Spark Plug blow by - Is my 2N head dead?

allenlane

Member
Just got my 2N running after sitting up for 3-4 years. I'm not getting any smoke at all out of the exhaust pipe, but I can see a little oil build up around the base of the #4 plug. I took it out and can see the plug seat has rusted slightly so the seat is not sealing under the plug. I've not done a compression test yet, but that #4 plug is pretty black, so I likely will need a ring job in the future.
Question - Is my head shot? Any way to fix it?
 
Are the plugs 437 autolite and do all have gaskets/seal ring on them. With no gaskets and loose will leak around them.
 
They are HO12's and #4 is the only one leaking. I tightened it down much more than the others and reduced the leaking substantially. That head design, with the recessed plug cavity must be conducive to having moisture and junk settle in there for tractors that live outside, as many of them do.
 
Get a thread chaser and clean the threads. Make sure the plug is seated correctly and has a gasket.

If the threads are wallowed out, you can fix it, or just replace the head.
75 Tips
 
The 14mm plug, original FORD spec'd for Champion H10, now can use a hotter plug, Champion H12 (numbered 512 now)or the equally good Auto Lite 437 plug. Gap spec is .025" -.027". The lug thread size is METRIC -14mm x 1.25mm (thread pitch, TPI, Threads Per Inch)) -DO NOT USE ANYTHING ELSE!!!

Tim Daley(MI)
 
What am I missing? I'm talking about the honed section of the head that the plug washer seals/seats against being rusted out /worn...and you guys are talking about threads. The threads are fine and yes, of course there is a washer. Doesn't sound like a worn head is a common problem.
 
(quoted from post at 20:26:30 12/04/17) What am I missing? I'm talking about the honed section of the head that the plug washer seals/seats against being rusted out /worn...and you guys are talking about threads. The threads are fine and yes, of course there is a washer. Doesn't sound like a worn head is a common problem.

If the threads are damaged it is possible the plug is not seating all the way, which would cause it to leak. the washer should crush causing it to seal even on a corroded surface. IMHO
 
If it isn't too far gone, It might be worth trying a real, solid, copper plug washer, and anneallng it by heating it up red hot and dropping it into water. to soften it so it will make a better seal. This is
standard practice in the light aviation world and perfectly safe. Don't be shy about annealing it several times in a row. If it works you probably will have to replace the washer/gasket anyrtime you
remove the plug, no problem, the copper gaskets can be annealed many times.

Otherwise your best bet is to take the head to a decent automotive machine shop and see what they can tell you.

You'd think it would be a common enough problem that any decent auto machine shop would have a spark plug seat refacer but I can't recall ever seeing one. You could mill or turn it, but that could
easily end up costing as much as a new head.
 
" Spark Plug Hole Conditioning Tool "

Interesting. I've always called them spark plug thread chasers. Hence my comment " Get a thread chaser and clean the threads."

Learn something ne everyday around here!
75 Tips
 
(quoted from post at 16:34:18 12/05/17) " Spark Plug Hole Conditioning Tool "

Interesting. I've always called them spark plug thread chasers. Hence my comment " Get a thread chaser and clean the threads."

Learn something new everyday around here!

That is more than a thread chaser - it has a (crude) spring loaded seat cutter in addition to the thread chasing section.

BG_Spark_Plug_Tool.jpg


This is an ordinary thread chaser.

TOH

41GAKZC0DkL.jpg
 

I think Jim and Hokie have hit the nail on the head. All I need is about 1/16 to get a flush seat. Is anybody worried that I don't have enough clearance with the TDC of the piston?
 
(quoted from post at 21:54:18 12/05/17)
I think Jim and Hokie have hit the nail on the head. All I need is about 1/16 to get a flush seat. Is anybody worried that I don't have enough clearance with the TDC of the piston?

I'm not worried. I'd say there ain't a snow ball's chance in he!! that the seat cuttor on that BG tool will remove 1/16" of cast iron :roll:

TOH
 

Put a new plug in it with a new washer before you go fudgen up sum"N that's not broke. I think Dell has posted the correct way the washer goes I put'em on and don't worry about it...

The washer is a pizz poor seal to start off with I have seen'em leak and bet a bunch do if folks would check them... I would be more worried about the oil you see leaking...
 
Good news today. Finally got around to doing a compression test. Got 110 psi on every cylinder, with only the #4 leaking off. Don't know if it's a valve or rings, guessing rings since plug is pretty oily.
 

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