How to tell if timming chain skipe or streatch to mutch on 1982 gmc 1500 automatic with a 350 engine.I have good compresion on all pistons .

The 80s were not good for GM, If you think it has jumped time then it probably has, The 305s and 350s made in the 80s had a cast aluminum cam gear with plastic adhered to the teeth so the chain wouldn't be "noisy". The plastic wears down and the chain gets loose and jumps time. Every one I replaced had between 105,000-120,000 miles on them, And I've changed a lot!! As far as compression, the valves are still going to open and close, just not exactly when they are supposed to, So you will still get a good compression reading on the engine. Good news is all the new aftermarket timing chain sets sold for that vehicle are made of steel, If you go to the dealership they will probably still have the plastic one in stock. I hope this helps, Good luck

Thanks a lot I will change the chain and gears I'm glad to know that I'm not the only one that think that what my problem is and I will go with after market if they are made of steel and no plastic.
I appresiate you taking time to answer me and mabe all be able to help you in the future.

I change the timming chain and gears now the timming is perfect but the truck won't run to good it has no power and I have the idlle wide open to keep it running it sounds like its suching way to mutch air in the carb sounds like a big vacuum cleaner in the carb any idea of what the problem could be on this 1982 gmc with a 350 engine.
Thank you in advance for any reply.