motor trouble

[Tstates]

I recently posted my success with getting my 78 trans am- 400 to run nearly perfect with the HP carb tunup and mods.  I went out today and got on the gas hard through about 5500 rpm, when I let off I got some back fire noise and what sounded like a header leak.  I pulled over and could hear the engine running a little rough and I can hear some top end knocking noise.  I also noticed that my oil psi is now showing 20-45 psi, it use to stay at 40-80 psi.  The engine got me back home,  had plenty of oil and had no increase in engine noise.  My 2 cents is I bent some lifter rods, but why did my oil psi drop?
Any input would be greatly appreciated.  In any case I plan to pull the heads and start there.
Thanks again.
Thane

[Toronado]

Seems hard to pinpoint the damage that occurred,
without more testing and test results. If oil pressure
dropped that far there is a major problem, it screams
rebuild. My 2cents

[jamesF]

Dang.. with the low oil pressure and the noise....yeah.... may be a bearing issue.... Might save yourself some trouble and pull the vave covers.. Inspect for bent pushrods, loose nuts, rocker that slipped off the valve... etc... If you dont find any of that.. You should get to the bottom end and pull rod caps and main caps...Pulling the heads likely wont reveal anything further.

Anything that you might find pulling a head off likely would have been catastrophic... but you got home ok...


... Let us know if you need any help..