Piston Slap?
 

Ok so when I bought the truck, on a cold start it has a clanking sound much like a sloppy piston, once it is started and running say for 5-10 seconds its gone. Original owner told me that the 454 was notorious for the famed piston slap. Having only had 305-350 SBC I am completely ignorant to the 454. Motor runs great, fires right up, oil pressure is great. Can anyone shed some light on if I should be concerned or this is normal when the truck sits and piston temp is cold.

Re: Piston Slap?
 

I don't know that I would say that it's a big block thing, but it more likely because of forged pistons. They have a bit more clearence when cold and expand more with heat, so they can make some noise at start-up, then quiet down as they warm up.

Re: Piston Slap?
 

Thats what I gathered and it sure seems to be the case. I had just never heard this in any of my other chevy trucks. so shocked you could say i was when i heard it. when you hear a noise like that you heart sinks and you fear the worst.

Re: Piston Slap?
 

Sticky wrist pins will also cause a similar sound. Just warm it up before you load it and it'll live a long time.

Re: Piston Slap?
 

I have done that with all my rigs, i let them warm up some before hitting the road. this sound is much larger then a wrist pin, it sounds like the famous diesel sound for the quick few moments.