knock from valvetrain

[6gunn]

I'm getting knock from what I think is the valvetrain. 3rd gear WOT pull shows 0 knock and I'm running E85 too with the proper injectors/pump to support it. Can the valvetrain "clicking" even trigger the knock sensor? With 1.55 T&D roller rockers & hydraulic lifters, I have the lifter preload at 1/4 turn and suspect that may be too loose. Converter bolts are tight, downpipe isn't hitting anywhere, and both motor mounts are HR parts. Also might mention that it's showing knock while just cranking over the motor(not running) and am running the (I think) LT1 mini starter. Something is amiss and I can't find the source. Thanks.

 

[dynoman]

Make sure the rocker shaft bolts are torqued down . I had one that was loose because the wrong length bolts were used and it pulled the top threads out . The valve train was ticking due to the increased valve lash . I got longer bolts and it took care of the problem .

 

[SPOOLFOOL2]

I'd put my Las Vegas money on a cracked header or leak at the head. Got a stethoscope?
Is this clicking louder when you first start it, or once it warms up?

 

[6gunn]

No stethoscope but I usually use a long 3/8 extension pressed up to my ear. Seems louder when first started up, but the lifters may be bleeding down and take a sec to pump back up. I only drive the car a couple times a month, so there's plenty of sitting. 50psi cold, 15psi hot oil pressure. Doing some reading on here, it seems that 1/4 turn of preload might not be enough...so I think I'll try 1/2 turn and see what happens with the knock gauge. Also, someone mentioned (in other threads) that the lifter bars may be a source of the noise too. Attached is a pic. On gnttypes site about lifter preload, it says something pretty interesting that I never thought of.

More preload will give you a stronger top end and less preload, a stronger lower-mid range.[/quote}

Also with more reading(your thread on clicky comps too), this is probably just the nature of the beast which I'm ok with. Runs great, great power, and all gauges read fine...but just want to find out why this is triggering the knock gauge.

 

[SPOOLFOOL2]

No stethoscope but I usually use a long 3/8 extension pressed up to my ear. Seems louder when first started up, but the lifters may be bleeding down and take a sec to pump back up. I only drive the car a couple times a month, so there's plenty of sitting. 50psi cold, 15psi hot oil pressure. Doing some reading on here, it seems that 1/4 turn of preload might not be enough...so I think I'll try 1/2 turn and see what happens with the knock gauge. Also, someone mentioned (in other threads) that the lifter bars may be a source of the noise too. Attached is a pic. On gnttypes site about lifter preload, it says something pretty interesting that I never thought of.

Also with more reading(your thread on clicky comps too), this is probably just the nature of the beast which I'm ok with. Runs great, great power, and all gauges read fine...but just want to find out why this is triggering the knock gauge.

What lifters? How new are they? Some lifters I've installed quieted down after a few hundred miles. Also putting a little more preload on them can help. At what RPM or MPH are you seeing this knock? What are you reading it with? Scanmaster? Is this clicking sound the same on the left and right side of the engine?

 

[6gunn]

What lifters? How new are they? Some lifters I've installed quieted down after a few hundred miles. Also putting a little more preload on them can help. At what RPM or MPH are you seeing this knock? What are you reading it with? Scanmaster? Is this clicking sound the same on the left and right side of the engine?

I think they're comp(no part number), but hard to tell based off of the engine build sheet scribble. The motor was built in 2013 and has approx 2500 miles, but it was raced hard. The knock is mostly at the top of 1st and throughout 2nd. 3rd is knock free after the gear change. Reading it with the knock gauge and powerlogger. The clicking sounds pretty equal from both valve covers. Since I got this setup back in 2021, I never touched the lash settings. It may have never been re-lashed after it was broken in back in 2013. The coolant was a rusty mess when I got it, so that says a lot about how this motor was treated/maintained by the previous owner who I bought it from a few years ago.

 

[TIMINATOR]

"Clicky Comps" syndrome isn't the lifters. Comp doesn't make their own lifters, neither do the other cam companies.
Comp cams have a quicker ramp rate than most other companies, and that makes more power, but that can also cause lifter noise with inadequate oil pressure, non ported oiling system, inadequate preload, nonadjustable valvetrain with a block that was not square decked, aerated oil from various reasons, and not opening up the lifter crossover passage behind the front cam bearing. The HP front cam bearing has a machined groove on the outside, and although it helps keep the drivers side lifters oiled, it's not enough.
On a turbo motor, the cylinder pressure is much higher and it pushes on the exhaust valve face collapsing those lifters under boost. That can be the click after the RPM/ boost comes back down until the lifter pumps back up.
Some of us run much more preload so if the lifter does collapse, it won't be as much. Typical Hydraulic lifters have between .100 and .128" travel. If you realize the difference in duration at advertised (.006") and .050" is around 50 degrees, and with .025" preload you have another .100" of plunger travel below!
Think of what duration and lift you can lose! Remember that if the lifter "only" loses .050" you need to multiply that by your 1.55 rocker ratio to know what lift the valve is actually losing!
TIMINATOR

