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Old 08-04-2019, 07:40 AM   #1
Bob from Northport
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Default Distributor question

We have a high point 1930 Roadster in the shop. Getting difficult to start.
The distributor cam/rotor can be moved back and forth about 1/2" which I think is far too much play. We have checked the timing with a light and it is fine.
Is there excessive wear on the distributor gear?? Or the cam shaft gear that could be causing the timing to change?? With a timing light I can see the timing mark moving back and forth slightly when retarded. Or wear on the timing gears???

Thanks!!
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Old 08-04-2019, 08:36 AM   #2
alexiskai
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Default Re: Distributor question

I think in previous threads on similar topics, the consensus has been that you just gotta open the valve cover and see what's going on in there.
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Old 08-04-2019, 08:55 AM   #3
Joe K
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Default Re: Distributor question

The distributor gear issue shouldn't be causing difficulty to start - free motion is all in one direction and your timing is your timing based on take-up of that free motion.

Now friction between the distributor cam and your breaker points MAY cause irregularity in the timing - which MIGHT affect firing. Normal recommendation is a drop of oil here.

While you're at it check your points condition. I use a piece of garnet sand-paper folded back on itself to present two opposite side of grit. This is pinched between the moving point and the stationary contact and "pulled" out to sandpaper the two contacts to uniform contact.

My Model A Mentor says if you can burnish the points by this method down to 80 percent contact surface, you have it about as perfect as it can be.

Don't use emery (black) sandpaper as the dust is conductive.

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Old 08-04-2019, 09:06 AM   #4
redmodelt
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Default Re: Distributor question

I just went thru a distributor that had the same issue. The tang on the shaft was about half gone. Had to replace the intermediate shaft, the slot that mated with that tang was crushed to take up some of the slop. That is a far as I went with it. Any slop in the drive gear will be taken out by rotation when I set the points and timing.
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Old 08-04-2019, 09:10 AM   #5
Bob Bidonde
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Default Re: Distributor question

Things to check:
> Condition of teeth on the distributor - oil pump drive gear assembly;
> Play in shafts connecting the distributor to the drive gear assembly;
> Resistance from the fixed point in the distributor to the battery's ground post. Resistance greater than 2 or 3 Ohms may result in hard starting and poor ignition performance. High resistance is typically caused by too many painted surfaces and a haphazard ground path to the engine. Add a jumper cable to the transmission cover from the battery ground on the crossmember.
Attached Images
File Type: jpg Ground Resistance Check.jpg (17.1 KB, 34 views)
File Type: jpg Battery Ground Connection Exploded View(3).jpg (48.7 KB, 30 views)
File Type: jpg Camshaft & Distributor Drive Gear.jpg (11.4 KB, 31 views)
File Type: jpg Engine Valve Chamber (1).jpg (72.7 KB, 49 views)
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Old 08-04-2019, 09:16 AM   #6
Bob Bidonde
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Default Re: Distributor question

Things to check:
> Condition of teeth on the distributor - oil pump drive gear assembly;
> Play in shafts connecting the distributor to the drive gear assembly;
> Resistance from the fixed point in the distributor to the battery's ground post. Resistance greater than 2 or 3 Ohms may result in hard starting and poor ignition performance. High resistance is typically caused by too many painted surfaces and a haphazard ground path to the engine. Add a jumper cable to the transmission cover from the battery ground on the crossmember.
Attached Images
File Type: jpg Ground Resistance Check.jpg (17.1 KB, 5 views)
File Type: jpg Battery Ground Connection Exploded View(3).jpg (48.7 KB, 2 views)
File Type: jpg Camshaft & Distributor Drive Gear.jpg (11.4 KB, 2 views)
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Old 08-05-2019, 07:10 AM   #7
Dan/Kzo
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Default Re: Distributor question

If a wireless lower plate was used, such a hard starting condition an occur when the tab rubbing against the bottom plate developed an electrical wear path.
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Old 08-05-2019, 02:40 PM   #8
Chuck Sea/Tac
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Default Re: Distributor question

Quote:
Originally Posted by Dan/Kzo View Post
If a wireless lower plate was used, such a hard starting condition an occur when the tab rubbing against the bottom plate developed an electrical wear path.
I just helped a club member out with this same problem. Not only was the tab not matching the contour of the spring loaded plate, but the tab was at an angle so only one little corner was rubbing right on the edge.
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Old 08-06-2019, 09:27 AM   #9
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Default Re: Distributor question

Quote:
Originally Posted by Dan/Kzo View Post
If a wireless lower plate was used, such a hard starting condition an occur when the tab rubbing against the bottom plate developed an electrical wear path.
X2. Had this issue with modern wireless plates, all kinds of odd issues, hard start, hesitation/slight miss at lower revs/hard pulls (up hills), etc. Converted back to original plates - issues resolved.
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