scary engine noise update

[Werner R.]

my engine noise is a knocking sound. using the stethoscope, it seems loudest when placed on the numbers 2 and 4 header tubes. the knocking gets louder when i accelerate and softens a lot when i cruise. it is not noticeable at idle. my wife and i both think the knocking is at the same rate as the strobe of my timing light, but this is a tough call. i know this sounds strange, but it sounds like so many beaters i have been next to at a stop light; old cars that have a low pitched knocking sound at idle. i always thought that was lifter knock. i am going to run the engine on seven cylinders, disconnecting wires one at a time, to see if cutting power to a cylinder changes or silences the knock. then i guess the next step is to pull the intake manifold. if i do that can i inspect the lifters and cam lobes?? any thoughts from anyone will be appreciated because i am afraid to drive the car with this knocking; afraid it will blow up on me and throw heavy pieces of metal internally and ruin the engine!!!! am i being a worrywort???
werner

[Tony Alison]

Re: scary engine noise update

It might be worth trying to adjust you rocker arms first. It would be worth a try, unless you definitly think that they are not mis-adjusted.

[Roy B.]

Re: scary engine noise update

May be CARBON build up on top of the piston, As I've said before use WATER .you can look it up on past posting.

[Don Barnes]

Re: scary engine noise update

Werner,pull the valve cover off and look close at the rocker arms where the push rods sit in the little dimple.i have had a noise like you describe on a 350 with a comp cam and hydaulic lifters what had happened was the push rod broke threw that little dimple and at idle no noise rev it and boy it sounded like the piston was cme threw the head kind of knock the push rod gets stuck in that little hole where the oil comes threw the rocker arm.Check on both sides of the engine it will only cost you a set of valve cover gaskets. DON

[Chuck S.]

Re: scary engine noise update

Don, I agree with you...adjusting the valves would be worth the time. From the previous thread, however, I think I remember that Werner has mechanical lifters.

In early 1967, my then-new 66 Impala 327/275 developed a loud hollow knock in the engine. I thought I had ruined it. After studying the chassis service manual, I tried adjusting the valves. As I cranked down on the knocking lifter in 1/4 turn increments with the engine running, the knock just faded away.

[Dave K.]

Re: scary engine noise update

If this is a C2 small block, the rocker covers have a top and bottom. They are not symmetrical. If you have one upside down the rocker arms will hit the cover and make a very loud noise. I know because I experienced this. It is easier to incorrectly install the right side more than the left because the left has the clips for the temp sensor. Remove cover and you should be able to see wear marks if this is the problem.

Dave Kitch
33108

[mike geary]

Re: scary engine noise update

Dave makes a great point. Have you ever noticed the "c" stamped into the lip of the steel valve covers? I've always inferred that this stands for "carburetor" side.

MAG