12 Volt Cap

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RacinJason
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12 Volt Cap

Post by RacinJason » Fri Jun 01, 2018 10:04 am

WHY is the 12 Volt Cap (on my 420) different from the 6 Volt Cap> As I've been running on a 12v battery, I decided to install a 12v cap. Rotated the distributer 90 degrees, and the engine fired right up...on Number 2 Cylinder! This Dozer has run faithfully for the last 4 or 5 (?) years on 6 v system with a 12 volt battery. Last month, I guess it got tired of that arrangement, and petered out and died, while I was warming it up for an oil change. Changed plus, wires, points, condenser and 12 v cap. Put 6 volt cap back on, put the timing light on either cylinder, got spark. Engine ran great, but didn't drive it. Next day, it started, then petered and died. Cyl. 1 has 85# , #2 has 125#. Also, major blowby, prob from #1 cyl. Mainly curious, about the towere on 12 v cap being 90 degrees from the 6v cap. ???
JD 112, JD 420 C

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Stan Disbrow
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Re: 12 Volt Cap

Post by Stan Disbrow » Fri Jun 01, 2018 3:45 pm

Hi,

12 volt cap? The caps have nothing to do with the battery voltage. So, I have no idea what you have going on. Sounds like you have the wrong cap, period. The compression is a whole other can of worms.

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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RacinJason
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Re: 12 Volt Cap

Post by RacinJason » Fri Jun 01, 2018 5:37 pm

I wrote another (long) paragraph and just about finished, when the computer started going nuts. Unresponsive, then adding unrelated pages, blocking JDcrawlers, then finally clearing out my reply. I wonder if anyone has had this problem? I am going to post this message to see if it goes thru, then will try to add some sense to my original post, sometime later. Sorry, RacinJason Even now, my typing is being dropped, and I have to repeat.
JD 112, JD 420 C

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RacinJason
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Re: 12 Volt Cap

Post by RacinJason » Fri Jun 01, 2018 7:41 pm

Gonna try again, short and sweet! Why are the towers on a 12 volt distributor cap 90 degrees counterclockwise from those on a 6 volt cap? Also, when changing to a 12 volt cap, do you need to turn the distributor shaft (rotor) 90 degrees, or just the housing?
JD 112, JD 420 C

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Lavoy
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Re: 12 Volt Cap

Post by Lavoy » Fri Jun 01, 2018 8:26 pm

It has nothing to do with voltage, you have the wrong cap, it will not work. Buy the correct cap.
There is no such thing as a 12 volt cap, the cap you are referring to just happens to be from an application that is a 12 volt system. The fact that it will clip on your distributor means nothing.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
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Stan Disbrow
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Re: 12 Volt Cap

Post by Stan Disbrow » Sat Jun 02, 2018 4:21 am

Hi,

Ah. I see now. What you have is a cap from another model distributor. They made hundreds of distributor models, many of which the matching caps cross fit. And, what you see as a 12v unit just happened to be used on a machine with a 12v system. It is the coil which is 6v or 12v, of course.

There were other 2-cyl engines other than Deere out there back in the day, so there are other distributors and caps which went with. Some of those have different timing and so their high voltage connections are not in the same place relative to the keying as the Deere ones.

I have seen where folks have used 4-cyl caps on Deere 2-cyl engines and used the matching pair or towers, leaving the other two unconnected of course. In your case your two towers are simply in the wrong place for your engine.

Oh, and on the Deere engine you can't rotate the distributor shaft. It is keyed to the oil pump which drives it. And, the oil pump is set to the camshaft which drives it using a special timing tool when installing the oil pump. All you can do is rotate the housing and then make new longer wires as the original length ones will be too short. What I think happened to you there is you got the wires to fit but are now out of time and only one cylinder is firing.

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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gregjo1948
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Re: 12 Volt Cap

Post by gregjo1948 » Sat Jun 02, 2018 5:05 am

Your compression shouldn't be so greatly different. Sounds like you might have a valve or ring problem on one cylinder.
JD 350B diesel w/rops & 6way blade, Case 580B Loader/backhoe, Farmall 504 highcrop, International 404 utility, International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller

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RacinJason
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Re: 12 Volt Cap

Post by RacinJason » Sat Jun 02, 2018 2:00 pm

Some good info from you gurus! I had bought the 12 v cap a while back, as it seemed the thing to do. I had seen a 440 with a similar cap. At least t's easier to unhook the rear clip. LOL OK, I did put the original cap back on, and the engine ran well for a few minutes, till I shut it off. It was firing on both cylinders, as I put the timing light on it. As I said, the next day it started, but just seemed to die. I noticed the spark seemed erratic, and I found the distributor had a bit of play, which made it difficult to adjust the points. (I ordered a new bushing) I think it may be a combination of problems, which include the low compression in #1 cylinder. It actually ran better on one cylinder, with the "12 v cap", so I think the blowby from #1 is preventing #2 from getting a good charge of fuel. Will be getting back to ME in a few days and will pull the wire from #1 to see if it runs better, while moveing the dozer to a good spot for changing engines. Have a good (hopefully) running one coming, so will play around with this one. Also, I am bringing my dwell meter, to check on the distributor situation. I asked the guys at Advance Auto Parts if they had a dwell meter, and they said,"What's that?" I be dozin' soon, Jason
JD 112, JD 420 C

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