Hmmm
 

Nice machine work.


Most people find it cheaper to use these...

This price is per each glow plug
F1100-117786 Glow Plug Bosch IN STOCK

I am not sure. I beleive it is after 1985 though.
There were some thread on it about 2 years ago.

I know my 84 300D does not have the Afterglow feature.

Looking at the retrofit Pencil Glow Plugs it looks like when they are installed there is going to be more empty area/volume than before. That extra empty space decreases the compression ratio.
He had the Equipment, the skill and the willingness to spend the time to do the project.
The result eliminated the extra dead space using the retrofit Plugs would have created and if there is any hollow area where the Filiment/Loop is on the Stock Glow Plugs his mod might have even increased his compression ratio slightly from stock.

;) You got it!

Well here are the volume numbers that I came up with during design.

Stock Loop Plug = 1.34947637cc:)

My Adapter and Pencil Plug = 1.63173543cc:D

Bosch Conversion Pencil Plug = Estimated @ .672387455cc:(

:)What is the thread size of the large plugs , 18x ? 1.5 ? . Your design pretty much imitates the plug layout in the small plug heads and glow plugs not only heat the intake charge air but also warm the head in cold weather to keep the engine running.
imagine ,if you will the heat soak from a glowplug into the heads casting when they are operating.

After glow relays are common on the OM602 powered cars . my 2004 Ssangyong MB`140D had afterglow. it made for instant starting and cleaner running .

Cheaper than the stock plugs but no longer in stock...:(

I was going to make the adapters, but found the ones Hunter has. I don't do much in metric, and my lathe does not have metric threading ability. 1930's Pratt & Whitney.

Had not thought of the differance in volume.

My Lathe also has no Metric Threading Gears and even if it did my 2 semesters of High School Machine shop back around 1968 showed that I was not very good threading on the Lathe.

When I made my Prechamber Puller and Ring Remover tools I cut the cylindrical section on the Lathe and used Split Dies to do the Metric Threading.

I also noticed that where I used to work the 2 Machinist that were in front of our Diesel Shop in the huge Building; always ran a Threading Die over their Threaded Shafts after they had done Threading on the Lathe.

sorry if this sounds stupid but what am I missing ? A replacement for loop type plugs to larger pencil (14 ? mm) exists why fabricate adapters to use thinner plugs in older engines ? I replaced my loop plugs on the 74 240 D to the pencil by buying this kit. Sure after conversion your glow indicator inside does not work any more but you can time it yourself and start the car. Example ebay item 200567616087

Answer
 

Fastlane: Glow Plug - Duraterm
http://catalog.peachparts.com/item.wws?sku=W0133-1629394


This is the (four) fast glow conversion kit "ADD 1 extra glow plug for 5 cylinders"
F1101-88322 Glow Plug Kit Bosch IN STOCK



FYI:
glow plug conversion kit thread links (Loop to Pencil)
http://www.peachparts.com/shopforum/diy-links-parts-category/151959-glow-plug-conversion-kit-thread-links-post1155675.html



.

It is in the Thread. The Filiment/Loop type Glow Plugs take up more Volume in the combustion Chamber than the 18mm adapter Glow Plugs do. So when you use them you lose a slight amount of compression ratio.

One of the things the Guy who made the adapter wanted is to retain the same amount of combustion Chamber Volume and there by not decreasing his compression ratio.
Remember he is a experienced and trained machinist who had the equipment he needed to do the job. He did it for himself and posted the info for our information.

The pre chamber puller is very close to I think it was 20 threads per inch, close enough that I got away with threading it. For non precision work I will often run a die over the threads too, but I do not do this when a tighter thread is needed.

Om616 I am assuming you calculated the compression differance? how much overall in psi or percent?

I measured one this morning,it's 18x1.5 mm and the pencil glow plugs are 12 x1.25mm . Common metric threads .I just need the time to make some of those for myself ..;)

For 617 Engines
Prechamber PULLER Threads- 22 X 1
The threaded part that tightens the tool;RING REMOVAL TOOL- 24 X 2 (Same as the outside threads of an Injector.)

Split Dies are less precise but offer the chance of making the threads tighter.
However, I do not think the Filament/Loop type glow Plugs seal on their threads.
I believe thaty they seal on the sholder that the read arrows point to.

Without any compression calculations you can see by comparing the pics that the original Filamant/loop style Glow Plugs take up more space in the Combustion Chamber than the updated Glow Plugs.
So, using the updated Glow Plugs has tiny decrease in the Compression. Since, the updated Glow Plugs more than make up for the compression loss by putting out more heat the slight compression lost is not an issue.

But, some people are more picky that others about that stuff.

18x1.5 mm is the size of the Threads on some of the older Car spark Plugs. It is also the size of the Threads where the Fittings screw into the Oil Filter Housing on the 617.952 Engines (and the Tap you use when you do repair so that the Steel Nipples can replace the stripped Nipples on the Oil cooler).