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12-26-2020, 07:47 PM | #1 |
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Join Date: Feb 2019
Location: Estes park Colorado
Posts: 53
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Troubleshooting advice
Hello! Working on getting a 1931 Victoria back on the road. Engine was rebuilt but i dont know much about who did it etc. It does start but runs weak and sputters when you try to rev it. Spark is good, timing is good- have done it many times with nurex wrench. Known working carb was swapped over - did not fix problem. After pulling spark plugs i believe 4th cylinder is not firing- it was perfectly clean. What does everyone think the next thing to check would be? Timing gear to make sure it is indexed correctly. Or valve clearances? I have removed valve cover but have not checked anything yet. Third choice would be take the head off to investigate i guess? I only want to do this as a last resort. I have compression on all cylinders.
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12-26-2020, 07:58 PM | #2 |
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Re: Troubleshooting advice
How long has it been sitting not running? could be a bad plug to start! has happened!
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12-26-2020, 08:09 PM | #3 |
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Location: Estes park Colorado
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Re: Troubleshooting advice
Sat for a long time maybe 12years or so. Has new sparkplugs. Moved spark plugs around . #4 always perfectly clean. Has spark
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12-26-2020, 08:19 PM | #4 |
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Location: SW Virginia near the Blue ridge Parkway
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Re: Troubleshooting advice
did you do a compression test on # 4? If no compression I would pull side cover and see if valves are opening and closing.
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12-26-2020, 08:29 PM | #5 |
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Location: Estes park Colorado
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Re: Troubleshooting advice
Yes have compression on all cylinders
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12-26-2020, 08:47 PM | #6 |
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Location: Mid-Michigan
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Re: Troubleshooting advice
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12-26-2020, 08:57 PM | #7 |
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Location: Estes park Colorado
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Re: Troubleshooting advice
Its old ...i am getting spark to #4 when i gap the copper strip. I also have a cut away cap that lets you see spark going to the 4 leads in distributor looks to be working ok. I guess i could pull it and check it out. I have the puller for that.
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12-26-2020, 09:16 PM | #8 |
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Re: Troubleshooting advice
I bet your problem is an intake air leak. Do the trick with starting fluid before you start taking things apart. Goo luck.
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12-26-2020, 09:18 PM | #9 |
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Join Date: Feb 2019
Location: Estes park Colorado
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Re: Troubleshooting advice
I thought that also... no such luck. Its sealed up
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12-26-2020, 09:58 PM | #10 |
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Location: Florida Panhandle
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Re: Troubleshooting advice
Sticking valves is a high probability. Recommend dripping Marvel Mystery Oil directly into the carb intake at elevated rpm and also puting MMO in the fuel tank (4 oz. for full tank).
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12-26-2020, 11:34 PM | #11 |
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Location: Lincoln, Nebraska
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Re: Troubleshooting advice
You've said you have compression on all 4 cylinders but have you done an actual compression test? If so what are the numbers?
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12-27-2020, 09:44 AM | #12 |
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Re: Troubleshooting advice
If it sputters when you rev it might be fuel supply.
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12-27-2020, 10:08 AM | #13 |
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Location: Washington Cty., ME or Flagler Cty., FL
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Re: Troubleshooting advice
I would do the easy things first. Change the condenser. Short each plug in turn with the engine running and confirm it is the only cylinder that is missing. Change the distributer body, it could be cracked. Run the car in the garage in the dark and see if there is any, sparking where it shouldn't (distributer body, coil, down the spark plug to ground). Set points at 0.020) Good luck, Ed
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12-27-2020, 10:10 AM | #14 |
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Re: Troubleshooting advice
I second what Ed said.
It is really hard to diagnose issues over the internet. But it has to be either fuel or ignition. The plugs can be firing during idle but fail when the throttle is opened because of increased pressure. The spark has to overcome the increased pressure. If the compression numbers are good and no vacuum leaks, I would concentrate on the ignition first. Try to borrow a known good distributor and coil. The symptoms sound like a bad condenser. You can check the valve timing by bringing the engine to top dead center by using the timing pin then check to see if the valves in number 4 cylinder are off their seats by an equal amount. If they are then the cam timing is good. If not then the cam timing is bad. A fiber optic scope can be used to view the valves or a dental mirror and flash light. But do the ignition swap first.
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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. |
12-27-2020, 11:19 AM | #15 |
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Location: Grants Pass, Oregon
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Re: Troubleshooting advice
I agree with post #13 and would also dribble SEAFOAM into the carburetor when running at an increased throttle. Do this ONLY in open area as you will be getting a lot of smoke out the exhaust!
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12-27-2020, 01:16 PM | #16 | |
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Re: Troubleshooting advice
Quote:
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12-27-2020, 01:56 PM | #17 | |
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Re: Troubleshooting advice
Quote:
Have you checked for carbon arcing as suggested in post #13.
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12-27-2020, 02:29 PM | #18 |
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Re: Troubleshooting advice
Your cam is timed correctly. If not, one of the valves on cylinder 4 would have a gap where you could stick a feeler gauge. I had initially intended to peek into the spark plug hole, but your method is also correct.
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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. |
12-27-2020, 02:34 PM | #19 |
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Join Date: Feb 2019
Location: Estes park Colorado
Posts: 53
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Re: Troubleshooting advice
Yes all valves are moving... compression test had it in 50s all cylinders but it wasnt super accurate my tester not the best for large spark plug holes. Was just checking for compression. I dont think this engine was broken in much after rebuild. New coil, changed condenser, have looked at it running in the dark and did not see arcing. In tdc on the timing gear i can not get a feeler gauge in either valve on cyl 4. Is this the problem?
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12-27-2020, 02:43 PM | #20 |
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Join Date: Feb 2019
Location: Estes park Colorado
Posts: 53
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Re: Troubleshooting advice
Pulled spark plugs again.... #2 really rich, #4 perfectly clean. Dont think its firing. It is getting spark though.
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