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Standard Twin Proper Spark Plugs?


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#1 mrf1002u OFFLINE  

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Posted November 30, 2012 - 10:39 AM

Anybody know what the original equipment spark plugs were in a Standard Twin Tractor when they were new? Posted Image I have the manual and it doesn't say. A search in the forums found nothing either.
Mine has some really old Champion UD-16 plugs in it, but I do not know if these are right for the engine. I can cross them to current replacements, but I want to make sure I am crossing FROM the right number to start with. These were made when Champions were still good plugs, but I want to make sure I am using a plug with the right specs.

#2 mrf1002u OFFLINE  

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Posted November 30, 2012 - 10:41 AM

Is it a Champion model X? I did find that somewhere after a lot of reading. I don't really want the X's if that is correct. Too expensive. Just want to cross to the right number in Autolite or whatever.

#3 DougT ONLINE  

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Posted December 02, 2012 - 10:04 AM

A Champion X is 1/2" pipe thread. I don't think the twin used that. I wouldn't beat mysef up too bad over the original numbers. Obviously the ones in there now worked for your dad and hasn't hurt the engine. An old spark plug catalog would probably have a listing for the twin.
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#4 mrf1002u OFFLINE  

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Posted December 02, 2012 - 08:33 PM

Hadn't thought of the catalog route, I may look for that. This tractor is hard to start, so it was more about making sure the plugs are the right specs to make sure it is no harder to start than necessary. I know reach and heat range can have an effect on starting and running.

Actually I have pretty much made up my mind that the mag needs to be rebuilt. It has spark but not that great. You can hold the wires and you don't get that feeling like your fingernails are gonna fall out, or that arm jerk thing. If you have ever held a good hot mag lead, then you know what I mean. Not sure how "hot this Wico A 32b should be, but it seems a little weak.

I was up in the air about it being a fuel issue or a spark issue. Since then, I have tried a different carb (Flojet) and I seem to have the same problems, so I think the mag will have to be my next step. I may try points and condensor in the mag before I take that step, just to see if it helps, but I really think there may be an issue in the impulse. The engine will try to start over an over but shuts down after it fires about 3 times. I have had the mag in a vice with the wires set up to arc to the vice as I turn the mag with a drill, and it does seem that the mag has a dead area between the point where the impulse is tripping and the point where the engine would be running at normal speed. I did de-gunk the weights and impulse parts and oil them lightly and I thought that fixed it, because right after that is when I got it running. I have video that proves it will run. LOL But, now it is right back to doing the same thing. I guess the points should be alright, but I have heard weird symptoms from condensors before.

Your thoughts are welcome on the mag.

#5 mrf1002u OFFLINE  

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Posted December 02, 2012 - 08:40 PM

P.S. Sometimes it will kinda half run for 4 or 5 seconds but never quite transistion from that slow hit, hit, hit, hit thing over to getting off of the impulse and over to full RPM's.

#6 DougT ONLINE  

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Posted December 03, 2012 - 08:22 AM

I like to see the mag jump at least 3/16" gap outside the cylinder. I've got an engine that is touchy on the fuel and it starts like you describe. What about a vacuum leak at the intake manifold to the cylinder? Maybe a valve that doesn't seat right every time? Another thought would be to advance the timing a little bit. I'd have to, look and see if that's possible or not. I know they didn't take an extended reach plug and I don't think the heat range will make that much difference on start up. A higher heat range will keep plugs from fouling as easy in our show pieces but I've never had an instance where I thought they started easier.
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#7 mrf1002u OFFLINE  

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Posted December 03, 2012 - 09:54 AM

It might come close to jumping a 3/16" gap, at least 1/8". I have not tried new plugs yet either. I have ordered them. I know plugs will sometimes fire in air, but not under compression.

I have not checked for a vacuum leak, but it ran ok when it started. I guess it would be more sensitive at starting RPM though.

I have tried the timing everywhere from 20 BTC or more, all the way to TDC. It does seem to want to start more often nearer to TDC as mentioned in Mark E. Bookout's site (http://web.mst.edu/~.../twin_page.html).

As far as the valves anything is possible, but since it ran for the first time, it seems to have gained compression and I would probably notice the difference in cranking effort if one cyl had a valve sticking.

I think my problems could be amplified by the fact that both carbs I have tried had minor flooding issues. I now realize that I may not have a fuel filter in the line. I did not want to disturb the sediment bowl because they can be very leaky after you do, and it may not have the screen in place. It also just hit me that ITHINK I got it running AFTER the original Zenith carb started leaking fuel around the high speed needle nut (stripped out). It was dripping pretty good so that would have prevented the flooding issue and leaned up the mix. The Flojet was flooding too, so maybe it is just too rich to start. I am going to put a filter in the fuel line and flush the Flojet out again before I try it next time.

