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

knock issue...

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Old Jul 16, 2009 | 05:19 PM
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Default knock issue...

hey guys, need a hand.
i recently upgraded my valvetrain from roller tip 1.6s, hotcam springs, stock lifters, and stock pushrods. i swapped in 1.65 full rollers(sa), crane 10308-1 springs/retainers, stock replacement lifters, and trickflow pushrods(7.100 as measured) also have the lt4 km...
before the swap i wasnt getting knock counts, and right after the swap i was getting very sporadic counts. at first i thought i just needed to pull a bit of timing, but after doing so, and even going back to the trifecta tune with only 20* at idle, im still getting knock... and my trims are 127-129.
im currently at 1/2 past lash, and will try adding another 1/4 turn, but aside from that, im really at a loss here. the valvetrain really doesnt sound a whole lot louder than it did before, and i cant hear any other knock in the engine.
im gonna change the oil and cut the filter this weekend to see if theres anything up with the bearings.
idk guys, any input would be much appreciated.
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Old Jul 16, 2009 | 05:47 PM
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Originally Posted by laux06
hey guys, need a hand.
i recently upgraded my valvetrain from roller tip 1.6s, hotcam springs, stock lifters, and stock pushrods. i swapped in 1.65 full rollers(sa), crane 10308-1 springs/retainers, stock replacement lifters, and trickflow pushrods(7.100 as measured) also have the lt4 km...
before the swap i wasnt getting knock counts, and right after the swap i was getting very sporadic counts. at first i thought i just needed to pull a bit of timing, but after doing so, and even going back to the trifecta tune with only 20* at idle, im still getting knock... and my trims are 127-129.
im currently at 1/2 past lash, and will try adding another 1/4 turn, but aside from that, im really at a loss here. the valvetrain really doesnt sound a whole lot louder than it did before, and i cant hear any other knock in the engine.
im gonna change the oil and cut the filter this weekend to see if theres anything up with the bearings.
idk guys, any input would be much appreciated.
Did you adjust the valves with the engine running?
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Old Jul 16, 2009 | 05:52 PM
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no, with the engine off. its how ive done it in the past without issue. i will definitely give it a try this weekend though. do you think slightly misadjusted rockers would cause this much knock? i can email a log if you want to see exactly when/where its happening. thanks!
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Old Jul 16, 2009 | 06:17 PM
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after scouring this site, seems most folks are editing their burst knock tables... does this sound like it might be my problem? ive been pulling LOTS of timing, like 6* across the board and still getting knock, would this point to false knock? i found a thread that a guy used to "desensitize" the burst knock tables, im gonna give that a shot tonite and see what happens. any other input would be greatly appreciated
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Old Jul 16, 2009 | 06:25 PM
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Originally Posted by laux06
after scouring this site, seems most folks are editing their burst knock tables... does this sound like it might be my problem? ive been pulling LOTS of timing, like 6* across the board and still getting knock, would this point to false knock? i found a thread that a guy used to "desensitize" the burst knock tables, im gonna give that a shot tonite and see what happens. any other input would be greatly appreciated
Usually with a performance tune the knock sensor is desensitized, but I'm not a tuner so I can't tell you exactly how.
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Old Jul 17, 2009 | 12:44 AM
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ok cool man, well im gonna give this a shot(last post at the bottom) tmw and cross my fingers. its almost gotta be false knock if it JUST started happening after installing full rollers, so hopefully this does the trick. ill keep ya posted, thanks
https://ls1tech.com/forums/lt1-lt4-m...ck-sensor.html
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Old Jul 26, 2009 | 07:11 PM
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alright, finally got a chance to work on the car today. i went back and readjusted all the rockers with the engine running this time. backed off till they clacked, tightened till no noise, then a quick half turn, and it stumbled then corrected itself. every rocker reacted just as it should have. now the engine sounds great, and the first time i took it around the block, no knock. then i left it in the driveway running, and got 2 knocks in 5 minutes. its a marked improvement, but its still there. also, i listened to each rocker with a screwdriver w/the covers off, and they all sound the same. then i listened to oil pan and timing cover, no noise out of the normal there either. finally i tapped the block with a prybar and the knock count went up by like 20 counts, and it did almost die. my neighbor has suggested first backing the knock sensor out a hair to see if that helps, then try wrapping it with teflon. so that will be my next plan of action, any other ideas or suggestions would be greatly appreciated. thanks
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