no park at #4 piston

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Vinny b
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no park at #4 piston

Post by Vinny b » Sat May 23, 2020 3:00 pm

when i short out the plugs at the terminal that passes thru the firewall from the coilbox at get spark at 1,2 & 3. nothing at #4. i have switched around the coils which are new from langs and get the same result. what's next ? timer ?
1913 T touring
1931 A roadster


Jerry VanOoteghem
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Re: no park at #4 piston

Post by Jerry VanOoteghem » Sat May 23, 2020 3:15 pm

Even though you're getting no spark, is the coil still buzzing? If the coil is buzzing, but you get no spark at the coilbox spark plug wire terminal, then the timer and wiring are okay. The problem is then an internal short within the coilbox itself.

If you get no coil buzzing on #4, then check the timer and the wires from the timer to the coilbox. Also check the contacts within the coilbox in the #4 coil position. Make sure the contacts are not flattened out such that they're not touching the coil contact buttons.

Let us know what you find.


Scott_Conger
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Re: no park at #4 piston

Post by Scott_Conger » Sat May 23, 2020 4:37 pm

And, if it IS buzzing, but no spark, do not let the coil buzz but for a second. A coil that is unable to find ground will short out very very quickly.

Buzzing, with no spark would be a very unusual situation since there is so little to go wrong with that connection in the coil box. I'd more suspect that there is NO buzzing going on, and Jerry has given good advice.

I only wanted to jump in to warn to not let ANY coil "buzz" if it's output was not going to a sparkplug (ground). Don't want to injure those nice new coils.
Scott Conger

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Norman Kling
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Re: no park at #4 piston

Post by Norman Kling » Sat May 23, 2020 4:45 pm

Three things about the coil box. 1. The contact springs should make a solid connection with the coil. 2. If the engine was run without a good spark plug or good wire between the coil box and the spark plug, your spark can still go to ground through a carbon trace on the wood of the coil box. This would be especially true if the wood should get wet from either rain getting to it or from washing the car. Once the spark crosses the wood and grounds out, it burns a carbon streak in the wood and the spark will continue to go to ground before it reaches the spark plug. 3. The lid must be on the coil box to push the coils down to make a good connection at the bottom.

You can buy a plastic replacement from the vendors for the wood on the coil box. It looks like wood and will keep you from having the carbon form on the box.
Norm


John kuehn
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Re: no park at #4 piston

Post by John kuehn » Sat May 23, 2020 8:01 pm

Is it a original coil box? Over time the screws on a coil box either get lightly corroded or rusty. The originals had a copper coating of some sort and those old screws and nuts loose their continuity after many years.
My 1919 Roadster had occasional rough running issues and after rebuilding the coil box it made a big difference. If you rebuild it be sure to use the original contacts as they are much better than a lot of the reproduction ones. The contact bolts are another story. Adding rebuilt coils later later didn’t hurt a bit either in my case.
Same goes for the original battery cables and original wiring. Old wiring eventually does need replacing. It made a difference in my case and a lot starting with a rebuilt coil box.


DickC
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Re: no park at #4 piston

Post by DickC » Sun May 24, 2020 3:48 am

I would eliminate the spark plug as the problem first. Try moving the plug to another location to see if there is spark. If no spark, then go to other possible causes. Just my simple mind working too hard. Dick C.

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