knocking noise

[SmallsTX]

So my 81 k10 has recently started knocking, any idea what it could be? its a 350 sbc

heres a video

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[fast 99]

Get a stethoscope from RA. Is it from top end or pan, louder or quieter under load?

Drain oil any metal?

Could get an oil analysis but that will take a week or so.

Try pulling valve covers and look for loose rockers.

These are just suggestions to narrow down.

 

[SmallsTX]

no oil or metal from what i can tell, when rpms go up the noise seems to simmer down a bit, ive got valve covers pulled now. just trying to figure out if i need to redo all the rockers and go from there or just send it to the shop. to be honest it sounds like it could be bottom end, someone said could be the fly wheel?

 

[SmallsTX]

Get a stethoscope from RA. Is it from top end or pan, louder or quieter under load?

Drain oil any metal?

Could get an oil analysis but that will take a week or so.

Try pulling valve covers and look for loose rockers.

These are just suggestions to narrow down.

how tight do the rockers need to be?

 

[squaredeal91]

Hard to tell from video, i can also hear an exhaust leak/flap. I once boughta square for cheap once because the guy thought it was knocking. Had headers i changed that side exhaust gasket in napa parking lot on my way home lol. I hear the sound in the video
but hard to say. Does it quiet when idling in gear? Quiet when you start it up in the morning and progresses as it warms?

 

[squaredeal91]

There's another recent thread that touched on Rocker arm adjustment on like page one or 2 of it. Can't remember the name. Maybe I can find it again.

 

[squaredeal91]

I have know idea how to share but it's called

What zero lash on the lifter rod should feel like?

 

[fast 99]

If exhaust leak, piston slap noisier cold. Rod quieter cold. An exhaust leak can be easily diagnosed with a stethoscope.

If a valve has excess lash that is usually a sign of wear or loose adjusting nut, try to rake any lash out as described in previous thread.

 

[JBswth]

So my 81 k10 has recently started knocking, any idea what it could be? its a 350 sbc

heres a video

xc_hide_links_from_guests_guests_error_hide_media

Sounds more like clattery lifters than a knocking sound.

 

[JBswth]

how tight do the rockers need to be?

With both valves on a cylinder closed, and the lifters on the base circle, the rockers should be 2 turns tighter than zero lash, assuming that your hydraulic lifters are good. Best to set them with the engine running and warmed up, that way you will be able to tell if a lifter is stuck, as the cylinder you are working on will start missing when you make the rockers any tighter than zero lash if that lifter is stuck.

Mike