[C1] Something BAD happened to my engine
10-02-2023, 04:29 PM
#1
Pro
Thread Starter
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:
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
Last edited by dmtparker; 10-02-2023 at 04:32 PM. Reason: Added info
Popular Reply
10-11-2023, 03:07 PM
Pro
Thread Starter
Solved!
And you will NEVER guess how. Yesterday, I got home with my borrowed Blaster 2 coil and 6AL box. First I swapped out the coil (easier to do) - no improvement. Then I swapped out my 6A for the 6AL - Started fine and ran OK until I started up hill. Then it bucked and misfired and then died. Completely. Would not start. I had to use the starter to back the car around and into the carport. Putting a timing light on the coil to distributor wire, I confirmed 0 spark. A this point I swapped my original parts back in. Same result. So I started testing. My entire ignition system is MSD - billet distributor, coil, 6A box. Using a link provided a couple pages back (Thank-you!) I went to the Holly (MSD) website and reviewed their trouble shooting. I do not have a helper so jumping the magnetic sensor wire to test for spark was not possible. Instead, I took the unused white wire (used with points) and scratched it on a good ground while holding a spark plug (plugged into the coil directly) against ground. No spark. Remember, the engine was running a few minutes ago. Well, is there 12 v to the red wire on the 6A? No. Why not? The red wire is plugged into a junction on a plastic extender on the + coil post. That extender connects the 6A red to the original 'hot' wire to the coil which comes off the ballast resistor. (in this application, the ballast resistor is not used, but functions solely as a connection point for several wires.) Sure enough, the brown wire from the ignition switch was sitting there - pulled out of its ring connector. I replaced the connector (with a heat shrink one this time!) and the car runs great.
The best I can figure is that when I hit the pothole, the engine and the body got racked in opposite directions, pulling the brown wire partly out of the ring connector. When it was making contact, all was well. Whenever the engine torqued slightly (like giving it gas up a hill), the connection became tenuous and the engine misfired. This went on until the wire pulled out completely and I could find it.
Thanks to everyone for your help! Especially to 68sixspeed for loaning the coil and box - I'll get it back in the mail to you soon. This forum is the best!
The best I can figure is that when I hit the pothole, the engine and the body got racked in opposite directions, pulling the brown wire partly out of the ring connector. When it was making contact, all was well. Whenever the engine torqued slightly (like giving it gas up a hill), the connection became tenuous and the engine misfired. This went on until the wire pulled out completely and I could find it.
Thanks to everyone for your help! Especially to 68sixspeed for loaning the coil and box - I'll get it back in the mail to you soon. This forum is the best!
10-02-2023, 05:16 PM
#2
Drifting
Pro Mechanic
Member Since: Jun 2017
Location: Central Michigan
Posts: 1,739
Received 1,322 Likes
on
494 Posts
2023 C1 of the Year Finalist - Modified
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.
10-02-2023, 05:36 PM
#4
I agree with comment about outer ring of damper slipping especially since you have a problem setting the timing.
10-02-2023, 06:08 PM
#5
Pro
Thread Starter
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.
10-02-2023, 06:09 PM
#6
Pro
Thread Starter
10-02-2023, 06:10 PM
#7
Pro
Thread Starter
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.
10-02-2023, 06:34 PM
#9
Race Director
Member Since: Jan 2002
Location: Close to DC
Posts: 14,568
Received 2,142 Likes
on
1,476 Posts
C2 of the Year Finalist - Modified 2020
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? 
Dennis
Dennis
10-02-2023, 06:59 PM
#10
Pro
Thread Starter
10-02-2023, 07:00 PM
#11
Pro
Thread Starter
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? Dennis
Dennis
10-02-2023, 07:39 PM
#13
Drifting
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
Swap a different coil in if you have one.
Vacuum leak?
Tom
10-02-2023, 07:45 PM
#15
Pro
Thread Starter
I will check timing tomorrow morning. Unfortunately I do not have another coil. Could the jolt have damaged it?
10-02-2023, 08:13 PM
#18
Race Director
Member Since: Jan 2002
Location: Close to DC
Posts: 14,568
Received 2,142 Likes
on
1,476 Posts
C2 of the Year Finalist - Modified 2020
10-02-2023, 08:16 PM
#19
Advanced
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
10-02-2023, 08:27 PM
#20
Race Director
Member Since: Feb 2007
Location: northern california
Posts: 13,660
Received 6,590 Likes
on
3,029 Posts
C2 of Year Finalist (track prepared) 2019
The following 2 users liked this post by jim lockwood:
Dan Hampton (10-06-2023),
Westlotorn (10-03-2023)