More About Prechamber Inserts

[libbydiesel]

I was inspired by some recent events to further investigate precombustion chamber inserts.

Here's a chart of the gathered info (some of which is redundant):

[Casting number]	[1.6 or 1.9]	[lifter type]	[turbo or n/a]	[flange dmtr]	[magnetic precups]	[cracks]	[dimples/triangles]
028103373j	1.9	hyd	Turbo	32mm	Yes	NO	No
068103373D	1.6	hyd	Unknown	32mm	Yes	NO	No
068103373T	1.6	hyd	Turbo	32mm	No	Yes	No
068103373T	1.6	hyd	Turbo	30mm	No	Yes	Yes
068103373T	1.6	hyd	Turbo	30mm	No	Yes	Yes
068103373N	1.6	Solid	Turbo	30mm	No	Yes	Yes
068103373N	1.6	Solid	Turbo	32mm	No	Yes	No
068103373B	1.6	Solid	N/A	32mm	Yes	No	No
From Gizmoman
028103373M	1.9	hyd	N/A	32mm	No	Yes	Yes
From Luckypabst
068103373D	1.6	hyd	N/A	32mm	Yes	Yes	No

There are some interesting data points I would note.  1.6TD precups came as BOTH 30mm and 32mm with both mechanical and hydraulic heads.  The magnetic precups (presumably steel rather than inconel or stainless) are NOT cracked.  This is especially interesting to me because the last head listed (suffix B) was a very old 1.6 head with 11mm head bolts that showed to be just hammered.  There were big cracks between the valves and even cracks between the two center exhaust valves and the precups.  Despite all the obvious wear/heat, the magnetic precups were flat and had no cracks.  That isn't definitive, but leads me to believe that steel precups would be BETTER than inconel.

Altrom(Napa) sells AMC brand precups for the AAZ engine for $27. Part # 028103391M.

Eurocar Togliani in Italy sells precups for the 1.5, 1.6 and 1.9 engines.  I just got a quote from them for 24 euros each plus approx 40 euros for shipping for a couple sets.  That brings them up to approx $40 per precup.

RockAuto lists prechambers for the 1.6 non-turbo engines and yet the dimensions listed are the 30mm and 25.4mm diameters which match the TD inserts and NOT the n/a ones.  They list them for approx $13 plus exorbitant shipping - $60 for a set, but unfortunately, when added to the shopping cart they post up a note saying they are not available and delete them from your cart...

I found THIS site that lists prechambers for the 1.9 but have e-mailed a while ago with no response.

I am planning on e-mailing Topline to see if they will sell any prechambers or have any source they could direct me to.  

Anyone else have potential sources?  Anyone have the capacity to machine new ones?  

I'd welcome anyone to look through their parts stash and list up the same specs for any heads they have.  I'd be happy to add them to the table.  

[Gizmoman]

I have four I removed from the head. #3 was loose and I removed the others in search of water-jacket issues - none found.
The circular marks are just soot - not grooves. These things are harder than hammered cat turds.

They are non magnetic and have "CHU2028B" stamped in the side. No cracks, 1.0915" OD .

The head is complete with the typical small cracks between the valves. I bought a new KS head complete.
I believe the engine is an industrial 1.9 out of a forklift but I'm not positive - just guessing.
The piston pins are smaller than stock. I mention this because the cam may be a different grind as well.

[libbydiesel]

Thanks for the info.  You'd have to buff off the carbon/deposits to see whether or not they are cracked.  What is the flange diameter, flange depth and main cylinder diameter?  What is the head casting number?  Can you see if the new KS inserts are magnetic or have you already installed the head on the block?

[Rock3tman]

Thanks for the summary Andrew; back in 2011 when I got my 1.6TD sets from Eurocar Togliani, I contacted AMC in Spain
as prechambers were listed in their catalog as separate items - - but they replied that the weren't available except in a completely
new head.

I'll measure my old VWAG ones and post up later

[745 turbogreasel]

Might be interesting to  measure CC's and  opening size too.  I know Gm changed around the openings with different power outputs.

[fatmobile]

 What's the best way to remove prechambers,
without cracking them?

[libbydiesel]

Best to use a brass punch down through the injector opening.  Aim toward the wall rather than the edge of the inner lip.

