Yes I saw that last night and am pretty certain this is where I'm at. Just don't understand why it was happening longer at times. It's a new thing...
I just pulled the truck around the block to back it in the driveway. I'm leaving for a couple of hours. It started with the 2 second taps ... Not liking the idle as much. Seems nervous...tiny missy feeling... Everything is really quiet...not tapping....sounds good.
There is a weird resonance sound coming from #6 area when I put my hose and listen right on the valve cover. Seems new to me... It's very subtle....Almost like if you took a microphone feedback and pitched it down a little and gave it rhythm like the lifter..
Strange....
But no tapping or ticking....Maybe more of a sewing machine symphony.... Not as quiet as I've heard it before but definitely nice enough.
I do think I'm going to try 1 more attempt at a hot running adjustment. Maybe I'll get lucky and the long startup taps will stay away.. Because I really felt like the engine liked where it was at before apart from that tapping......and I don't feel super confident I got zero lash right using the cold method...Not that I feel confident with either.....
There's a combination somewhere....
Good status report. One thing that you wrote recently that I wanted to comment on was
when you performed an adjustment on the valves and you found them all to be pretty much at a
1/2 turn, I thought that this was a turning point for a couple of reasons. First, it demonstrated to me
that you have acquired the necessary technique.
By the same token, if you perform a good running adjustment but some noise remains, then
this might cause you to incorrectly lose confidence in your adjustment. (!) As a matter of fact, *this*
is what motivated me add the info about the noise from the external wear and/or internal varnishing
information to this thread.
In English, we were hoping to use what the factory has in place to adjust all brand new parts to the midrange
of their travel. And when this technique fell short on used parts, for someone new to all this it makes sense that
it can cause you to doubt your adjustments.
So yeah, if it was me I would take my time, make one more running lash adjustment,
get everything as quiet as it can be. And then drive it. And then if it's not totally quiet,
then I would first identify all of the lifter assemblies that ARE quiet, and document that
carefully. And the remaining 1 or 2 lifters that are still noisy could be identified as the ones
that get pulled when the intake re-gasketing is accompished. And if they
fail a visual
inspection, then take photos, put them right back in, put the intake back on, and head
straight to the aforementioned "
Decision Time".
But if the noisy lifters
pass the visual inspection, then go ahead with the disassembly / clean
/ reassembly / pump up / test / reinstall / reset lash ...and see if you now have the quietest
valvetrain of any SBC of similar vintage and accumulated mileage? To me, this is the very
definition of a Measured Response. (!)
Hmmm...so no number 3.5? Replacing lifters and maybe cam ...sorry if it's obvious why not......
OK, just new lifters is best explained by the first illustration in reply #93. (
New lifters on old cam)
Because we are dealing with 200-300,000 PSI, the geometry where the lifter meets the cam lobe
is *critical*. Therefore, new lifters on an old cam lobe that just tore up the original lifter is
the scariest,
most failure-prone very failure prone.
EDIT:
1) Used,
concave lifters on a new cam is the most failure prone of all.
2) Used lifters jumbled up so that they don't go back onto the same cam lobe they wore into is very failure prone.
3) New lifters on an old cam is the best of these
NOT-recommended practices, for at least the lifter base is
convex.
4) New, offshore 'white box' lifters are failure prone. Questions of poor machining, manufacturing debris inside lifter body, and improper heat treating.
5) Excessive spring pressure is failure prone. Lower pressure beehive springs that can handle the valvetrain is preferable to stiff double/triple conventional valve springs.
6) Many report that the new Delphi hardened base flat tappet lifters with a stock GM cam & stock spring rates gives you a better than average chance of success.
7) Comp Cams has a new DLC (Diamond Like Carbon) coating that has survived extended Spintron abuse and may be a new solution: (
DLC and Dragzine)
--
8) Upgrade to LS7 roller lifter and compatible roller cam if block was cast/machined for the roller cam option.
****
And whenever you hear about a new cam & lifters going into an engine and actually working,
this is due to the new parts being installed as an upgrade, so the old (stock) cam was in perfect
condition when retired, so there wasn't any hardened metallic debris inside the engine, and all is good.
On the other hand, when a cam & lifters fail inside an engine, and the scope of the repair is only to replace
the cam & lifters, then all the debris left inside from the failed cam causes the cam bearings, main bearings,
and rod bearings to wear to the point where the oil pressure starts to drop off, and a death
spiral ensues. There are countless examples of this happening, and lots of tears shed over the
initial failure, compounded by the following repair attempt failing yet again.
This is something that only a misled owner (who really wants a long term fix) or a person who's
planning on getting rid of the vehicle immediately afterwards would consider doing. (ie: Unethical flipper)
Note: I've been asked in the past to put the quick fix on a noisy motor like this, and I've always refused
the invitation to get involved. It ain't right.
I think it'll be ok... I'm going to keep an eye on everything and of course read through everything and spending time with the added links and files.
This has been a good conversation. 99% of the time a SBC cam discussion is focused
on just how much bigger or badder a bumpstick can be installed. But here we are discussing
at length how to adjust a cam for best valve seating, quietest operation, and longest
service life.
I'll keep digging. More later.
PS: You know, we've been talking about counting threads. And if they are the HD screw-in
studs, then their installed length is a given. But on a lot of stock small blocks, the rocker arm
studs are simply pressed into the cylinder head. And sometimes they will start to pull out
but still be working. (See attached for the clearest picture I could find on the internet showing
a pulled rocker arm stud.)
In English, it would be a good idea to place a long ruler or straightedge across the rocker arm
studs in order to make sure that they are all at the same installed height. Based upon your
photos I don't think that you have this problem, but it only takes a second to verify and then
we have that much more confidence in our cross-check.
And if I have to choose between matching thread counts or quieter, smoother running? I
prefer the latter in all cases. Let the engine tell you what it wants with the running adjustment,
and then we'll figure out what the details mean after the fact.
