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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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ignition timing on an '81 928 US-spec
Does anyone know what the ignition timing (loosen the 13mm bolt on the distributor & twist the distributor) value should be on an '81 Us-spec L-jet engine?
I can't seem to find my volume that covers this model. Thanks!
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-11-2007, 10:58 AM
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Join Date: Aug 2006
Location: Cincinnati, Ohio
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30 BTDC at 3000 RPM...remove the vacuum advance line. If you're turbocharging it you MUST take out some ignition...those old distributors work great with just minor mods. 8 to 10 degrees on about 10 psi seems to work pretty well.
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Kuhn Performance Technologies, LLC Big Gun: 1988 928S4 Twin Turbo, 5-SPD/LSD 572 RWHP, 579 RW ft-lbs, 12 psig manifold pressure. Stock Internals, 93 octane. Little Gun: 1981 928 Competition Package Twin Turbo, 375 RWHP, 415 RW ft-lbs, 10psig manifold pressure. Nikasil Block, JE2618 Pistons, 93 octane. |
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05-11-2007, 01:27 PM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
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this one is NA for now, but I dont see any ticks for 30d BTDC on my blue harmonic damper: Did I miss something? I've never had an L-Jet 928 before.
Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-11-2007, 01:35 PM
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Mark,
I told you wrong...it is 23 btdc at 3000. 30 is the max advance on that system. Disconnect the vacuum advance and run the car to 3K with the light attached. If you boost it, you must take about 7-10 degrees out for about 10 psig. 16V ring lands are very weak. JK
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Kuhn Performance Technologies, LLC Big Gun: 1988 928S4 Twin Turbo, 5-SPD/LSD 572 RWHP, 579 RW ft-lbs, 12 psig manifold pressure. Stock Internals, 93 octane. Little Gun: 1981 928 Competition Package Twin Turbo, 375 RWHP, 415 RW ft-lbs, 10psig manifold pressure. Nikasil Block, JE2618 Pistons, 93 octane. |
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05-23-2007, 04:08 AM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
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That's where I had set it: thanks!
Mark.
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-23-2007, 05:25 AM
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Join Date: Sep 2004
Location: Saxton, Pa
Posts: 27
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Mark;
I've had better performance at 27-28 deg. on L-jet cars. Make sure your vacuum system is tight, no leaks. |
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05-23-2007, 12:57 PM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
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Ok, will try that too. thanks Scott, Mark.
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-24-2007, 05:46 AM
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Location: Cincinnati, Ohio
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Set it to 23 max advance and add 10 psi to the manifold
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Kuhn Performance Technologies, LLC Big Gun: 1988 928S4 Twin Turbo, 5-SPD/LSD 572 RWHP, 579 RW ft-lbs, 12 psig manifold pressure. Stock Internals, 93 octane. Little Gun: 1981 928 Competition Package Twin Turbo, 375 RWHP, 415 RW ft-lbs, 10psig manifold pressure. Nikasil Block, JE2618 Pistons, 93 octane. |
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05-24-2007, 07:54 AM
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