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08-13-2019, 02:09 PM | #1 |
Member
Join Date: May 2010
Posts: 37
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model a engine jumps time
checked distributor drive gear....ok camshaft next?
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08-13-2019, 02:21 PM | #2 |
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Join Date: Apr 2015
Location: Boise, Idaho
Posts: 1,580
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Re: model a engine jumps time
Make sure you have the washers under the cam screw....the cam may be moving on the shaft...
https://www.brattons.com/distributor...with-hole.html .
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Early '29 CCPU that had a 4-speed, but not any more.......in the family since '62 |
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08-13-2019, 02:44 PM | #3 |
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Join Date: May 2010
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Re: model a engine jumps time
Please note that SOME repro screws are too long and the effect is same same missing a washer if used with original thin lock washer and original thin flat washer!
The screw bottoms out before the cam is tight. The long REPRO screws come with an extra thick lock washer to correct this. So if you use the long repro screw with original THIN lock washer and original thin flat washer the cam will slip. Last edited by Benson; 08-13-2019 at 02:53 PM. |
08-13-2019, 03:13 PM | #4 |
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Join Date: Apr 2015
Location: Boise, Idaho
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Re: model a engine jumps time
Another thought...the cam itself has teeth on the bottom...perhaps yours is worn?
https://www.brattons.com/distributor-cam.html .
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Early '29 CCPU that had a 4-speed, but not any more.......in the family since '62 |
08-13-2019, 03:36 PM | #5 |
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Location: Oregon
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Re: model a engine jumps time
I had a Model A that jumped time every time I hit a bump or hit the brakes. I would then have to pull over and reset the timing again. I went over the distributor several times, switched to another distributor known to be good, but the problem persisted.
I later found that the spring inside the camshaft thrust plunger had broken due to rust. This allowed the camshaft to move back and forth resulting in variable ignition timing. When the timing was reset, the act of pulling back to take up slack on the distributor shaft moved the camshaft (and its drive gear) back to the correct position. After resetting the timing, the engine ran fine until I hit a bump, sneezed, scratched my bum, or had impure thoughts. Check that out as a possible cause. |
08-13-2019, 05:32 PM | #6 |
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Location: Melbourne, Australia
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Re: model a engine jumps time
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08-15-2019, 06:07 AM | #7 |
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Re: model a engine jumps time
or had impure thoughts
unconfessed sin will get you every time! lol |
08-16-2019, 11:09 AM | #8 |
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Join Date: Jun 2010
Location: Temecula, CA
Posts: 4,110
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Re: model a engine jumps time
I understand having impure thoughts, but it is unsafe to scratch your bum while driving!!! This from the CA DMV booklet. -
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08-16-2019, 04:18 PM | #9 |
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Join Date: May 2010
Location: now Kuna, Idaho
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Re: model a engine jumps time
And, DO NOT FORGET: "This action is known to the state of California to cause cancer, reproductive harm, warts and ingrown toenails." So stay out of California, and you'll be safe!
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