As far as the mag, it is equipped with an impulse. Theory question here. Should a Wico A mag have spark on both cylinders,when it reaches just enough rpm to bypass the impulse? I just assumed it should. If not, then my mag may be fine and I just need to address my fuel problem. That needle and seat in the Flojet carb seems a bit iffy to me. The needle just kinda flops around in the hole and it seems it would be hard for it to hit the little viton "donut" seat just right. Every carb I ever saw, the needle was a fairly close fit to the side walls of the seat, to keep it lined up. This one has room to flop around.

Thanks!

#8 DougT ONLINE  

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Posted December 04, 2012 - 10:31 AM

I went out and checked my 34 twin last night and guess what. It has Champion X plugs in it. I was thinking they were 18mm pugs . I guess this is proof I shouldn't think! It's been too many years since I played with a twin. Are your plugs still 1/2 inch pipe thread or are they different being newer?

I had a couple thoughts on your mag. Are you using copper core wire and not the new resistor wires? Sometimes if a mag doesn't perform good at slower speeds, it is due to weak magnetism. Sometimes recharging the magnets makes a big difference. I've also had luck by varying the point gap one way or the other. The other woud be a weak primary side of the coil. You should see somewhere in the 1.5 ohm range.

A lot of time on these old engines its a matter of getting the right combinations. After you know what it takes to get it started, it will go everytime.

#9 mrf1002u OFFLINE  

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Posted December 04, 2012 - 12:17 PM

I went out and checked my 34 twin last night and guess what. It has Champion X plugs in it.


I have not looked at the seats yet to see. I wonder if they possibly used different plugs as time went by.

"Are you using copper core wire and not the new resistor wires?"

Brand new copper wires from Brillman. The old ones were also copper.

"Sometimes recharging the magnets makes a big difference."

I watched some video online about that stuff. Figuring out the north and south poles of the armature and using part of an old battery charger transformer to remagnetize it. Might be interesting to try, but not sure If I want to go that far. I am torn on keeping this mag or finding one of the later model FM J mags with the right numbers. I like original, but I prefer the FM mags. I am going to get one of these carbs perfectly correct with no leaks or flooding before I do either of those options. It ran before, it SHOULD run again. I have ordered a new carb kit for both. The Zenith needs attention and the Flojet has a needle and seat that just seems wrong to me. It was rebuilt before, but who knows if they used the proper kit or even the right parts from the kit.

Looking forward to the " it will go everytime" part of the process. I have the rear gearbox replaced and now it won't start so I can move it around. :-(

#10 mrf1002u OFFLINE  

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Posted December 04, 2012 - 12:20 PM

"Rear gearbox" !!! LOL. I forget this used to be a two wheeler sometimes! I meant left gearbox. LOL

#11 mrf1002u OFFLINE  

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Posted December 06, 2012 - 01:41 PM

I can now tell you for sure that at least MY tractor does NOT take Champion X (25, 525) plugs. They are too big. I tried one and even the unthreaded portion of the plug nearest the electrode will not go past the threads in the hole. Even if it did, this is a one inch reach plug and I'm not even sure it would go in without hitting one of the valves. However if the reach works, it might be an easy way to fix a stripped plug hole. Just drill and tap it up to the 1/2" pipe thread.

Mrf1002u

#12 mrf1002u OFFLINE  

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Posted December 10, 2012 - 11:28 AM

So.....I now have 2 brand new Champion 525 (25) plugs that I do not need. They weren't even screwed in, because they didn't fit. I would like to get some of my money back, so if anybody needs them. I will take $20.00 for them, INCLUDING THE SHIPPING, anywhere in the lower 48 states. (Priority Mail Flat Rate Box.) That's seems fair to me, I have about $30.00 in them, including the tax. I see them on ebay all the time for $15.00 each, + shipping.

Let me know if you want them. PayPal or a POSTAL SERVICE money order please.

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Edited by mrf1002u, December 11, 2012 - 08:33 AM.


#13 75917591 OFFLINE  

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Posted March 09, 2014 - 01:01 AM

So what plugs should I use?

#14 DougT ONLINE  

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Posted March 09, 2014 - 01:17 AM

So what plugs should I use?

Which ever ones fit the holes in your head. Like noted earlier in the thread, some used a 1/2 in pipe thread plug and some didn't.



#15 pharmall200 OFFLINE  

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Posted March 17, 2014 - 01:17 AM

Hi, I have several twins.  The older model that came with the iron heads used the old larger plugs like those used in the Model T Ford.  Later models used aluminum heads and used the smaller modern plug.  I do not have my literature at hand but if I remember correctly it was some time in 1940.  I have used Champion UD-16 with success but like those manufactured longer ago from old dealer stock than brand new ones.


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