Just finishing my inner fender replacement and started the engine for the first time in nearly a month. While apart I replaced the sparkplugs (was 43xls now 44xls as book calls out), points, cap, rotor. Did not replace wires as they are fairly new. Unknowingly had ignition in on position (probably 1-2 hours) when installed new battery (before replacing points). Engine ran fine before I started project, now mis-fires under load, and gets worse as engine heats up. Any ideas?
John D said
Jun 29, 2012
Could have possibly burnt the point contacts.
69chvldrvr said
Jun 29, 2012
Replaced points after ignition mishap.
Lost in the 60s said
Jun 29, 2012
69chvldrvr wrote:
Replaced points after ignition mishap.
Is it possible you got a couple plug wires mixed up ?? 5 and 7 are very easy to do that with.
SShink said
Jun 29, 2012
May be a dumb question... but did you reconnect the vacuum advance hose after replacing the cap?
69chvldrvr said
Jun 29, 2012
I did indeed. Good question though.
dashboard said
Jun 29, 2012
cap? dwell?
yellowbowtie said
Jun 29, 2012
I agree with Mitch. Only because I have done this before. Engine will idle fine but stumble under load
Chris R said
Jun 29, 2012
If you dont have a crossover in your exhaust system, you can have a partner rev the engine up in drive with foot on the brake, while you stand behind the car and see which tail pipe the missfire is coming from. You then narrow which bank of cylinders the missfire is on. Works even better for those that know its really one cylinder thats missfiring.
SShink said
Jun 29, 2012
Lost in the 60s wrote:
If the wires are on correctly, I would suspect a bad plug. If you can locate which side with Chris' suggestion, pull those back out and see if they are all firing. It will be obvious if one isn't.
I woke up thinking the same thing with the bad plug. The other thing you can do if you have a temp gun is let the car idle for a bit, then check the exhaust manifold temps just where it comes out of the cylinder. The one(s) that are cooler aren't firing completely (or at all...). Then you can swap the wires and/or plugs with a known good cylinder to trouble shoot it.
-- Edited by SShink on Friday 29th of June 2012 07:42:16 AM
69chvldrvr said
Jun 29, 2012
Thanks to everyone for their suggestions. Will be busy tonight. The sad part is the engine ran fine before I started the project. But as long as the inner fenders were out, and everything was easily accessible, seemed like a good time to clean up the engine compartment and replace parts...One thing led to another...I guess "if it ain't broke, don't fix it".
-- Edited by 69chvldrvr on Friday 29th of June 2012 09:32:29 AM
Lost in the 60s said
Jun 29, 2012
If the wires are on correctly, I would suspect a bad plug. If you can locate which side with Chris' suggestion, pull those back out and see if they are all firing. It will be obvious if one isn't.
Tim H said
Jun 29, 2012
If your wires are installed correctly then check the inside of the new cap to see if it is tracking or if there is and grease, finger prints ect that could cause tracking. Try putting the old cap back on and see what happens.
SShink said
Jun 29, 2012
Jeff, I'm sure you'll figure it out. We all go through this phase with these cars depending on how much we let it snowball. Sometimes the simplest change can cause the most headaches...
Step back, take a fresh look at things, and sometimes the obvious will jump out at you. Or, have someone else look at it with you and they will see what you are missing.
These cars are relatively simple mechanical things, and you will learn from the experience, as we will as well since you are sharing the frustrations and asking for input.
69chvldrvr said
Jun 29, 2012
Found the culprit....Removed all the plugs one-by-one and checked for cracks, and rechecked the gap. None showed any signs of damage, and the gap was spot-on, except for one. It had no gap whatsoever. Don't know what happened to that one. Gapped it to the correct .035, put it back in...RUNS GREAT!......Thanks to all who gave suggestions!
SShink said
Jun 30, 2012
That's great Jeff! Sometimes it's the simple stuff.
Are you going to park with us at Car Craft?
Tim H said
Jun 30, 2012
Jeff
How did the wheel wells fit? They seemed to be nice quality ones.
Just finishing my inner fender replacement and started the engine for the first time in nearly a month. While apart I replaced the sparkplugs (was 43xls now 44xls as book calls out), points, cap, rotor. Did not replace wires as they are fairly new. Unknowingly had ignition in on position (probably 1-2 hours) when installed new battery (before replacing points). Engine ran fine before I started project, now mis-fires under load, and gets worse as engine heats up. Any ideas?
Replaced points after ignition mishap.
May be a dumb question... but did you reconnect the vacuum advance hose after replacing the cap?
I did indeed. Good question though.
If you dont have a crossover in your exhaust system, you can have a partner rev the engine up in drive with foot on the brake, while you stand behind the car and see which tail pipe the missfire is coming from. You then narrow which bank of cylinders the missfire is on. Works even better for those that know its really one cylinder thats missfiring.
I woke up thinking the same thing with the bad plug. The other thing you can do if you have a temp gun is let the car idle for a bit, then check the exhaust manifold temps just where it comes out of the cylinder. The one(s) that are cooler aren't firing completely (or at all...). Then you can swap the wires and/or plugs with a known good cylinder to trouble shoot it.
-- Edited by SShink on Friday 29th of June 2012 07:42:16 AM
Thanks to everyone for their suggestions. Will be busy tonight. The sad part is the engine ran fine before I started the project. But as long as the inner fenders were out, and everything was easily accessible, seemed like a good time to clean up the engine compartment and replace parts...One thing led to another...I guess "if it ain't broke, don't fix it".
-- Edited by 69chvldrvr on Friday 29th of June 2012 09:32:29 AM
If the wires are on correctly, I would suspect a bad plug. If you can locate which side with Chris' suggestion, pull those back out and see if they are all firing. It will be obvious if one isn't.
Jeff, I'm sure you'll figure it out. We all go through this phase with these cars depending on how much we let it snowball. Sometimes the simplest change can cause the most headaches...
Step back, take a fresh look at things, and sometimes the obvious will jump out at you. Or, have someone else look at it with you and they will see what you are missing.
These cars are relatively simple mechanical things, and you will learn from the experience, as we will as well since you are sharing the frustrations and asking for input.
Found the culprit....Removed all the plugs one-by-one and checked for cracks, and rechecked the gap. None showed any signs of damage, and the gap was spot-on, except for one. It had no gap whatsoever. Don't know what happened to that one. Gapped it to the correct .035, put it back in...RUNS GREAT!......Thanks to all who gave suggestions!
That's great Jeff! Sometimes it's the simple stuff.
Are you going to park with us at Car Craft?
How did the wheel wells fit? They seemed to be nice quality ones.