"True Roller" double timing set make more noise?

[Cobra4B]

Is it normal for a "true roller" double timing set to make some noise? Trying to diagnose a tick on my father's Panoz. It has a carb'd 347 stroker. The engine has been gone through and rocker arm preloads all set and re-set. Got new lifters and freshened heads when it cracked a vavle spring a few months back. Prior to that the engine had been fully rebuilt and was as new. The engine has a steady tick from the front center of the motor. Screwdriver on the valve covers doesn't show anything clear, but when I put it on the intake manifold I can hear the tick. Shop said they're certain the engine/internals are fine and that it's the timing set being noisy. I don't know enough about SBFs to evaluate if it's normal noise or an issue. Has comp pro magnum roller rockers too.

 

Thanks,

 

 

Brian

[UBR]

We have three of those 347 Boss blocks for our 2 cars. The only time we have had valve train noise is when a hydraulic lifter is bad (or oil pressure is low) or the valve adjustment is wrong. We switched to solid lifter cams last season. We run double roller timing sets and they don't make any noise. Certainly not a tick.

 

I would bet it was a lifter if you're running hydraulics. Especially coming from the "middle" of the engine. Valvle adjustment sounds like an old Singer sewing machine coming from the valve covers.

 

j

[Cobra4B]

I was going to say lifter as well, but they're new lifters.

[UBR]

We switched to solid lifters because we have had hydraulic lifters fail 2 years in a row at nationals and take us out. I'm sure someone makes a decent hydraulic that can hold up to our rpm and duration levels but all 3 motors have had problems until we went to solids.

 

I'd make sure you have decent oil pressure and pull the valve covers with the motor running. Often you can feel a weak lifter by grabbing the rockers. The one with the tick feels different. If a lifter has completely failed, there will be a lot of lash when you spin the push rods with the motor off.

 

j

[Cobra4B]

Here's a video with the passenger side VC off. I've never started an engine with the valve cover off. Should oil be squirting out of the pushrod vs. dribbling out? Motor has a high volume pump on it and 20w50 Joe Gibbs racing oil. Oil pressure on the gague inside says 48-50 at idle and didn't change when rev'd to 1500ish.

 

[UBR]

Yes. Oil will splash out of the rockers and onto the headers. It's usually not excessive, but makes a mess.

 

You have plenty of oil pressure. I definitely hear the tick. It's hard to tell a weak lifter by look. It's a feel thing. I grab the rockers between my fingers and push on them at idle. The weak lifters have a different feel.

 

It may be the level of audio, but it doesn't sound like a classic lifter noise. It's more of a metal clink or tick. But it's definitely rpm based. Possibilities go from simple to stupid at this point. I have never heard a newer timing chain make that kind of noise though.

 

Sorry for the lack of help. The video sounds more metallic than a lifter typically does.

 

j

[Cobra4B]

I'm pretty sure it's piston slap now... ran it a few times with both VCs off and the noise is really center of the motor. I checked all the pushrods with the piston at TDC and none of them are loose and no indications of a soft or collapsed lifter. Listened to each rocker arm with a screwdriver on it and couldn't pinpoint anything. So, overall I think it's a noisey valvetrain from the cam, double springs, and comp pro-magnum rocker arms. I will say that the noise wouldn't phase me for a second with a LSX as most all of them have piston slap. My Z06 starts up quiet, then starts to tick as it warms up, then it goes away and all is well from then on.