Want some opinions. This knock is weird. It sounds just like the knock I heard when I had a bad rod bearing. The thing is that it's only when my engine is cold. Once it's at normal operating temperatures (180 on my temp gauge), I hear no knocking. So what problems/issues would cause a knock only when the engines cold?

Also, This is my 3rd - 3rd gen Lude B series block that's gone bad. I change my oil every 3K and I am overall meticulous in my maintenance. I do race about 4 times a year. I have intake exhaust and clutch (ACT HDSS) as far as performance mods (think extra strain on engine here...). So, another question...who thinks that an aftermarket clutch (with it's extra clamping force) would cause extra wear on the rod bearings? Anyone with aftermarket clutches care to add?

Atleast I can say that ACT makes long lasting clutches! I'm on my third engine and the clutch still grabs so hard!