Dan Hampton

The MSD box didn't shake loose but how do you know that the internals are OK? My guess is ignition. Do you have a point/condenser distributor you can transplant to see if the MSD system is, in fact, the culprit? That would seem like a quick way to prove or disprove the ignition as the problem.

paw

the problem was there before the pothole

dmtparker

No. There was no problem before the pothole. I was fooling around with the timing - varying from 8*BTDC to 14* trying to balance overheating and pinging, but the car was running fine.

MelWff

why aren't you setting it for the stock 1962 timing for whatever engine you have?

dmtparker

I wish I did, but, no, I don't have another distributor. I will double check all the wiring and maybe even open up the box to see if I can see anything. It sure sounds like ignition to me too.

dmtparker

The engine is one I built many years ago and is essentially a '70 LT-1 which calls for 14* BTDC, however, there were a variety of different timings called out for the LT-1. My daughter had custody of the 62 for several years and her friend (a good mechanic) had set the timing to 8* (why I don't know) which gave a total of only 32* and was overheating. I have been dancing between 8 and 14 trying to get the heat down and the ping under control.

dmtparker

Will check that out. Thanks

dmtparker

Wow! I really appreciate all the thoughts and suggestions. It is clear that tomorrow I need to pull out the timing light and verify both that the timing is unchanged and that it is stable. Maybe I can get the engine to do its whacko thing and see what the timing does. I'll check out the coil as suggested. I'm not sure what I'm looking for, but I'll open up the 6A box and have a look. Given that at times it can rev up to 4000 rpm with no problems and other times it is terrible just off idle, it sure sounds like an ignition problem rather than something mechanical.
Keep the ideas coming and I'll let you know what I find tomorrow.

MelWff

I have a 70 LT1 in my 69. The distributor springs are from a Mr Gasket 928G kit. I also have the bronze advance stop bushing installed. My initial timing is 12 for a total mechanical of 36. The modified vacuum advance adds another 10. Do you have the stock advance springs? Are you using 93 octane gasoline?

dmtparker

Not really germane to the present problem, but I have the stiffest springs of the Mr Gasket set installed which gives me 24* @2300 rpm. Static is 12*. The vac adv is a B26 and just yesterday I put in a stop to limit it to 10*. I run 93 unleaded and just started adding a half bottle of Octane boost per tank. That was the best combo so far until disaster struck.

TCracingCA

I am more leaning toward your crankshaft snapping.

Are you sure there was a pothole?

68sixspeed

I have a MSD coil and older 6AL box I can loan you if you want to rule that out.

I've actually had really good luck with the small cap HEI type ignition on a couple cars now and the cost isn't bad. (not opening the points vs msd vs hei thing here, I have all 3 and they all work when properly serviced). https://www.ebay.com/itm/32304666650...Bk9SR6Drn9veYg

-Dan

BADBIRDCAGE

Check every electrical connection in the engine compartment. A hard jolt as you describe could dislodge a ground or a connector. Maybe not completely but enough to disrupt the circuit.

dmtparker

Yes to the pothole. How could I rev the engine up to 4000 nice as can be with a snapped crank? Is that even possible?

Tiros

First thing that came to my mind, Did you do this?

Hmm...loose hold down bolt from recent work?

dmtparker

Well, I have more info. This morning I rechecked the timing - exactly as before - 14* static, 38* total and very stable - even when engine was knocking, bucking whatever you call it. Next I checked the coil (MSD Blaster, vintage 1995) 1* measures 0.7 which is within spec according to Holley. 2* is 11k to either 1* stud which again is within specs. No short to ground. Reattached all wires and made sure they were tight. Started engine. It started with really bad shaking and bucking then died and would not restart. Using timing light, I confirmed no spark from coil. Yes, I checked and re-checked all the connections.
So the problem IS ignition - unless you want to suppose more than one problem. I have no idea how to differentiate coil from 6A box. I pulled out the box (what a PITA - I taped everything up nice and neat when I installed it nearly 30 years ago. Old electrical tape sucks!). The box is totally sealed with no way short if cutting it open to look at the insides. Fortunately, and VERY kindly, 68sixspeed has offered to loan me a spare coil and box that he has. I will pick it up this weekend and see what I can find out then.

Tiros

Just one more thing to consider is the input trigger to the MSD. What kind of distributor are you using, and can you confirm the the MSD is seeing a trigger from your distrib?

thoyer

Since it got worse after messing with the coil wires you may have narrowed your search. Do you have another coil wire to try?

dmtparker

I have a MSD distributor. It uses a magnetic 'paddle wheel' and sensor. It all appears to be OK, but not sure how to test it.

TCracingCA

Ya, believe it or not, as the rods are holding it together, the bearing journals.

As you say when you slow it all back down, then you are getting the vibration.

In the Porsche world, this happens. But glad there was a pothole, and I seriously hope it is something just jolted and I see your morning troubleshooting has you focused on ignition, etc.