Tune/incorrectly used cam cause valve train knocking?
08-03-2023 | 11:17 PM
#1
Thread Starter
Launching!
Joined: Jan 2023
Posts: 235
Likes: 34
From: Corpus Christi, TX
Tune/incorrectly used cam cause valve train knocking? Hello kinda new here especially in this section. I will try to keep my questions to a minimum and read as much as possible before you hear me again.
2008 Silvy 6.0 with an LS7 cam yes Light me on fire, Tuned in West TX didnt have issues but the idle was really rough and was overheating after warming up in town at stop lights. Planned to let him retune it but he left town for awhile and I moved south. I had a cam failure a month or so after the tune. I replaced with what appeared to be a better condition ls cam. Just like the last failure after driving the truck for another 2 months it started to make identical noise of the failure when it would lope at idle goes away when driving full speed but it definitely sounds off. I decided to take it apart unlike driving on the last one for a week or 2. This cam doesnt show any sines of failure though i drove the other one for quite some time before i exposed 3 lifters belled retrieved from inside. Both cams seemed to run identically. Other than a rough idle, when accelerating 1200-1800 any gear and not flooring it would hesitate and the entire truck would "jerk".
Long Question Short can a bad tune cause knocking at low rpm/cam failure? I wish I had some data but I tore the truck apart before my HPTuners arrived trying to diagnose what to order. Can always reassemble and try to replicate the situation and I am weighing this option to confirm there are no issues with my lower end.
The initial cam was used with me being inexperienced and him the guy saying run it with 100 grand worth of decent chevys and a garage where he said he built motors his whole life. This man also told me the hood static cable was to stop the hood from flying up I should have taken that as a red flag to get another mechanic involved.
If you care to overlook
6.0 with LS7 cam 210°/230° 120 LSA advance -3°
Stock intake honeycomb removed from mafStock 823 heads BTR platinum SP015-16 springsStock headers to cat removed free flow after YEverything else is stock
2008 Silvy 6.0 with an LS7 cam yes Light me on fire, Tuned in West TX didnt have issues but the idle was really rough and was overheating after warming up in town at stop lights. Planned to let him retune it but he left town for awhile and I moved south. I had a cam failure a month or so after the tune. I replaced with what appeared to be a better condition ls cam. Just like the last failure after driving the truck for another 2 months it started to make identical noise of the failure when it would lope at idle goes away when driving full speed but it definitely sounds off. I decided to take it apart unlike driving on the last one for a week or 2. This cam doesnt show any sines of failure though i drove the other one for quite some time before i exposed 3 lifters belled retrieved from inside. Both cams seemed to run identically. Other than a rough idle, when accelerating 1200-1800 any gear and not flooring it would hesitate and the entire truck would "jerk".
Long Question Short can a bad tune cause knocking at low rpm/cam failure? I wish I had some data but I tore the truck apart before my HPTuners arrived trying to diagnose what to order. Can always reassemble and try to replicate the situation and I am weighing this option to confirm there are no issues with my lower end.
The initial cam was used with me being inexperienced and him the guy saying run it with 100 grand worth of decent chevys and a garage where he said he built motors his whole life. This man also told me the hood static cable was to stop the hood from flying up I should have taken that as a red flag to get another mechanic involved.
If you care to overlook
6.0 with LS7 cam 210°/230° 120 LSA advance -3°
Stock intake honeycomb removed from mafStock 823 heads BTR platinum SP015-16 springsStock headers to cat removed free flow after YEverything else is stock
Last edited by Guy with a Chevy; 08-03-2023 at 11:44 PM.
08-04-2023 | 08:00 AM
#2
Hello kinda new here especially in this section. I will try to keep my questions to a minimum and read as much as possible before you hear me again.
2008 Silvy 6.0 with an LS7 cam yes Light me on fire, Tuned in West TX didnt have issues but the idle was really rough and was overheating after warming up in town at stop lights. Planned to let him retune it but he left town for awhile and I moved south. I had a cam failure a month or so after the tune. I replaced with what appeared to be a better condition ls cam. Just like the last failure after driving the truck for another 2 months it started to make identical noise of the failure when it would lope at idle goes away when driving full speed but it definitely sounds off. I decided to take it apart unlike driving on the last one for a week or 2. This cam doesnt show any sines of failure though i drove the other one for quite some time before i exposed 3 lifters belled retrieved from inside. Both cams seemed to run identically. Other than a rough idle, when accelerating 1200-1800 any gear and not flooring it would hesitate and the entire truck would "jerk".
