KB pistons noisy??

[crustodd]

Hey Peeps,
Is anyone else using the KB forged pistons noticing them being noisy/rattly when they're cold, engine not up to temp?

T~

[gradon]

That comes with the territory with forged pistons.

[Muad'Dib]

That comes with the territory with forged pistons.

x2... Silver XJ also experience this with the KB944's ... but it was actually less noise then he expected.

[Cheromaniac]

Cold start piston slap is normal with forged pistons. Right now it might only be slight because of the warmer weather but in the depth of winter it'll definitely be more noticeable.

[SilverXJ]

As Muad'Dib said mine are noisy when cold, but I knew that would be the case. There is less noise than I was expecting. They haven't been through a winter yet so I don't know what to expect from colder weather. I usually let my engine warm up a bit before taking off any how. Just don't put the hammer down until they are warmed up.

What piston to cylinder clearance did your machinist set?

[PolloLoco]

What piston to cylinder clearance did your machinist set?

What clearance should I have set when I take mine into the machine shop?

[SilverXJ]

I used .0040", based on the fact that it is a daily driver, and what my machinist recommended. http://kb-silvolite.com/clearance_pop.php You will never be completly noise free with the forged pistons though. Its not a disturbing sound, the engine just sounds noisier when cold. Also, I don't know if they changed it or not, but the spec sheet that came with my KBs put the quench pad on the wrong side of the engine. You will want to make sure it is on the correct side, which is on the manifold side, away from the cam.

[crustodd]

Hey Guys,
I've realized that they're more noisy now that it's warmer, but the noise that I am mainly hearing is the lifters which are bleeding off from the higher spring rates. It only does it after it's set for long enough for the engine to cool most of the way down for the pistons, or overnight for the lifters. I just have learned to give it a few minutes to warm up and I don't throttle it until it's all the way up to temp. That's a good procedure to follow as a rule of thumb anyway. My machinist didn't use the instructions. He's VERY familiar with the concept of quench and installed the pistons based on the direction that was correct for the build and the combustion chamber shape.

Thanks for the input.

Jeep On,
T~

[SilverXJ]

If you are hearing more noise since it has gotten warmer it isn't the forged pistons.

Since you think your lifters are bleeding down, have you thought about trying different oil filters? I heard that some do a better job of preventing drain back than others.. just a thought.

[Flash]

realized that they're more noisy now that it's warmer, but the noise that I am mainly hearing is the lifters which are bleeding off from the higher spring rates

Just how much spring pressure do you have

Flash

[crustodd]

I can't recall what the spring pressure is. I know that they are Mopar 5.2 v8 dual stage springs. I am using the Napa gold filter. The lifter noise has increase a little with the warmer weather, but the pistons were a little noisier when it was cooler.

T~