1HZ Pre-combustion Chamber Shim Question?

[lelandEOD]

I'm ordering all the parts to have my cylinder head rebuilt and have a question about part #11165 in the screenshot below. The parts diagram shows these pre-cup "shims" but I don't think my head had shims under the pre-cups. I guess it's possible that - if they were there - perhaps they stayed in the cylinder head. But, I've looked at the old pre-cups I pulled out of the head and I see no evidence of these shims.

Can anyone tell me if these shims are required or if they are only used in instances where the pre-cup do not protrude enough from the cylinder head to be machined flush?

 

[lelandEOD]

No one? I found a photo of these shims and they are very thin... like .005"-.010" or so. I'm going to order a set.

 

[serenity]

I got nothing but have you checked what it says anything in the fsm about them?

 

[lelandEOD]

I got nothing but have you checked what it says anything in the fsm about them?

I was getting ready to say I couldn’t find anything in the manual but decided to double check before I put my foot in my mouth. It’s a good thing I did because I found where the FSM specifically lists how to measure each combustion chamber and determine the number of shims required. Do’h!

 

[lynchmob]

I wonder if these shims actually exist. I have not done hundreds of HZ engines, but I have never seen them. They are not in the FSM for B series engines (later models anyway) which use the same type of chamber. The machinist I use says he has never seen a shim in any other diesel he has done that has pre-combustion chambers in the head.

Possibly a factory assembly item only when assembling pre-machined parts. Similar to using incremental sizes on the rod bearings.

 

[lelandEOD]

I wonder if these shims actually exist. I have not done hundreds of HZ engines, but I have never seen them. They are not in the FSM for B series engines (later models anyway) which use the same type of chamber. The machinist I use says he has never seen a shim in any other diesel he has done that has pre-combustion chambers in the head.

Possibly a factory assembly item only when assembling pre-machined parts. Similar to using incremental sizes on the rod bearings.

That’s pretty much the same conclusion I came to. I used a pair of micrometers to measure the thickness of each combustion chamber and they were all within a .0005” of one another and required no shims, per the FSM.

 

[roscoFJ73]

Looks like they are copper or brass.

 

[roscoFJ73]

Engines Australia have this on the fitting of pre cups. The last paragraph says most OE manufacturers recommend a protrusion of 0.04 to 0.06mm, so Im assuming the shims are there to get that measurement if its not there when reassembling the head.
https://www.engineaustralia.com.au/sites/default/files/engine_seb/SB019s.pdf

 

[serenity]

I recall another member on here having issues with precups because they weren’t sitting at the correct depth after a rebuild. Can’t for the life of me remember who it was or what engine it was on.