Re: Head and rockers.
 

I just learned this on my last wrestling match with Cecilia :)

you won't use it every day, but it's a good investment. You can use the same light for all kinds of engines too. Not just trucks. Biggest problem with using a timing light is not getting the wires in the fan blade when it's running. Ask me how I know :poke:

Your noise could also not be the motor at all. Maybe something rattling in the front or on the frame as the wind picks up. Can you do the same thing when you're sitting still and at the same RPMs?

Re: Head and rockers.
 

When cruising at around 55 there is no noise. When i try to accelerate to pull a hill or speed up even slightly the noise begins. Now i hear it when i rev it up to a high rpm in neutral. It sounds like its coming from the passanger side of the engine...ya know the side i have yet to pull the valve covers off of haha. I guess i might know more when i do remove the cover. Oh and does anyone have a know part number for the pcv valves that are under the valve covers?

Re: Head and rockers.
 

This table of known part numbers is very handy. http://6066gmcguy.com/partnumbers.html

Re: Head and rockers.
 

Sounds like detonation to me. Normally that will happen under load when the timing is to advanced and the mixture is to lean and or there is not enough octane. I'd get one of those cheaper lights and just see, Or just retard the timing a bit and see if it goes away.

Re: Head and rockers.
 

How old and what grade of gas are you running? At first you described the conditions for detonation. You could try some drygas as you may have gotten some bad gas. If it persists not only set you timing, pull the plugs read them and check the gaps for erosion.

Re: Head and rockers.
 

No one is giving you an answer. You have two different deals. Its pretty simple.