89 305 engine knock........help

[Olds442455]

Hi,.
I have a 89 firebird with a 305 tbi..
When I put the gas to the floor some times I hear a litle knock,knock in the engine and then I get a litle puff of smoke out the rear....At the moment this hapens it feels to have no power and then all of a suden it will pick on up and take off as normal with no smoke.
It also gives me a a nice puff when I nail it hard..

I know the valve seals are gone for sure at 108,000 but if I need a set of rings due to the smoke when I nail it could they (the rings) also cause the knocking sound I am hearing when I take off at lights or slow down and speed up rounding corners,,. Just when I first accelrate then it clears out.... Any one had this type of problem??

Thanks for any help..

[95fbodyunder3k]

never had this problem every time my cars develop a konck they dont last long but any way what color is the smoke gery black or blue but yer right the rings can give a knocking sound but make sure the car is timed right look at the plugs and see if they are clean and white or if they are dark and even try a higher octane gas it could be spark knock or your car is loading up with fuel

[scott388]

possible wrist pin (s)
probable thurst bearing and rear cap bearing wear
oil psi is still enough to fill the space when u get it reving sounds like
that's why the knocks becomes unaudible
(it's still there though)