ignition timing advance for the LT1
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ignition timing advance for the LT1
This winter I rebuilt my 93 LT1; hot cam, 1.6rr's, TF 185 heads, Impala head gasket, 355, LT headers. I am having trouble with cam surge. From idle to 2000rpm the car bucks terrible, especially in 1st thru 4th (6 spd). I have looked at my timing from the tuner and see 50 degrees of advance sometimes at cruise, seems like way too much to me? What are you guys running with the hot cam for spark advance?
http://s1113.photobucket.com/albums/...t=IMG_4513.jpg
http://s1113.photobucket.com/albums/...k520%2Fphotoba
http://s1113.photobucket.com/albums/...k520%2Fphotoba
http://s1113.photobucket.com/albums/...t=IMG_4513.jpg
http://s1113.photobucket.com/albums/...k520%2Fphotoba
http://s1113.photobucket.com/albums/...k520%2Fphotoba
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My last data log shows a knock count over 8000 isn't that high?
http://s1113.photobucket.com/albums/...atalogAug4.jpg
http://s1113.photobucket.com/albums/...atalogAug4.jpg
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Joined: Aug 2009
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From: Plano, TX
The stock 93 corvette timing tables work pretty well. I had to pull a little timing because I'm at 11.0 CR. 50 is definitely on the high side. The highest I ever use is 42 and that is in the cells where the engine has high vacuum ie coast down 0 throttle.
Your knock counts are not normal.
I've not had much luck using timing to get rid of cam surge. The VE tables are more effective at reducing cam surge for my car. You won't ever completely be rid of the cam surge but it can be tamed quite a bit.
Your knock counts are not normal.
I've not had much luck using timing to get rid of cam surge. The VE tables are more effective at reducing cam surge for my car. You won't ever completely be rid of the cam surge but it can be tamed quite a bit.
Last edited by 93VettePilot; Aug 4, 2012 at 06:19 PM.
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93VP, thanks for the reply. I think I will go back to the stock timing and just try it and see if it helps. I have no idea how to try and change the VE tables. I am installing a Lambda gauge to read my fuel, maybe I can get some idea where I am with A/F.
Le Mans Master
Joined: Feb 2005
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From: Clearwater Florida
........... As I understand it ... roller rockers can induce a knock noise to the sensor ... It seems to me , if memory serves me well , that LT4's got a different knock sensor for this very reason ..........
