What could have happened? H12 Plug issue-Dell?

Bfisherman11

New User
I bought Champion H12"s and set the gap to .025 as recommended on this board. I am no novice but this was strange.

I removed my old plugs (AL82=Motorcraft). I put in the H12"s and bam it would not start. Eventually it did but something was wrong.

I pulled the H12"s and the ground wire/side electrode was flattened out........ It looked like something hit all 4 and flattened them out. I should have compared them at that point to the AL82"s but I was so shocked I just put the AL82s back in. As I suspected the old 1941 9N fired up and ran well.

So what could have done this? I have never seen anything like this ever. Oh, I did have the gaskets on so that if anything would have kept the plugs further out. Also I did not over tighten.

Thanks,

Bill
 
Well #1 you got champs instead of what most say to use as in auto lite 437s. You do know champs are now made in the land of almost right so yes you got almost right parts
 
why aren't you running autolite 437's? Front mount gap is .015 side mount on the later 50-52 side mount dizzy is .025. I would believe if the plus are getting smooshed the pistons are hitting the plugs.
 
Got a picture of one? I'm curious as to how that happened.
.025 is the right gap for the plugs, H12 would be the right
Champion plug for your 9N if you were buying Champions.
No way a (whole) piston is going to hit a plug in these flat heads.
Maybe someone else has seen this, but I haven't.
I'd be very curious to know if it was just bad parts.
 
my bad I was talking about gap on points! That's what I get for getting that damn tractor running today!
 
Don't feel bad, I've mixed them up too. :)
I get even more confused when I work on different brands.
They all basically work the same, but the specs and
idiosyncrasies can be far different!
 
"No way a (whole) piston is going to hit a plug in these flat heads."

That's correct, but a VALVE might IF the sparkplug is long enough, 'cuz they are located over the valve area NOT over the piston!
<img src = "http://i1.ytimg.com/vi/BBoSDb9QyNY/hqdefault.jpg">
 
Not sure about AL82=Motorcraft. Is the electrode shorter on them? Maybe the head had been shaved to much so the PO was able to get it to work with a plug that has a shorter electrode. If the AL82 is working stick with them. If I remember right shorter electrode means colder plugs. But hey, use what works for you.
 
The gap on my old AL82's was .025.

I found some AL82F4's, will these work? Sounds like it.

After the issues with the H12's I am worried about trying anything else, even the AL437's.

Bill
 
Check the reach of both plugs.Not just the threads but the overall length from the gasket surface to the electrode when gapped at .025.Overmilled heads can problems with pistons striking heads.Spark plugs are over the valve in that engine.Quick fix but not the best, 2 gaskets per plug.
 
As others have said check the head to make sure that the head has not been overplaned. I used to plane these heads and too much can be taken off. You may be in the market for a new head if that has been done. Also check the threaded portion of the plug, the Champions might be too long. And as Lisa K said only use Autolite 437 plugs properly gapped. Champion plugs are not today what they were in yesteryear.
 
This is a pic of one of the plugs. A couple were worse.
a130309.jpg
 
Wouldn't it be more likely that the plugs hit the block between the valves when they were put in. Even with terrible valve guides, it's hard to imagine A valve hitting A plug, let alone all four. If the gasket was missing, and/or the threads too long, they could easily hit the block between the valves.
 
might be a heavily milled head, that had been relieved to allow clearance.. but that with long plugs allows them to smash into the block when tight..e tc..
 
From the look of this cut away picture I'm not sure the head could be shaved enough for the valves to hit the plugs.


Gary (Or)
a130312.jpg
 
Bill.........dunno.......besides heat range, sparkies have threaded shell specs; yer 9N flathead is spec'd fer 7/16" reach. There are also 1/2" reach and 3/4" reach. From yer description, somehow yer H12 has 1/2" reach which would extend yer sparkie tip further into the engine which would allow yer VALVE to pop-up and BEND the GROUND electrode. Surprizingly enuff, ALL sparkies threaded diameter is 14mm and 19mm (3/4") hex head fer wrench removal. While yer N9 flathead was originally spec'd fer H10 Champions, with todays "no-lead" gasoline, a "HOTTER" plug is recommended, and H12 is "hotter". ...BUT... because of quality control issues, we recommend AutoLite 437's gapped 0.025". ........HTH, Dell, yer self-appointed sparkie-meister
 
Would you believe with all 4 plugs smashed like this my 9N still started? It was hard to get it to catch but it did. These are unreal tractors. Oh I am still at 6V as well....

Usually even with sitting all winter it turns twice and starts every time. Sure it leaks a little oil, no live hyd etc but I bet the new tractors being built now won't be running like this when they are 72 years old.
 
They are made in Mexico and have had problems with the shell breaking off in cylinder heads.Happened to me on an Olds V8.Most of the threaded part stayed in the head.It came out easy and showed most of the break was old.Had to be overtightened.Ive had some hard removals but never had a Champion plug break off before that one.I have plans to tap some some half inch steel 14mm and do a torque wrench test to find the breaking point of old and new Mexico plugs.Too much to do getting ready for winter now.
 
Ill repeat.Measure the reach of the old and new plugs.The shorter reach plugs may have been put in the engine for a good reason.J series Champions have a shorter reach.Its a simple matter to compare the reach of the plugs that were in the engine to the H12s.No need for ideas that the plugs are hitting the piston or block.Those who say this dont know that it cant happen in this engine.There was an aluminum High compression head sold for this engine that could be different as to spark plug location.
 
It's a picture of a 2N that someone cut sections out of as a demo tractor. I found the pictures on this or the other discussion board some time back.


Gary (Or)
a130469.jpg
 
If you pull the plugs and look in the plug hole (especially with new valves) you can easily see the valve overlap in the plug hole.
I must be getting senile, as I've looked and seen before. :lol: The H12 pic posted does LOOK too long in the threads. The blank area between the top of the threads and the gasket shouldn't be there. That's where it LOOKS LIKE the extra length would be. If the reach is too long,I'd have to take it back and carry on til they at least alerted the manufacturer. No telling how many engines they could damage. Lucky you didn't bend some valves.
 
(quoted from post at 03:01:02 10/01/13) Ill repeat.Measure the reach of the old and new plugs.The shorter reach plugs may have been put in the engine for a good reason.J series Champions have a shorter reach.Its a simple matter to compare the reach of the plugs that were in the engine to the H12s.No need for ideas that the plugs are hitting the piston or block.Those who say this dont know that it cant happen in this engine.There was an aluminum High compression head sold for this engine that could be different as to spark plug location.

I worked on a few Pontiac and Chevy engines in the past. Remove all of plugs and place a short wooden dowel straight down in one of the spark plug holes. Slowly spin the engine by hand where the valve should move the dowel up and down and measure the max and min heights of the dowel. The max height measurement is just beyond the max reach that the spark plug can be without hitting.

Keep in mind your max reach can be different then specs due to:
Milled heads
Thin gaskets
Custom domed valves
Loose valve train.

There is a spark plug adapter called anti fouling something or other that screws into the head and the plug screws into it. It will buy you some reach.
 
Worked on a lot of flat head V8s.Remembered wrong.The valve lift could be checked with a wood dowel.
 

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