Running issues...

[ChrisWood]

Hi – I hope I can be guided in the right direction. I’m having a running issue with 6037 and can’t seem to track it down. It starts fine cold and warm. Idles fairly smooth but slight miss. Runs strong under load but when it levels out around 40-60 MPH it seem to buck and jerk. It did start making a intermittent whine which I though was a belt but could be a vacuum leak. Doesn’t do it on idle but if I rev it up it will come and go. I went ahead and changed plugs and wires and no change. Any advice on next steps?

Thanks in advance for any advice…

[Ron]

If you pull the plug wires one at a time and listen for one that does not change the sound of the engine, it may point you to the problem cylinder....

Otherwise, try to post a video.

[Michael]

Do you know when the last time the cap and rotor have been replaced?

[Bitsyncmaster]

I went through a lot of parts replacement trying to find my skip problem. I would suggest you first try a bottle of injector cleaner in a tank of gas since this is a cheap fast thing to try.

[ChrisWood]

Thanks for the feedback. I have not replaced the cap and rotor yet and I will try the cleaner asap. I did upload the video of it running.... Let me know what your thoughts on the sound.

Thanks again

https://www.youtube.com/channel/UC4vwWfQHghJKu4nfmCXY3Lw

[Michael]

If it were mine, I would first want to see what the mixture is doing. If you knew it was set correct and now the dwell is off, might lead you to a broke vacuum line that holds at idle, leaks at throttle or something along those lines. Don't discount a bad distributor cap though. When they crack or get worn, you can chase your tail looking for random issues.

Also sounds like you have a pretty nasty valve slapping or an exhaust leak.

[David T]

Verify proper base timing, vacuum and mechanical advance. If you are not getting all of the advance in, it can cause this at higher RPM's. You can also be having break-down of the secondary ignition system. You might need to replace the spark plugs, ignition wires, cap, rotor, and coil. Basically you need to do a tune-up and maybe clean the fuel injectors. Do you have fresh gas in the tank? You could try a can of Techron and see if that helps.

[Michael]

Verify proper base timing, vacuum and mechanical advance. If you are not getting all of the advance in, it can cause this at higher RPM's. You can also be having break-down of the secondary ignition system. You might need to replace the spark plugs, ignition wires, cap, rotor, and coil. Basically you need to do a tune-up and maybe clean the fuel injectors. Do you have fresh gas in the tank? You could try a can of Techron and see if that helps.

And for the OP, in case you didn't read any of the other replies, here we have David T to sum it all up in one concise report that he made all by himself with no help from anyone else.

[Jonathan]

Is your tamper proof cap still in place covering the mixture adjustment screw? Hopefully that’s the case so you can assume the mixture setting is still ok. If that cap isn’t in place still, it looks like you are missing something to plug it.

[Michael]

Is your tamper proof cap still in place covering the mixture adjustment screw? Hopefully that’s the case so you can assume the mixture setting is still ok. If that cap isn’t in place still, it looks like you are missing something to plug it.

Nice catch.

[Jonty]

Sounds like is it sucking in air from somewhere it shouldn’t. I agree with the poster that said make sure you have the mixture screw bung in. It can sound like that if you take the bung out

[Ron]

Thanks for the feedback. I have not replaced the cap and rotor yet and I will try the cleaner asap. I did upload the video of it running.... Let me know what your thoughts on the sound.

Thanks again

https://www.youtube.com/channel/UC4vwWfQHghJKu4nfmCXY3LwIt sounds like it is missing a full lick to me, i.e. not just a random misfires. One cylinder is unhappy...
I'll suggest again :) that you pull the plug wires one at a time and listen for no change.
...From the vid, I would try it at a steady RPM of ~1400.

FWIW, I noticed at 0:19 seconds that #6 plug wire jumped, so I'd try it first.
Maybe the spark plug is loose....maybe nothing to it??

If no luck, compare plugs..