Something BAD happened to my engine
 

And I cannot figure it out! I hope someone here will have some ideas.
First, some background. Since I got my 62 back on the road this summer, I have been chasing two (obviously related) problems: overheating (when timing is retarded) and pinging (when it is advanced) I am getting closer and this morning was quite good in both respects. I live in the middle of nowhere with 2.5 miles of dirt road in either direction. I was on my way home from the Post Office when I hit a particularly bad pothole. The entire car shook badly. I knew immediately that something was wrong as the car continued to shake badly as I tried to drive on. I wasn't sure if it was the suspension (which I had just totally rebuilt last summer) or the engine. I stopped and looked everything over and the suspension seemed OK. As I started off, it became clear that it was the engine. With any effort at acceleration, but bucked and shook badly. (Like the shift lever was gyrating wildly.) I made it home as it was mostly downhill at that point.
So here is where I'm at:
The engine starts easily and idles as smoothly as it ever has (LT-1, sort of lopey.) I can rev the engine to at least 4000 with no problems - MOST OF THE TIME. Sometimes, especially it seems if I bring the revs up slowly, it starts shaking and knocking at about 1000 and continues until I drop it back to idle. If I try to drive, it is OK on flat or down hill, but the minute there is any load on it, the engine starts bucking - maybe like it were misfiring?? When that happens, the tach jumps all over the place. Other times it is normal.Zero power. Not driveable at all. It is clearly related to the pothole incident, but I cannot imagine how.
Here is what I have done so far:

• Checked all bolts from transmission to bell housing and bell housing to engine - all good and tight.
• Checked front engine mounts - tight
• Checked all bolts on exhaust manifold - I found two a bit loose and tightened them with no change (actually the exhaust note improved, but that is all)
• Checked rest of exhaust system - all tight
• Checked all bolts on intake manifold - all tight
• Checked ignition - MSD distributor with 6A box. Box did not shake loose; all wiring OK; distributor is tight; cap, rotor, weights and springs all good; wires all good
• I pulled all the spark plugs (all looked good) and examined the pistons with a recently acquired bore scope. I was disappointed in what I could/couldn't see with the scope, but there was absolutely no carbon. The tops of the piston looked a bit pitted - similar to pictures I have seen on pre-ignition, but not bad. No oil or foreign bodies seen.
• Oil looks pristine
• Antifreeze looks good

I am really at a loss as to where to go next. There is clearly something terribly wrong here, but I haven't a clue what it is.

Somehow 'carbon track' seems to come to my mind or damaged ignition wire (although they don't usually cause a "bad" vibration). An ignition scope might help here.

Interesting, have you verified the crank damper is not coming apart or has shifted?

I agree with comment about outer ring of damper slipping especially since you have a problem setting the timing.

Please explain 'carbon track'. The ignition wires 'look' good and I'm not sure how the pothole could have damaged them. I did check that all were connected solidly. Unfortunately, I don't have access to an ignition scope.

I did, after the incident, verify TDC on the damper. I see no signs of it coming apart.

As noted above, I verified TDC and, no, I have no trouble setting timing, just finding the best timing. I can set it very stable wherever I want it. I have not, but will tomorrow, verify that the timing has not changed and is stable.

Have you looked at the distributor cap? I wonder if the impact damaged it or the rotor.

You covered several things, but you didn't mention the coil. Is it secure, have you tested it? Have you checked the float setting on the carb? Also you mention, "as son as I put a load on it" it starts bucking. I'm wondering about the physical and electrical condition. Any thoughts from anyone? :cheers: Dennis

I looked at them and they both look ok to me

The coil is solidly mounted and looks ok. How would I test it?

Verify the firing order, no crossed plug wires.

I don't see in your list that you rechecked the timing. Distributor could have jumped a bit with the jolt.

Swap a different coil in if you have one.

Vacuum leak?

Tom

That would not have changed with jolt. Car was running fine until then

I will check timing tomorrow morning. Unfortunately I do not have another coil. Could the jolt have damaged it?

Start it in a very dark place. Check for arcing. Use a spray bottle of water if necessary.

Miles on engine since rebuilding? Age of timing chain? Sudden snapping the gas pedal caused by severe jolt to car caused timing chain to jump one tooth?

You need an ohm meter. For clarification go to YouTube, search "Ignition Coil Test" (The short version).
:cheers: Dennis

i would believe the coil is a problem, but i would check the small wiring for the MSD from the dist to the coil and ign box (when i say check, i mean check the polarity of of the wiring, i have seen MSD connect things in thier harness backwards. tom

That doesn't make sense. The engine ran fine before hitting the pothole. Hitting the pothole wouldn't have caused wires to swap connections.