Need help tuning spark advance

[sturgillbd]

Log isnt that bad BLM wise. It still needs some VE tweaks. Have you verified the timing to be 0 deg with the EST connector disconnected? With the est connector reconnected and error codes cleared, verify the timing at the crank is close to what the datastream shows the PCM is commanding. Vortec heads require quite a bit more AE than TBI heads. There are several threads here on gearhead-efi on tuning for Vortec head swaps. Does it bog or pop through the intake when you stab the throttle? You may also want to try the timing tables that Fast355 has posted here on the forum. They should be a very close to what you are going to need. http://www.gearhead-efi.com/Fuel-Inj...=vortec+timing Post #6 is a start. The whole thread is about timing tables on Vortec heads.

[Jwathen23]

Yes it does bog and sometimes it will pop through the intake.. it also has no power at all at wot just before PE kicks in.. it's very flat.. and seems like it's got a miss.. I'll read through fast355 timing.. I had his timing table in until yesterday and switched to the one that a different guy gave me... fast355 timing might have been good because u haven't touched AE at all.. I have the stock timing table in now for the 98 vortec 5.7 and it's alot better then the second table I used

[Fast355]

Yes it does bog and sometimes it will pop through the intake.. it also has no power at all at wot just before PE kicks in.. it's very flat.. and seems like it's got a miss.. I'll read through fast355 timing.. I had his timing table in until yesterday and switched to the one that a different guy gave me... fast355 timing might have been good because u haven't touched AE at all.. I have the stock timing table in now for the 98 vortec 5.7 and it's alot better then the second table I used

The stock vortec table is GUTLESS in my experience.

[Jwathen23]

The stock vortec table is GUTLESS in my experience.

What's the best way for me to tweak the stock one to what my motor likes? I hate to have to just copy someone else's or stick with stock I want to learn on my own.. I'll be putting in a cam soon and I'd like to feel confident enough to spark tune it myself

[steveo]

timing can be a real bitch for a beginner, it's really by feel and curvature.

cruising range, just add timing to an area until you reach peak vacuum with a smooth feeling car and stop.

if your timing is too low in a cruise range, exhaust will smell like fuel and car will not run smoothly, and will not make good vacuum.

too much timing, vacuum levels off but engine feels 'strained', temperature goes up in combustion chamber and plugs chop sketchy, and exhaust smells like chemicals. way too much timing, vacuum drops again and you get knocks/pings.

at high vacuum (aka low map) it's safe to add quite a bit of timing, but if your engine doesn't like it, it'll protest by bucking and surging.

at heavy throttle, most people just advance it until you find knock and back it off a couple degrees.. a dyno is ideal, though, since sometimes peak power is WAY before the point of knock, and less timing is way safer than more timing.