LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Timing question

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Old Jan 22, 2010 | 06:41 PM
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396 with a LE 236/242 612/612 111lsa what should my timing tables look like?
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Old Jan 22, 2010 | 06:48 PM
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What heads? what CR? installed ICL? what quench clearance? what fuel? what tstat? what coolant?
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Old Jan 22, 2010 | 06:54 PM
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le2 heads 12.1 to1 cr. 36lbs injectors 160 stat coolants green. i dont know the quench clearance and i dunno what the ICL stands for.?
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Old Jan 22, 2010 | 07:27 PM
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quench = compressed head gasket thickness + deck clearance (how far the piston is in the hole at TDC)
ICL = installed centerline of the intake lobe (degrees after TDC)
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Old Jan 22, 2010 | 07:47 PM
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.052 quench
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Old Jan 22, 2010 | 07:50 PM
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i dont know on icl i didnt degree the cam in
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Old Jan 22, 2010 | 09:28 PM
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I'm going to assume 93 octane fuel and ICL of 105-106 deg.
I've attached a file of the timing table I'm running based on the dyno tune. I have 12.0 CR, .037 quench. 228 dur cam, 105 ICL, 350 ci. Dyno tuned with race gas, but from the modest timing needed for best power, I'm running 93 in it.
With your less optimal quench, you may want to pull 2 degrees out everywhere between 30 and 85 kpa and between 1400 and 7000 rpm, and then smooth the cells with adjacent ones. Adjust further as necessary if you think the ICL may be smaller (earlier) and/or if running less than 93 octane.
Attached Files
File Type: doc
GishTiming.doc (56.5 KB, 169 views)
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Old Jan 22, 2010 | 09:47 PM
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thank you very much sorry i dont know the exact numbers im a newbie kinda
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Old Jan 22, 2010 | 09:50 PM
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exactly what i expected my tuner is way low on the timing. i told him i thought it need more initial timing. we were off by like 7 degrees. when the car hits closed loop it runs horrible. i think its at 21 degrees at 1000rpm
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Old Jan 22, 2010 | 09:52 PM
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Originally Posted by draggin97s10
exactly what i expected my tuner is way low on the timing. i told him i thought it need more initial timing. we were off by like 7 degrees. when the car hits closed loop it runs horrible. i think its at 21 degrees at 1000rpm
In what map and rpm ranges are you saying he is low?
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Old Jan 22, 2010 | 09:57 PM
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1000 rpm at 25kpa
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Old Jan 22, 2010 | 10:01 PM
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Originally Posted by draggin97s10
1000 rpm at 25kpa
I doubt it matters in that corner of the table. Your engine surely idles over 50 kpa with that cam.
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Old Jan 22, 2010 | 10:09 PM
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ok take into mind i know hardly anything about FI tuning. i got a matco scan tool that shows live readings at idle and its at 21 to 23 i cant remeber kpa. doesnt that seem low to you?
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Old Jan 22, 2010 | 10:14 PM
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not extremely low, that's about 5 deg lower than mine at idle (1000 rpm, 60 kpa)
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Old Jan 22, 2010 | 10:19 PM
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ok well in open loop the thing runs stupid fast hits closed and runs like a festiva. all new hardware. no leaks vacume /exhaust. the intake has tons of raw fuel in it and hes leaned the fuel tables way out im going crazy. i know its a shot in the dark without you being able to look at the car in person but any ideas
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Old Jan 22, 2010 | 11:25 PM
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Originally Posted by draggin97s10
ok well in open loop the thing runs stupid fast hits closed and runs like a festiva. all new hardware. no leaks vacume /exhaust. the intake has tons of raw fuel in it and hes leaned the fuel tables way out im going crazy. i know its a shot in the dark without you being able to look at the car in person but any ideas
I'm no experienced tuner, but I know cams with a lot of overlap (yours and mine) will always play havoc with the O2 sensors and PCM at idle speeds with all the unburnt fuel and air going out the exhaust.
Since my MAF tables are scaled from the dyno tune, I'm running mine open loop just to avoid the rich issues you mention. When we first fired up the engine with the rough program before the dyno tune, it went into the same fits you describe as soon as it hit closed loop. I put so few road miles on the car, that I may not even mess with getting it to behave in closed loop. It seems to run so good at all speeds and loads right now, I doubt there's even much mpg to be gained with closed loop.
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Old Jan 22, 2010 | 11:29 PM
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this is what i tryed to talk to him about an OL tune. and he says well it should run in CL but i figure an OL tune would be much much better for what im using the car for and even when i drive it on the street i dont car about mpg. that 3 letter abreveation makes me laugh so should i just through an OL tune on it to solve these fits
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Old Jan 23, 2010 | 07:28 PM
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need info on open loop tune...
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