CAMARO6 - View Single Post - Destroyed Cam Motion Cam and Johnson Lifters

cmitchell17 · 03-30-2024, 07:26 PM

I replaced all the exhaust flange and manifold gaskets, and while I was at it I figured I would try putting in the 7.925 pushrods I ordered. Then I noticed the LS7 lifters had become solid then I noticed the 7.925s was holding the valves open. So I put the 7.900 I had been running back on and then the valve was still being held open. So couldn't figure out what was going on, especially with the very unpredictable way these lifters will pump up all the way solid even with a cold engine that hasn't been ran in 24 hours, and then no matter how long you wait they never bleed down, even 3 years because I had my original non-AFM lifter still pumped all fully all the way after 3 years of sitting there.

So I know for sure when I put in the 7.900s in a few weeks ago I had around 0.085 preload, so I figured even though I could clearly see the valve open, I would try the 7.925's anyway. So I did and I couldn't start it at all, you could hear the starter just spin with no load and it fire off a little but nothing, it wouldn't build any compression.

So tore it back apart again, and decided to go the opposite direction and put in some older 7.800 pushrods I had from my original cam install even though I was only getting about 0.040 of preload with them, they would allow the valves to close. The lifters also still felt fully pumped up and solid since you couldn't press them down no matter how hard you pushed on the top of the pushrod.

So it seems like the noise is the same. It may be HPFP related just because it gets really bad at around 1800-2000 rpms, then once you get past about 2200 rpms it almost disappears. It's real "clickity" sounding. These springs are supposed to be .710 max lift but I am wondering if they are binding somehow. I want to try the conicals but I just can't find any retainers since I can't find my original retainers and I think they got thrown away when my heads got CNC'ed.

03-30-2024, 07:26 PM	#60
cmitchell17 Drives: 17 2SS, 8L90, Cam, Heads, E85 Join Date: Dec 2016 Location: US Posts: 1,213	I replaced all the exhaust flange and manifold gaskets, and while I was at it I figured I would try putting in the 7.925 pushrods I ordered. Then I noticed the LS7 lifters had become solid then I noticed the 7.925s was holding the valves open. So I put the 7.900 I had been running back on and then the valve was still being held open. So couldn't figure out what was going on, especially with the very unpredictable way these lifters will pump up all the way solid even with a cold engine that hasn't been ran in 24 hours, and then no matter how long you wait they never bleed down, even 3 years because I had my original non-AFM lifter still pumped all fully all the way after 3 years of sitting there. So I know for sure when I put in the 7.900s in a few weeks ago I had around 0.085 preload, so I figured even though I could clearly see the valve open, I would try the 7.925's anyway. So I did and I couldn't start it at all, you could hear the starter just spin with no load and it fire off a little but nothing, it wouldn't build any compression. So tore it back apart again, and decided to go the opposite direction and put in some older 7.800 pushrods I had from my original cam install even though I was only getting about 0.040 of preload with them, they would allow the valves to close. The lifters also still felt fully pumped up and solid since you couldn't press them down no matter how hard you pushed on the top of the pushrod. So it seems like the noise is the same. It may be HPFP related just because it gets really bad at around 1800-2000 rpms, then once you get past about 2200 rpms it almost disappears. It's real "clickity" sounding. These springs are supposed to be .710 max lift but I am wondering if they are binding somehow. I want to try the conicals but I just can't find any retainers since I can't find my original retainers and I think they got thrown away when my heads got CNC'ed.