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rustyzipper
Joined: 08 Oct 2009 Posts: 67
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Posted: Tue Jul 24, 2012 4:31 pm Post subject: KEM SBC 350 TBI timing question |
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installed new short block and re-assembled rest of engine. timed dizzy, boat runs ok and shows 8* advanced on timing gun at idle how do i set final timing? and to what? ALDL connector has a cap with a BLK wire that comes out of it and loops back into another wire on the same ALDL port( all appears factory or OEM). Someone told me to jump A & B to set base timing, when I did that the engine fires up then shuts right off and wont run at all, I disconnected my A&B jumper wire and boat still wouldnt run until i gave it throttle. any help please. boat is a 1995 jetcraft with a 1985-1995 SBC 350 with TBI. |
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ALEX
Joined: 02 Aug 2005 Posts: 176 Location: red deer
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Posted: Wed Jul 25, 2012 9:19 am Post subject: |
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I am not sure which engine/distributor you have by your description but most marine engines should be set for total timing at 3000rpm.
If yours is pre vortec 32 deg total.Vortecs should be no more than 28deg total.
To set total timing you need an adjustable timing lite;set the readout at the required timing;run the engine to 2500-3000 and line the timing marks up at zero. |
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rustyzipper
Joined: 08 Oct 2009 Posts: 67
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Posted: Thu Jul 26, 2012 12:03 pm Post subject: |
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ok ..heres what I did. I started engine without jumper wire installed on A&B terminal on ALDL. while engine running I then installed jumper wire to A&B, engine then ran at about 400 rpm and took computer controlled ignition off line, I then set base timing to 10* BTDC(just at 400 rpm idle giving no throttle) Whille engine still idling I disconnected A&B jumper wire and computer took over and gave me about 1100 rpm while cold start and 850 RPM idle when warmed up. I still cant read final ignition timing cause computer takes over and is constantly adding or subtracting advance when computer(ecm) connected, timing light readings are all over the place. I've been told ecm adds anywhere from 20*-30* advance depending on input sensor readings from other areas such as water temp, air speed, air density, oil pressure and throttle position sensors. |
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