[burn_your_money]

Some guys tape the opening shut then fill it with salt then use the largest punch possible through the injector hole.

[ktzdsl]

When I was searching for precups, I found the Eurocar products as you did, but the cups were slightly larger that stock; 0.5mm if I recall.

In addition, Federal Mogul UK and Belgium, I think listed 1.6 precups for the GTD engine in the Audi. (engine code RA/SB) and I think listed them as stock plus an oversize. See info below from a previous entry on the forum..

Having just received a head with cracked chambers I went on the hunt for some new ones. I looked in the Federal Mogul UK electronic catalogue for them and found some for the 1.6td head under the Audi 80 1.6td section. They are for the SB GTD engine and there are two different sizes listed but only one is available in STD size and 0.5mm oversize. My local supplier says he can get them in from Belgium for £12 each. Link: http://www.fmecat.eu/selProd2.asp?make=5&model=%20&engine=4211~SB&litre=%20&prdgrp=4&langID=1&TsVer=&engseal=0
Before I order I'm trying to establish if they will fit correctly, Federal Mogul lists the dimensions which seem to correspond with some measurements taken from this thread:
http://www.vwdiesel.net/forum/index.php?topic=2329.msg17375#msg17375

[Gizmoman]

Here's a shot of one "buffed" pre-cup. You were correct, you can't see the cracks till it's cleaned up.


Flange diameter - 1.2565" [31.9151]

Flange thickness - 1.1595" [29.4513]

Overall height - 0.6685" [16.9799]

Barrel diameter - 1.0915" [27.7241]

Small protrusion on the barrel OD directly opposite the port (would be upper left in photo)
CUH2028B cast in barrel OD to the right of the port.


I didn't clean them all but assume they each have similar cracks.
Here is the head number these came out of:


The KS head has non-magnetic cups as well. However, there is no indentation in the face to the left of the port (like the one shown in the pic). The head appears to have been surfaced with the cups installed as I can barely make out the cup edge itself.

May I ask what has led you to this extensive research?

[libbydiesel]

May I ask what has led you to this extensive research?

This happened less than 3,000 miles after a complete rebuild and was a significant amount of inspiration:





I also recently purchased a used head that is in very good condition aside from the precups having small cracks.

[Gizmoman]

  Man, what a disappointing event. I hate to sound so selfish but It's not much of an an inspiration for a guy who is spending mega bucks on what is becoming a two year rebuild.
When I add this to the dropped cup on theman53's build and my loose cup on #3, I have to question the effort. When I bought the van it had the 1.9 in it and I figured, diesel, strong, last long time, good. Six months later it was attached to an engine stand. I sprung for the new KS head because of the loose cup on #3 and a questionable area near a water jacket port. From what I have been reading, within a few months the new KS will have cracks between the valve seats and could possibly drop a cup into the barrel - this sucks.

Obviously you are looking for a solution. I will be watching this thread closely and offer anything I can to assist.
I have a Lagun knee mill and a Graziano SAG lathe - just don't have a lot of time .

[Luckypabst]

Here's some more info for you, Libby...
Looks like you already have this in your database, however

Casting #0X8 103 373D (X digit is indeterminate due to casting flaw, assumed to be 6)
Hydraulic, NA 1.6
All cups magnetic
All cups cracked
32mm diameter
No dimples.

I'm about to start slicing this head so it stores more easily in my scrap bin.

Chris

[Gizmoman]

Another interesting thread - http://www.vwdiesel.net/forum/index.php?topic=32562.msg300809#msg300809.
Didn't read the whole thread but I do recall several posts about a steel head.

Aluminum and inconel - not too good together in a high heat application IMHO.
May be a silly question but I wonder if they cast the head around the cups? The ones I removed have a tiny nipple on the side which would just broach out a meaningless groove if they were pressed in later.

[libbydiesel]

Dropping precups isn't a common issue.  Gizmo, I think with your new KS head you should be fine for many thousands of miles, especially if you are very moderate with max EGTs.   If it's something that has you losing sleep, your block, crank and rods will fit with TDI pistons.  Add an AHU head, injectors, timing covers, pump bracket and mTDI pump and you no longer have precups to be concerned about.  Another upside is you'd gain 10-15% in fuel economy.  A downside is that your stock vanagon gearing would stink.