I have your answer gentleman that noise you arr hearing is the computer adjusting the ignition timing to prevent knocking and pinging and damage to the pistons and bottom end.

 

thanks for you post, has really been helpful in finding out what might be possible causes, will look into those when get truck in when gets warmer. About the truck we purchased the truck for really cheap, had sat a while before we got it. looking at the engine we believe the engine not to be original almost looks like a junkyard engine, that has alot of smog stuff taken out. not sure if vacuum lines are run right or not. Only thing we have done so far has been to replace the carb. The distributor looks like its new, and we replaced the sparkplugs.

 

it runs and drives, the 4wheel drive works, and at idle it sounds really good, just when you rev it up it sounds poppy. Hopefully it dont take much work, or much money to fix. Id hate to have to use my whole tax return on having the engine rebuilt.

 

I had the same problem with my truck when i bought it about 7 months ago. It sat for a long time before I bought it and would POP when giving a lot of gas. I do not know how long you have had your truck for, but if it had sat for a long period of time the popping noise might just be bad gas. After 6 or 7 tank fulls, my popping went away. If the engine is not original, or the smog equipment has been removed, the cause could be many things. Best of luck, please update if you find the cause.

 

The popping is no more we recently replaced the timing chain. when we tore into it one side of the chain was loose and the cam was 180 degrees out.