![]() |
#1 |
Join Date: Jan 2008
Location: antioch
Posts: 167
|
![]()
Good day everyone.
I've been trying to figure out why the timing chain pops when rotating the motor. It's started doing this after I timed the motor. Can anyone tells me what I'm doing wrong or something that I am missing. Thank you, Shayne
__________________
1991 ZR1= Top end ported and heads Stainless headers Viper 4:10 Corsa exhaust Stainless work headers Haibeck tuned chip 2008 duramax ccsb 4x4= built Allison tranny, airdogII 165, Atp efi live stage 2 tunes, Afe ci intake, Atp egr delete, dpf delete, 5" diamond exhaust, and down pipe. 6" lift with 20x9 eagle alloy wrapped 35x12.5x20 Toyo trailgrabbler. 635hp 980tq :-D |
![]() |
![]() |
![]() |
#2 |
![]() Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
|
![]()
Most likely cam or valvetrain noise as cams rotate... tensioners might not be fully pump up .....not uncommon
__________________
LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
![]() |
![]() |
![]() |
#3 |
Join Date: Jan 2008
Location: antioch
Posts: 167
|
![]()
As I rotate the engine I can feel the chains tighten then pop. I will try to retime again maybe miss a step.
__________________
1991 ZR1= Top end ported and heads Stainless headers Viper 4:10 Corsa exhaust Stainless work headers Haibeck tuned chip 2008 duramax ccsb 4x4= built Allison tranny, airdogII 165, Atp efi live stage 2 tunes, Afe ci intake, Atp egr delete, dpf delete, 5" diamond exhaust, and down pipe. 6" lift with 20x9 eagle alloy wrapped 35x12.5x20 Toyo trailgrabbler. 635hp 980tq :-D |
![]() |
![]() |
![]() |
#4 |
![]() Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,385
|
![]()
Normal occurance after timing cams AND after removing the manual chain tensioners.
As you rotate the cams via crankshaft, there comes a point where camshafts don't have very much tension from compressed valve springs. Likewise, there are certain points in the rotation that have a significant amount of valve spring pressure working against the camshaft (and corresponding tension on the secondary timing chain). As the camshaft continues to rotate the open valve(s) pass over the lobe nose(s) and spring pressure accelerates cam rotation to that place in the rotation where there is much less spring pressure against the camshaft, and the chain slack is jerked tight. Thats the "slap" you hear. It's because the hydraulic tensioners are not pressurized from engine oil, only a bit of tensioner spring pressure. With 4 cams experiencing the same thing at different points in engine/cam rotation, there will be several chain slaps as you rotate manually. This is the same thing that you hear on startup, for that brief moment until engine oil pressure builds and the chain tensioner exerts pressure against the slack chain. It's a tad difficult to explain in words. If you recall placing the camshaft down into the journals in the head, there is that spot where it nearly lays flat, hence not much valve spring compression. As the cam rotates into that position, from high spring pressure, is when the "slap" happens.
__________________
Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. Last edited by A26B; 02-16-2024 at 02:10 PM. |
![]() |
![]() |
![]() |
#5 | |
Join Date: Jan 2008
Location: antioch
Posts: 167
|
![]() Quote:
__________________
1991 ZR1= Top end ported and heads Stainless headers Viper 4:10 Corsa exhaust Stainless work headers Haibeck tuned chip 2008 duramax ccsb 4x4= built Allison tranny, airdogII 165, Atp efi live stage 2 tunes, Afe ci intake, Atp egr delete, dpf delete, 5" diamond exhaust, and down pipe. 6" lift with 20x9 eagle alloy wrapped 35x12.5x20 Toyo trailgrabbler. 635hp 980tq :-D |
|
![]() |
![]() |
![]() |
|
|