Long Question Short can a bad tune cause knocking at low rpm/cam failure? I wish I had some data but I tore the truck apart before my HPTuners arrived trying to diagnose what to order. Can always reassemble and try to replicate the situation and I am weighing this option to confirm there are no issues with my lower end.
The initial cam was used with me being inexperienced and him the guy saying run it with 100 grand worth of decent chevys and a garage where he said he built motors his whole life. This man also told me the hood static cable was to stop the hood from flying up I should have taken that as a red flag to get another mechanic involved.
If you care to overlook
6.0 with LS7 cam 210°/230° 120 LSA advance -3°
Stock intake honeycomb removed from mafStock 823 heads BTR platinum SP015-16 springsStock headers to cat removed free flow after YEverything else is stock
2008 Silvy 6.0 with an LS7 cam yes Light me on fire, Tuned in West TX didnt have issues but the idle was really rough and was overheating after warming up in town at stop lights. Planned to let him retune it but he left town for awhile and I moved south. I had a cam failure a month or so after the tune. I replaced with what appeared to be a better condition ls cam. Just like the last failure after driving the truck for another 2 months it started to make identical noise of the failure when it would lope at idle goes away when driving full speed but it definitely sounds off. I decided to take it apart unlike driving on the last one for a week or 2. This cam doesnt show any sines of failure though i drove the other one for quite some time before i exposed 3 lifters belled retrieved from inside. Both cams seemed to run identically. Other than a rough idle, when accelerating 1200-1800 any gear and not flooring it would hesitate and the entire truck would "jerk".
Long Question Short can a bad tune cause knocking at low rpm/cam failure? I wish I had some data but I tore the truck apart before my HPTuners arrived trying to diagnose what to order. Can always reassemble and try to replicate the situation and I am weighing this option to confirm there are no issues with my lower end.
The initial cam was used with me being inexperienced and him the guy saying run it with 100 grand worth of decent chevys and a garage where he said he built motors his whole life. This man also told me the hood static cable was to stop the hood from flying up I should have taken that as a red flag to get another mechanic involved.
If you care to overlook
6.0 with LS7 cam 210°/230° 120 LSA advance -3°
Stock intake honeycomb removed from mafStock 823 heads BTR platinum SP015-16 springsStock headers to cat removed free flow after YEverything else is stock
08-04-2023 | 09:00 AM
#3
There is not alot changed in the tune, a lot of VVE changes and added some timing. Just quickly looking through the tune didnt see anything jumping out thats in left field. If I get some time I'll look through it some more. Without a lot wont know what the truck was doing though.
08-04-2023 | 05:07 PM
#4
They advertise that cam with .558 lift on a 1.7 ratio rocker.
The BTR Springs are only rated to .560 lift... I don't know for sure if the go into Coil bind at .560 but if they do, your talking .002 clearance. An average human hair is like .004 thick. That's not enough head room to control the valves under high RPM That's likely why your eating lifters and ruining cam shafts.
Despite the advertised spec's, I can guaranty you a cam is never perfectly ground to the exact spec. That being said, the only way to know, would be to have it measured for true accuracy.
Same with coiled valve springs, They have a range they have to be within. I believe its within 5% of the target range. They select a specific wire and twist them to a specified coil length. Then they are finished ground to size to give them a flattish mounting base.
The BTR Springs are only rated to .560 lift... I don't know for sure if the go into Coil bind at .560 but if they do, your talking .002 clearance. An average human hair is like .004 thick. That's not enough head room to control the valves under high RPM That's likely why your eating lifters and ruining cam shafts.
Despite the advertised spec's, I can guaranty you a cam is never perfectly ground to the exact spec. That being said, the only way to know, would be to have it measured for true accuracy.
Same with coiled valve springs, They have a range they have to be within. I believe its within 5% of the target range. They select a specific wire and twist them to a specified coil length. Then they are finished ground to size to give them a flattish mounting base.