Anyone have a definitive test for whether or not the timing chain has slipped on a 429?

I have a 1970 429 4V engine, all stock with 110K on it. A couple of weeks back it just started running poorly, missing at all speeds and real hard to start. I pulled the plugs and found them all black. I cleaned them and reinstalled, checked the cap & rotor, looked for obvious vacuum leaks and refired it. It started up a little easier but that's prob because it was already warm. Idle is extremely rough and when I give it gas it does rev but the engine looks like it's going to jump out of the vehicle. I can also hear it popping out 1 of the cylinders and it definitely sounds like it's laboring.

I put a different carb on it and made sure there aren't any vacuum leaks around it. I also disconnected the vacuum hose at the back of the manifold & plugged it to make sure there aren't any major vacuum leaks. It hasn't changed the way it runs. I loosened the distributor and started changing the timing and when it's all the way advanced the engine will hardly turn over (it's a factory 11:1 C.R. engine) but it still doesn't like to start or run no matter where the dizzy is.

I've run a dry compression test on it and all 8 cylinders are 210-220 PSI. It has a Pertronix conversion kit in the dist and hot coil. I put them in 6 mos. ago and it's been running fine since then until a couple of weeks ago.

I'm thinking the timing chain has jumped a tooth but I'd like to be sure before I tear the front of the engine off. If anyone has a definitive test for determining whether or not the chain has slipped I'd appreciate it.

 

Pull the #1 plug, turn the engine untill #1 comes up to TDC on the firing stoke, check the timing marks to see if you are on TDC, then pull the dist. cap and see where your rotor is pointing.

 

Thanks for the tip. I did some more research on the web and came across an article on diagnosing timing issues where not 1 but 2 "experienced mechanics" diagnosed a slipped timing chain on a Ch*vy motor that turned out to be a cracked distributor cap. Now I've checked the cap several times but I decided to "shotgun" a few new parts at it before I tore the front of the motor off so I went and bought a dist cap & rotor. After I'd installed the new cap and before I tried to start it I inspected the old cap very carefully and I'll be damned if I didn't find a hairline crack running up the side! I'd completely missed it the first few times I'd checked the cap. The new cap made the problem go away completely. So...lesson learned.

 

Good find, the caps a often over looked.