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Rough Idle
#1
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steve828
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Having some similar problems as Cortcomp with a rough idle on my 1954 Super Clipper L Head 327ci 165hp. I noticed when I replaced the rotor and rotor cap on the distributor that some but not all of the contacts on the old distributor cap were nicked, almost like they were neatly chipped out with a small chisel. When I put on my new cap and rotor, the distributor made a noticeable clicking noise as though the brass contact on the rotor was making physical contact with the brass distributor cap contacts. Sure enough, I removed the new distributor cap and the contacts had the same 'chiseled' appearance. Thinking that I had the wrong distributor cap, I returned the new one to NAPA and exchanged it for another one. Same thing happened again. I filed down the brass contact on the rotor a couple of millimeters and the noise went away and the car seemed to run smoothly for a while. Now it's idling roughly again and it sure seems like it's 'missing' at highway speeds. I can sometimes get it to run smoothly at idle, with just a couple odd misfires, but then the next time I run the car, back to the same rough idle and misfire issue. After reading the forums, sounds like maybe a distributor problem. Just bought the car a month ago. Was gonna start trouble shooting the carb/fuel filter, but in view of the forum info on distributors, maybe it is more effective to start with the distributor. I welcome your opinions and expertise, as always. PS, how do I get to the grease cup on the distributor to replenish it? Thank You!

Posted on: 2011/5/25 16:37
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Re: Rough Idle
#2
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Tim Cole
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Dear Steve:

The typical rotor to distributor clearance is .030 inch. So if the rotor is smashing the cap the bushings are shot.
The reason there is more clearance than spark plugs is because spark plugs operate under extreme resistance caused by compression.

I had a great test case come in today. It had a fair idle quality with steady beat on one cylinder and random misfires not sufficient inhibit driveability.

Compression was 19% lower on one cylinder and I expect it would burn a valve on a long journey at high speeds but will hold up if used for short trips.

The dwell varied depending on the tester. A cheapo meter fluctuated with random misfires and the timing was not steady around the proper setting.

However, the timing chain is loose and the carburetor castings in poor condition so condemning the distributor is a mistake because when an engine misfires the dwell changes.

This car starts hot or cold and meets the owner's needs at present, but in reality every part in the motor is shot.

I am very particular to set Packard timing using a light despite that Junior Packards have totally rotten timing marks and I attribute the satisfactory operation to proper timing. Sometimes I have to spend hours tearing a car down to accurately paint the timing marks.

Thus, I will refrain from hanging parts on a car that runs and drives okay because the results would be disappointing.

Good luck and please note that I send distributors to a leading Packard supply house and am satisfied with the results.

Posted on: 2011/5/25 17:14
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Re: Rough Idle
#3
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steve828
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Tim, I did a compression check on my 1954 L8 327CI 165HP engine this morning. Engine cold, all spark plugs removed and coil wire disconnected. Cranked the engine for two to three seconds with compression gauge attached to each empty spark plug hole. This engine has an 8:1 compression ratio and each of the 8 cylinders measured 120psi on the gauge. Looks like compression is not an issue. I will rebush the distributor and see if that brings the old girl up to snuff.

Thanks for your earlier reply.

Warren Stevens

Posted on: 2011/5/26 11:28
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Re: Rough Idle
#4
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fred kanter
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Tim,

Sound, sane, reasoned,practical and experienced advice. Now what will we all do with our clohes pins??

Posted on: 2011/5/26 11:38
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Re: Rough Idle
#5
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Bob
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Tim Would you share with us where to send a distributor for repair

Posted on: 2011/5/26 13:10
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Re: Rough Idle
#6
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Tim Cole
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Dear Packard0820:

I usually don't post names per se to avoid sensitivity issues. To do the job right a rebuilder needs one of the old time Sun Distributor machines that take up a whole service bay. Anyway my supplier has a big catalogue and an 800 telephone number.

I have a lot of faith in their sources because they were able to address concerns about Bendix Treadle Vac performance.

Another note on this case I outlined above, I failed to mention that the ignition spark was only 20KV which is below the desired 25KV. The car has a Standard Motor Parts UC14 (modern 6v) coil on it. So obviously ignition has been a problem in the past. What I found is that there is a bad connection through the ignition switch on this car that causes poor ignition.

Oh, and many thanks for the nice compliments.

Posted on: 2011/5/26 17:41
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Re: Rough Idle
#7
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Mike
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I never had the rotor to cap contact, but i'll check again when in there. Have 2 bushings anyway. Nice compression numbers!

Posted on: 2011/5/26 17:52
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Re: Rough Idle
#8
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PackardV8
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Tim Cole writes:
"I have a lot of faith in their sources because they were able to address concerns about Bendix Treadle Vac performance."

ok. What did they say or do about the BTV????

Posted on: 2011/5/26 19:19
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
http://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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