I was doing a few hard runs to test a new PROM. Afterthat I drove the car a half mile normally. It drove fine. Stopped it. Restarted it a minute later and pretty much let it idle about 20 ft, at which point it started knocking
This was pretty much an instantaneous thing and I wasn't even giving it gas. I'm really hoping it is some other part of my valve train. But in reality I know its not!

So your question is what?

It can happen in a small enough amount of time you cant measure it.

It *may* be a lifter. Try to find out if the noise is from the bottom end or top end. Bad exhaust gaskets make a tapping noise, dont know how bad the noise is on your car.

how do you know its not? is it distinct? knocking can be many things. why would go get rod knock because you stopped and restarted it? i am lost on that one. knocking can sometimes be cracked/broken flex plate. timing chain?

hope its not your rods/crank

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87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake slp 1 3/4 headers accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

http://people.ne.mediaone.net/gdm

I had a rod knock go from very queit, barely audible, to 3 spun bearings and 6 broken piston skirts in about 3 hours (long story). It souned like......It was indescribable. If you think you have a rod knock, have it checked. An experienced mechanic can tell the difference MOST OF THE TIME.

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92Z28
89GTA

See thats why I am holding out there is a slim chance it's something else. It didn't slowy increase. It came on loud enough to hear in the car immediatly.
I pulled the valve covers and didn't see a mis-aligned rocker. But I am so depressed I haven't looked at it again and don't want to. My car has been constant problems for too long.
In fact I was on my way to get the slipping tranny rebuilt when this happened.