ok, at low rpm's my motor makes a rattling sound. i have a 305tbi btw. my brother told me it was spark knock and to try better gas. so i did, and that hasn't helped. so i'm thinking that the valves are chattering cuz i've heard people talk about that and they say you can fix it by adjusing them.
is this true?
how hard is it to do?
and would anyone like to tell me how?

thanks

 

at low rpms mine makes a rattling sound too but its just rotted out heat sheilding. If its more like a clicking sound, you could have a sticking valve. Is it a low clunking rattle or more like a knock?

 

like in a straight shift car when you bog it down too much in a high gear and it chatters.... thats what it sounds like. it'll go away at higher rpms, but it seems to be making the sound on a wider range of rpm's now... its getting worse...
i'm not sure how to describe the sound
the straight shift analogy is about the only way i can explain it.
thanks

 

I have the same problem...kinda like a chattering at idle but goes away at higher rpms. I can't find it either but I know it is not spark knock. Spark knock is early detenation due to too much advance (i.e. during WOT). The sound we are hearing is not that. A friend of mine uses an oil additive called "Engine Quiet" from CD-2. He says it helps quiet all those hard to find noises by lubricating all the rings and seals. I think this is a cover-up but it might help till you find out what it is.

 

So, you don't think it might be the valves chattering???

i've replaced the plugs and that didn't help.

the only thing is that it doesn't do it at idle on mine.
just at lower rpms while its moving.... like when it locks the converter at low speeds it'll do it....

but you don't think its anything major???
I hope not