ford 1320 - overhaul advise

I am currently working on an overhaul of my ford 1320 tractor (Shibaura 1.3L 3cyl diesel). I am about to bolt the head back on (for the second time) and I noticed that 1 of 3 glow plug holes have a plug & vent shown here:


I think the intend purpose is to protect the head gasket & cylinder walls from the direct heat of the glow plug. I think this because of the damage seen on my original head gasket & the one I ran for <15hrs after the rebuild.
[img]https://photos.app.goo.gl/bFMZePe6WM7AFX0B3https://photos.app.goo.gl/1Fv1tobl9vidSYA03[/img]

But the fact that the original is damaged on #1 & 3, tells me there were no plugs to begin with (ie I didn't loose them). Additionally, the 2 photos I have from the manual both picture plugs in all 3 glow plug ports. This begs the question, why don't I have them? were they intentionally not installed? was this a manufacturing error?

After seeing what it did to my head gasket after only 15hrs & very minimal glow plug use, I am leaning towards machining plugs to protect the rest. Does anyone think this is a bad idea? if so why?

turning the plugs is well within my skill set, however, I lack the expertise to know from what type of cast iron these should be made?

Those plugs are the pre combustion chamber and there needs to be one for all 3 cylinders.

Mark

Here is a pretty good video explaining how it works.

Mark
Indirect injection

yeah I got that now....but can't seem to source replacements anywhere. trying to figure out if I can make them, thoughts?

They are not serviced separately, you would have to replace the head. I would think you would need to remove the other one to use as a pattern if you were going to try and make some.

Mark

I have pulled the one out, I am reasonably certain I can make these, just unclear on material selection.


any idea why they are not serviceable?, its not as if they are integral, or even pressed in so I see no reason they shouldn't be serviceable....

I don't know why they are not serviceable but I would expect them to be of a fairly good steel like a valve seat. I've never removed any and never had any fall out but I would think they should be a press fit.

Mark

I am reasonably certain the original is cast iron ( and it slides in & out easily, but its not a worn fit)....i thought stainless steel would hold up nicely, certainly wouldn't shatter like the cast iron ones did ...my concern with steel or stainless steel was differential thermal expansion between the precup & the cast iron head, thoughts?

I don't know how much difference there would be in the expansion rate. They do need to be tight enough to not fall out while installing the head. I would be inclined to look for a used or reconditioned head as I would not have the means to make new ones.

Mark

You definitely need 3. I just have
experience on a Moline. Have seen one get
loose would clatter like a rod bearing
letting piston hit head. I would make
them tight. Tool steel should work. The
pistons are aluminum or steel.