[ThicZL1]

So I currently have a dilemma that has me lost. 2010 H/C/I/E, pullies, ported blower, ZL1 lid, forged rods and pistons. I hear a noise in the top end and take it apart to inspect. I pull the blower belt and notice the noise is still there. I pull valve covers and I see nothing out of the ordinary, pushrods are straight, springs are good ( BTR .660 duals with ti retainers ). I see on the build sheet it has LS7 lifters so I dive in and throw a new set of lifters in. Pushrods currently are 7.400 BTR units. I get the car back together and the noise is still present. I have no misfires, perfect oil pressure, zero performance issues with the car. I just have this God forsaken noise everyone swears is a lifter. I have fresh oil with less than 100 miles. I double and triple checked exhaust bolts and bands, tried pulling plug wires tonsee of there is a tone chnage. Nothing.

People say they're noisey, people say the engine materials with thin wall long tubes makes the noise worse. I have the noise local to one spot and will add pictures and videos and specs. Where the F do I stand. I am to the point of pulling the engine.

Forged rods and pistons
King bearings
Millings HV oil pump
Vengence VRPD-2 231/239 .617/.624 118LSA
Btr 660 dual spring kit
7.400 pushrods
2.55 upper
9.1 lower
BTR trunion upgrade
FIC1050 injectors ( pump gas )
Ported LS3 heads
Ported blower
ZL1 lid
Killer chiller
New Ear 4.5" intake

The red.circle represents the only place I can hear an auditable noise with a scope.

 

[RedTXV]

You’ve obviously done your due diligence on diagnosing, wish I could help. I’m just a local greeter.

We’ve got some pretty smart guys here. I’m sure someone will come along to offer some assistance/suggestions.

And welcome!

 

[Heavymetals]

Does the noise go away anytime?

With a cam, there is a chance that a pushrod will hit against a wall, you can remove those points with a Dremel.

Inspect the pushrods very carefully and look for a wear mark.

 

[loweredd]

Does it change with RPM?

 

[Blown376]

I was hoping to hear the typical valvetrain noise or sewing machine injectors, but this is something different.

 

[Heavymetals]

I was hoping to hear the typical valvetrain noise or sewing machine injectors, but this is something different.

Timing chain/sprockets/tensioner related?

Last resort, start it with the accessory belt off.

Determine that it is the motor.

 

[Blown376]

Timing chain/sprockets/tensioner related?

It's pretty rhythmic, waiting to hear from OP if it changes with rpm.

 

[theheder]

If varies by rpm could it be SC rotors?

 

[ThicZL1]

So it changes with rpm, but is only prominent at idle to 1500rpm +/-. I pulled the blower belt and the noise stays with the engine. I have not pulled the accessory belt but I believe it's so localize with the engine I can rule that out.

 

[RocketSled]

Harmonic damper or timing chain tension. Remove belt and see if the sound goes away. The blower turns at a higher speed compared to engine RPM, it's geared up. If it was banging it'd be a faster rate sound I think.

Oh, just saw your update. If it stays with the belt removed, it's not the blower. If it still sounds like it's coming from the front of the engine, it's none of the accessories, that pretty much leaves the timing chain tension. Tensioners do shit the bed, in my experience anyway.

 

[ThicZL1]

Harmonic damper or timing chain tension. Remove belt and see if the sound goes away. The blower turns at a higher speed compared to engine RPM, it's geared up. If it was banging it'd be a faster rate sound I think.

Vehicle has a brand new ATI balancer as well.

 

[RocketSled]

Oh. But it still made the sound without the belt so it's not that, anyway. Without the belt, besides the ends of the crank and camshafts, the timing chain is the only other moving component on the front of the motor.

 

[ThicZL1]

Oh. But it still made the sound without the belt so it's not that, anyway. Without the belt, besides the ends of the crank and camshafts, the timing chain is the only other moving component on the front of the motor.

I don't want to say I'm confident it's not the chain but, only because when I scope the cover I hear nothing but what a chain should sound like no auditable or harmonic knocking/tapping. I can get another video today ( I'm working emergency shift at work from 2a.m.-2p.m.)

