The Ford Barn

1931 flamingo · 07-19-2024, 03:49 PM

29 Ford, rebuilt engine, all four plugs firing BUT it's got a skip almost like one of the plugs isn't.
Any suggestions appreciated.

Paul in CT

nkaminar · 07-19-2024, 04:35 PM

Vacuum leak on one cylinder, low compression on one cylinder, bad plug that looks OK out of engine put is not under compression. Bad distributor housing.

Use clear plastic cap to see if there is one cylinder not consistently firing. Try all new plugs. Switch plugs around to see if miss follows plug. Search for vacuum leak using starter fluid or hose to ear. Try to find bad cylinder by shorting out one plug at a time. Take compression readings. Try new condensor. Try new wire from coil to distributor. Try new distributor housing. Clean and adjust points.

Could be carburetor. Try different carburetor.

Synchro909 · 07-19-2024, 05:51 PM

Does the "skip" occur at idle, under load or.....?
If under load, I'd look at the distributor top for the infamous #3/4 cross fire, condenser or even a bad plug.
This has the potential to go in a hundred different directions.

Gary WA · 07-19-2024, 07:30 PM

Change your plugs!!

Thodge · 07-19-2024, 07:34 PM

How fresh is the rebuild? Did the skip all of a sudden just appear or did it start doing it gradually over time? If it’s a recent rebuild, it’s less likely that it’s a valve problem but it’s worth checking. You can do a quick check by holding a piece of paper in front of the tailpipe at idle. The paper will flutter a bit normally but if you see it get sucked back against the pipe you might have an exhaust valve hanging open too long from sticking or lash adjustment.

Rob Doe · 07-19-2024, 08:08 PM

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Check the point gap. if the points close up, the points arm can short to the cam intermittently. Reset them to .020. After, check that the rub/follower block is not too worn leaving the arm too close to the cam.

1931 flamingo · 07-20-2024, 07:35 AM

New cap, points, plugs, connectors. ALL plugs fire.
The "skip" is consistent.

Paul in CT

katy · 07-20-2024, 08:44 AM

Can you isolate the "skip" to one cylinder?

nkaminar · 07-20-2024, 12:35 PM

If you tested the plugs by laying them on the head then one or more could still be bad under compression. Compressed air makes it harder for the spark to jump the gap.

Did you install a new distributor housing?

07-19-2024, 03:49 PM	#1
1931 flamingo Senior Member Join Date: May 2010 Location: new britain,ct 06052 Posts: 9,428	Mystery 29 Ford, rebuilt engine, all four plugs firing BUT it's got a skip almost like one of the plugs isn't. Any suggestions appreciated. Paul in CT

07-19-2024, 04:35 PM	#2
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 6,847	Re: Mystery Vacuum leak on one cylinder, low compression on one cylinder, bad plug that looks OK out of engine put is not under compression. Bad distributor housing. Use clear plastic cap to see if there is one cylinder not consistently firing. Try all new plugs. Switch plugs around to see if miss follows plug. Search for vacuum leak using starter fluid or hose to ear. Try to find bad cylinder by shorting out one plug at a time. Take compression readings. Try new condensor. Try new wire from coil to distributor. Try new distributor housing. Clean and adjust points. Could be carburetor. Try different carburetor. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

07-19-2024, 07:34 PM	#5
Thodge Senior Member Join Date: Apr 2024 Location: Northwest CT Posts: 225	Re: Mystery How fresh is the rebuild? Did the skip all of a sudden just appear or did it start doing it gradually over time? If it’s a recent rebuild, it’s less likely that it’s a valve problem but it’s worth checking. You can do a quick check by holding a piece of paper in front of the tailpipe at idle. The paper will flutter a bit normally but if you see it get sucked back against the pipe you might have an exhaust valve hanging open too long from sticking or lash adjustment.

07-19-2024, 08:08 PM	#6
Rob Doe Senior Member Join Date: Apr 2021 Location: Central Illinois Posts: 618	Re: Mystery Sponsored Links (Register now to hide all advertisements) Check the point gap. if the points close up, the points arm can short to the cam intermittently. Reset them to .020. After, check that the rub/follower block is not too worn leaving the arm too close to the cam. __________________ "It ain't what you know for certain that gets ya in trouble. It's what ya know for certain that just ain't so!"

07-20-2024, 07:35 AM	#7
1931 flamingo Senior Member Join Date: May 2010 Location: new britain,ct 06052 Posts: 9,428	Re: Mystery New cap, points, plugs, connectors. ALL plugs fire. The "skip" is consistent. Paul in CT

07-19-2024, 05:51 PM	#3
Synchro909 Senior Member Join Date: Jun 2014 Location: Melbourne, Australia Posts: 8,431	Re: Mystery Does the "skip" occur at idle, under load or.....? If under load, I'd look at the distributor top for the infamous #3/4 cross fire, condenser or even a bad plug. This has the potential to go in a hundred different directions. __________________ When all is said and done, more is said than done. That's why we judge people on what they do, not what they say. I sometimes wonder what happened to the people who asked me for directions. If I am not in trouble, I've done something wrong.

07-20-2024, 08:44 AM	#8
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 6,071	Re: Mystery Can you isolate the "skip" to one cylinder? __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

07-20-2024, 12:35 PM	#9
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 6,847	Re: Mystery If you tested the plugs by laying them on the head then one or more could still be bad under compression. Compressed air makes it harder for the spark to jump the gap. Did you install a new distributor housing? __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 07-20-2024 at 02:15 PM.