Timing chain question
 

Hey Fellas, I am thinking my timing chain is going bad. But what are some surefire ways to check it without straight out removing and replacing? This is for an 88 c1500 4.3 with probably over 100k miles on the engine.

Before you ask, I believe the timing chain could be bad at the advice of a mechanic friend of mine after explaining how even at 0 deg tdc with the connector off, my truck idles really poorly. But when I advance it over 12 deg it runs like a champ. I have to run for now, but I will get you guys more details as to the items checked and replaced when I get back.

Thanks!

Re: Timing chain question
 

I would remove the spark plugs and dist cap. Then put a ratchet on the crankshaft and turn it either direction while watching the dist rotor. Stop when you see it start to move. Reverse direction and see when the rotor starts to move again. Measure the degrees of crank rotation to get an idea of how much chain wear it has. I dont' know what is normal but think 2 - 6 degrees of crank rotation before the rotor moves would be about right.

Re: Timing chain question
 

Ok, thanks I will do that tonight. But, I was thinking yesterday that the timing mark has not moved since I put it at TDC for years, could a worn timing chain still be a possibility if the mark has been in solid position for years? Maybe I'm wrong about the chain?

Re: Timing chain question
 

I was going to recommend the exact same thing.

You could also have a worn distributor gear causing the timing to walk. I've always heard it to be an issue with the vortec motors but I wouldn't rule it out on the older model. Only way to tell is to pull the dizzy.

Re: Timing chain question
 

So just for clarification, the chain could still be a possibility even though the timing mark is solid?