Can't figure out timing... I'm at a loss..

[Evil Bird]

Little background. Bought a basket case 66 Coronet with 383 & 4 speed. It's been sitting years, who nows how many. Changed the oil, pulled the distributor (marked location of housing and rotor) then primed it. It started right up, smoked for a hot minute and cleared right up. There was no hesitation and revs quickly. Sounded fantastic. So, we worked for a few months on brakes, steering components, fuel tank, etc. Got the car ready for quick test drive and it ran like crap. Bogging at idle with giving it gas, it was un-drivable. So had adjusted the timing to ear and got it close enough where it would idle and rev well with just a little hesitation. Put the timing light on it and it doesn't even register on the timing pointer. It is about 4 inches away from 0* BTDC. Did it skip a tooth some how? I'm at a loss.

 

[AR67GTX]

That’s possible. I had an old Mercury 351 that did that. The timing chain was really stretched in it and hanging low.

 

[PurpleBeeper]

Maybe you "skipped a tooth" if you have plastic gears on the upper timing chain gear and the got worn. However, I wouldn't jump to that conclusion. How old is that is that gasoline? Maybe put in fresh gas and try to reset timing using the timing light and the vacuum advance blocked off. Start from something you know for sure and go from there

 

[Mr. Mike]

I'd check the harmonic dampener whilst you're at it.
The elastomeric binding could have failed allowing the outer ring to move in relation to the hub.
Also a breaker bar and socket on the dampener bolt and dist cap off turn the crank CCW see if rotor moves.
If you haven't changed rocker cover gaskets turn the engine w the socket watch the #1 rocker sequence to get into the TDC ballpark then check timing mark again.
Be on the safe side replace the timing set and dampener.

 

[Don Frelier]

You should verify if the harmonic balancer slipped first.
But yes it would seem as though the chain jumped.
They run but have zero power until they get up in the rpm range when the chain is jumped.

 

[zyzzyx]

Do a "Pop your finger out of the number 1 spark plug hole" trick and see how far it's off. Check the 1-8-4-3-6-5-7-2 firing order
and then try and determine if the balancer has spun.

 

[ykf7b0]

How's the carb?

 

[moparedtn]

Wait, just so we're clear here....
The only difference to the engine itself between the time before, when it "sounded fantastic"
and now, when it's running like poop......was some time passing?
You didn't do anything to the engine itself during that gap in time at all?

 

[AR67GTX]

That old Mercury seemed to occasionally skip a tooth upon starting. Once started the chain pull on the cam gear seemed to keep everything engaged OK. I got by the first time or two by resetting the timing but that only got me by for so long until it would barely run.

 

[Evil Bird]

Wait, just so we're clear here....
The only difference to the engine itself between the time before, when it "sounded fantastic"
and now, when it's running like poop......was some time passing?
You didn't do anything to the engine itself during that gap in time at all?

Yes. We changed headers and to a mini starter. That's it. It was very snappy at the throttle and idled great with a brand new Edelbrock AVS right out of the box. Then it didn't...

 

[WileERobby]

Please do my "MEF" procedure. Mechanical, Electrical, Fuel. You must do these in that order to troubleshoot.