 

[BEATAV8]

heavy knock signal during cranking is normal.
Valve float gives off a knock signal too. May need some more spring pressure.
Preload shoot for .040”

 

[SPOOLFOOL2]

I would definitely put a little more preload on your lifters. That should quiet them down a little, if that's what's clicking. When you mentioned "lash". That would be if you had a solid (non hydraulic) lifter. I don't believe that is what you have. So we're talking about preload, or compressing the lifter in your case. Even if you quiet the lifter down a little, I suspect that you still may be showing knock (KR) or false knock in first or second gear. You can chase your tail on this forever. If you have a Turbotweak chip, Eric can put a knock ignore for the 1/2 shift, as this event, plus wheel spin and drive shaft vibrations can set things off. Also, keep in mind that at the 1/2 shift, you're not loading the engine very much. Where you want to keep an eye out for knock of bigger concern is at peak torque in 3rd gear. This will most likely be around 80-90 mph for a stock to mild build. As you "tickle" this 3rd gear area and see knock, it should come on slow, then go away as you pass through peak torque. This is provided you have enough fuel and everything is running proper. False knock down low, usually shoots to a high number right away. Make sure you don't have a downpipe hitting the frame, bad motor mounts, or other issues. Post up a Powerlogger file here if you can.

 

[TIMINATOR]

On our performance cars and Harleys
(the HDs use upperend oiling restricted SBC hydraulic roller lifters), we set the preload up from solid on the bottom about one turn or sometimes less. As the engine warms up, the preload lessens as the heads and cylinders " grow" away from the crankshaft anyway, so no issues. This works well on all motors, but especially well on aluminum head motors, and cylinders too on the air cooled HDs.
On a built up HD making above 100 hp, running the lifter "deep" nets as much as 5-7 HP, and that's only 2 cylinders.
NHRA checks to make sure that you are not running solid lifters on a stock eliminator engine originally equipped with hydraulic lifters, after record setting or winning passes.
So to set records or win, the lifters are first filled with 90 or 140wt gear oil or 50-60 wt. Harley or aircraft oil to minimize bleed down, then run long enough after the pass for the thick stuff to wash out before tech impound. But you didn't hear that from me......
TIMINATOR

 

[SPOOLFOOL2]

Also. An old trick we used to do. Not sure if others are still doing this.
Put two or three wraps of Teflon tape on the knock sensor, then crank it down hand tight.

 

[6gunn]

Also. An old trick we used to do. Not sure if others are still doing this.
Put two or three wraps of Teflon tape on the knock sensor, then crank it down hand tight.

Does doing that make it less sensitive? Since I'm running E85/125#/525lph and the fuel system is up to the task, would it be a bad idea to just unplug the knock sensor? Max boost for the chip is set at 30psi from a 6466BB, fwiw. I plan to check/set the preload later today...

 

[TIMINATOR]

Yup. That was an old "trick" back in the day, until peeps discovered it was better(cheaper) to find the knock than replace bearings or rings.
If you really want to find out how much HP you are losing with hyd lifter bleed down, install a set of solid rollers on your hyd. Rlr cam lashed at .005" and make a few dyno pulls or passes. Or lash it up a half turn from solid on the bottom. I ran my 1984 Vette that way with one of the first Crane Hydraulic roller cams sold. That was before slow bleed lifters came out. The 222/230 hyd rlr slowed the car by almost a second and 8+ mph from the stock cam, as the kit had 175+ lb springs with it, we now know thats way too much, especially for lifters of that day..... With solid lifters it picked up to around .7 and 8 mph over the stock cam.
Don't assume it's false knock, it could be that and real knock at a higher load.
TIMINATOR

 

[dynoman]

Do a third gear WOT pull and immediately pull plugs and check for signs of detonation and lean or rich conditions . I heard stories of motors being blown up on the dyno and nobody thought they should check plugs .
This can help ease your mind on false knock .

 

[TIMINATOR]

X2

 

[THensley]

You said knock at cranking , Cracked flex plate ?

 

[6gunn]

I didn't see any cracks in the flexplate when I assembled everything a couple years back, and also when checking the converter bolts...but no telling whats happened since. I got everything set at 1/2 turn preload instead of 1/4 and can tell a difference in sound. It's quieter at idle...not by a whole lot, but enough to tell...but unfortunately found a fuel leak that prevented me from taking it for a test drive until I get the parts in.