I have had so many people tell me it's a lifter and I'm trying to convince myself maybe it's a preload issue but at the same time it's hard to tell.

 

[jcs003]

Take out push rods and measure them. Also look for witness marks on the rockers to determine if one is 'slapping'

 

[Corsair231]

Have you checked your oil pressure? I know you said you put new lifters in it but maybe you're not getting enough oil pressure to fully expand a lifter until your rpm picks up. It was on an LS4, but I had one lifter that would tick at idle but not at speed. It ended up being the o-ring around the oil pump pick-up. It had gotten brittle and was letting air by and it would drop the oil pressure enough to starve the one lifter. Replaced the o-ring and the tick went away.

 

[ThicZL1]

Have you checked your oil pressure? I know you said you put new lifters in it but maybe you're not getting enough oil pressure to fully expand a lifter until your rpm picks up. It was on an LS4, but I had one lifter that would tick at idle but not at speed. It ended up being the o-ring around the oil pump pick-up. It had gotten brittle and was letting air by and it would drop the oil pressure enough to starve the one lifter. Replaced the o-ring and the tick went away.

OP is 75 on a cold start and drops no lower than 30psi at temp at idle.

 

[Heavymetals]

When you do a cam a problem can be in the preload, especially if you use the same length pushrods.

Unless you measure this correctly, you can have too much preload and that will make noise.

You want just enough preload to get the lifter plunger off the retaining ring. Let the hydraulics do the rest.

Also, some high lift cams reduce the base circle which really screws up the geometry.

That allows the lifter to drop past the bore and fulcrum against the bore edge.

On the cam upstroke the lifter bangs against the bore.

SWELL huh?

 

[Corsair231]

Shouldn't be oil pressure then unless you have a single lifter oil feed passage restricted which is not likely but with the sound going away over 1500 rpm, it sure sounds like it would be pressure related or possibly preload set wrong. If it was a clearance issue with something hitting, it shouldn't go away and 1500 rpm shouldn't be so fast that you couldn't still hear it.

If you have taken it apart enough to replace the lifters and made sure the reused parts were good and installed correctly and the sound is unchanged, then it has to be something you haven't touched yet. I know you said you have taken the supercharger belt off but did you ever take all of the belts off? Eliminate all of the accessory movement and the only thing you can be left with is internal.

By the way, is this a new build or is it an older build that has just started the tapping?

 

[ThicZL1]

When you do a cam a problem can be in the preload, especially if you use the same length pushrods.

Unless you measure this correctly, you can have too much preload and that will make noise.

You want just enough preload to get the lifter plunger off the retaining ring. Let the hydraulics do the rest.

Also, some high lift cams reduce the base circle which really screws up the geometry.

That allows the lifter to drop past the bore and fulcrum against the bore edge.

On the cam upstroke the lifter bangs against the bore.

SWELL huh?

I knew this cam was massive, but I didn't think it would start causing a noise over time. The lifter bores ( from my " trained" eyes ) all felt good and I've sure the lifter slid in and out smoothly without any interruption. I guess I'll double check pushrod length and see where that gets me.

 

[ThicZL1]

Shouldn't be oil pressure then unless you have a single lifter oil feed passage restricted which is not likely but with the sound going away over 1500 rpm, it sure sounds like it would be pressure related or possibly preload set wrong. If it was a clearance issue with something hitting, it shouldn't go away and 1500 rpm shouldn't be so fast that you couldn't still hear it.

If you have taken it apart enough to replace the lifters and made sure the reused parts were good and installed correctly and the sound is unchanged, then it has to be something you haven't touched yet. I know you said you have taken the supercharger belt off but did you ever take all of the belts off? Eliminate all of the accessory movement and the only thing you can be left with is internal.

By the way, is this a new build or is it an older build that has just started the tapping?

So this build has less than 7k miles on it. I would have to check the mileage to be accurate. New block / crank /rods / pistons and wrist pins, new. Yes, this has started making noise over time. Oil changes were religious, warmup times were respected, and I'll be 100% honest I haven't even taken the car to a track so abuse was ruled out on my end.