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i have a 571 571 lift 276/282 duration 224/228 @50 cam, stock lq4 lifters, trunion kit , and pac 1218 springs.. valves very noisy and I know the cam was reground from a damaged large cam so I checked pushrod as some described on internet with 0 lash then rotation and was bit short so I got 7.450 pushrods and helped some.. buts its still very annoying... is this common? .. is it lifters or the trunion upgrade?
I had the same problem on a 6.0 that I have.I had asked Comp Cams for help.Mine sounded like a sewing machine.I used longer pushrods to finally eliminate most of the noise.The problem is with the fast closing ramps that are used by Comp. This may be your problem.Comp was not worried about noise,just power.I had it on their forum. Here is a link:
http://www.cpgnation.com/forum/threa...n-noise.21273/
I know that the GM Performance cams are quiet like a factory cam.This is due to the ramp designs they use.However they won`t make quite the power that an aftermarket cam will. Also, part of your problem may be that it was reground? The base circle may be too small,or it could have other issues.I`ve built motors for over 35 years and have never used or recommended a regrind.I have heard too many story's about them.Hope this helps.
newer Gm lifters, ie ls7, have tighter preload tolerances than all the previous lifters... only reason i knew about this is bc i ran into the same issue you're asking about, right after my build. it has nothing to do with the trunion kit, or any of your listed mods. My setup is almost identical as what you're running: 347 ls1 w/ ls6 valves, 1218's, tsp 224r cam w/ 571 lift, trunion upgrade, comp 7.4's, milled stage 2.5 heads... the lifter preload with the 7.4 pushrods was too tight for comfort, for me originally. i checked the wipe pattern on the tips of the valves and actually ended up shimming the rockers with .040 ford shims, rather than getting shorter PR's. i hear many advise against shims on Ls motors, but with the heads milled, ive already compromised the valvetrain geometry as it is... so i'd be willing to bet your lifter preload is set too tight, based on the info you've provided
+2 on the shims if you have too much lifter preload, and your giving up smoother idle/producing less vacuum. On a larger cam, this hurts off idle power when the throttle is stabbed.
Loosen a rocker arm that has its lifter on the base circle, then go less than finger tight to zero lash. Do you need to go more than a full turn to have the rocker tight on the pedestal?