My daily driver is a 79 caddy with a 425. It doesn't knock as soon as I start it, but starts after a few minutes and seems to be loudest at idle. The knock doesn't get worse as rpm's increase, but it doesn't go away either. The car has been doing it for about 6 months and it seems to be slowly getting louder. Rod or lifter? Which do you think?

Thanks,

Loren

 

How loud is the knock? I'm thinking spun bearing. (CRANK). If it doesnt knock when you start it but when it warms up it starts......thats my guess. Sorry I'm sure you didnt want to hear that.

 

It is pretty darn loud...enough to be embarassing at a Bank teller window. Not obnoxiously loud...just audible...does that makesense?