light and full of performance features:
Rectangular-shaped exhaust ports in stock O.E. locations.
Intake and exhaust valve angles changed from 23 to 20.
Combustion chamber volume: 66 cc.
Intake runner volume: 185 cc, flowing 228 SCFM @ .500" valve lift.
Exhaust runner volume: 68 cc, flowing 162 SCFM @ .500" valve lift.
Rocker arm ratio: 1.5:1
Valves: One-piece forged from 21-4N stainless steel with stellite tip and chrome-plated stem.
......Intake - 2.02" diameter
........................4.92" length
........................11/32" stem diameter
......Exhaust - 1.60" diameter
........................4.94" length
........................11/32" stem diameter
Valve Springs: Dual, with dampener
......Diameter - 1.430"
......Seat Pressure - 132 lbs.
......Open Force - 310 lbs. @ .500" lift
Valve Seat Angle:
......Top - 35
......Middle - 45
......Bottom - 60
Valve guides are made of phosphorous/bronze.
Valve Keepers: 7, steel.
Straight spark plug design.
Spark plug type: Champion C61C
........................14mm, 3/4" reach,
.........................040" gap or equivalent
Heat cross-over passage has been retained.

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Old 02-03-2003, 09:08 PM
4 Jaw Chuck's Avatar
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Use them as is and forget about it. Nothing your going to do with a hand grinder is going to fundamentally change the flow characteristics unless your some sort of psycho who likes destroying aluminum heads without a flow bench and a major team sponsor...

Forget the magazine articles and spec sheets and build it as a system, your on the right track just forget porting those beautiful works of engineering and casting technology.

Most guys here would kill for a set of heads like those never mind courting the idea of taking a grinder to them without knowing what your doing and what your trying to gain. Even a gasket match is likely unnecessary with the right gasket.

This ain't Nascar DUDE! J/K!!! :p

BTW is there such a thing as heavyweight 356-T6 aluminum? J/K!
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Old 02-03-2003, 09:20 PM
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4 Jaw has spoken!!(Crowd drops to there knees and bows).
Ok,anyhow I would clay the pistons with a differant valve angle just incase.

[ February 03, 2003: Message edited by: 78 monte ]</p>
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Old 02-03-2003, 09:50 PM
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aww hell, dig into them with some carbide bits and a power drill, theres no worse feeling then finding out the hard way that you f**ked up a set of high dollar aftermarket heads. J/K man. If you know what your doing you could pocket port them, gasket match and blend the bowls but if you dont know what your doing then leave em alone {refer to first sentence}...good luck and have fun
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Old 02-04-2003, 05:54 AM
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The heads come gasket matched, and the valve stems have been smoothed, the only thing i was thinking of doing was cleaning up the intake and exhaust ports with a little dremel sanding bit. but ill probably leave them alone.
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Old 02-04-2003, 10:03 PM
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the sanding bit will fill up with aluminum after about 5 seconds,i think to port aluminum carbide bits are the only way to fly
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Old 02-06-2003, 04:32 PM
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I don't know...filling them up with drek so they don't grind much anymore may be the best thing that could happen.
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