I've had good luck with engines lately but on a recently rebuilt 406 sb, I can't seem to eliminate valve train noise. It's pretty loud...not a tick. I've adjusted the rockers both cold and hot, which eliminates the noise temporarily (5 or 10 minutes) but the noise returns. It's not one rocker/lifter,..it sounds like two or three or more.
The engine/valve train:
AFR 195's, 74 cc (new heads)
AFR valve springs; 120# at the seat, 310 open
Magnum 280H cam, 230 @ 50, .480/480 lift
Comp hydraulic lifters
Comp hardened 5/16 push rods
Comp roller tip rockers
Comp poly locks
The initial break-in...the engine fired up at the touch of the key. I followed Comp's break-in instructions perfectly with two exceptions. I didn't remove the 'inner' valve spring. I was told by two respected engine builders that this was unnecessary with my mild spring pressure (stated above). Secondly, 10 minutes into the break-in I shut the engine down because she was approaching 230 degrees. I waited 30 minutes, and resumed break-in...2000-2500 rpm for another 10-12 minutes. Water temp stayed around 210 on the second go-around.
I did use the Comp lifter break-in lube,..the little packets, though I didn't think much of it...it seemed slightly more viscous than 80 wt oil...in other words, I'm sure most of it drips away. The cam was lubed with a better-looking assy lube...the gray pasty-looking stuff. The short-block was built by a machine shop,..I did the top half of the engine and install into the 69.
The chatter started about 5 minutes into the initial break-in and at the time I didn't think it much of a big deal.
I did see weird fluctuations in oil pressure during break-in...both high and low...15-70 PSI, but I reasoned that the break-in/assembly lube(s) were causing this. Pressure is steady and strong now after an oil change.
But I can't seem to eliminate the clicking...also, the engine runs poorly. I've built this exact (almost) combo before and I know it should have twice the power she's giving me now.
I've ruled out the follwing:
1) Guide plate misalignment...they're fine...rocker tips are nicely centered over the valve stems.
2) Oil not reaching the valve train...it is.
3) Bent push rods...I checked a couple
4) Poor rocker to valve stem geometry..it's good
5) Poly locks coming loose...they're good and tight.
6) Header leak (this has fooled me before)
7) Loose rocker studs...all 16 are torqued to specs with red-loctite.
My most recent adjustment, I cold adjusted by bringing each piston to TDC (following compression stroke), feeling for zero lash, then a 1/2 turn on both rockers. In other words, the valves were adjusted with the lifters on the base circle.
But, the chatter returned before I pulled out of the driveway.
The chump is stumped, but thinking the worst...a lobe or two has been scrubbed off.
Any other ideas before I jerk the engine?
Thanks in advance!..and sorry ofr the long post.