Prechamber install

[rodpaslow]

I've gone throught the search and just want to confirm - when the prechambers/swirl chambers are put into the head the peening is done to the aluminum part of the head around the prechamber in a star shape?  Correct?  The prechambers are too hard/brittle to peen - just makin' sure. 

A machine shop I talked to when I was looking for the prechambers said to use green loctite.  Is this a good idea too?

[rabbid79]

I have no real experience peening the chambers, but if you are going to do it, make absolutely sure you don't it around the fire ring area.  It should be done well within or outside of this area.  Personally, I'd say outside of the combustion chamber altogether.  The only other advice I have is make sure you have the right injectors with a good spray pattern.  You don't want injectors that dribble fuel in there.  I also wouldn't think you'd want Mercedes injectors in there.

[rodpaslow]

Thanks.  I've got the original TD injectors and they have been worked over by Giles - just back to original specs I think.

[Rabbit on Roids]

the way i have seen it done, they just did the area that the gasket did not touch. just the exposed bit that is actually in the combustion chamber. dont peen where the gasket will be trying to seal. i wouldnt even peen them in there honestly tho, because i know how hard it is to get them in and out of the head. and the only way a precup is going to damage your engine, is if the face breaks off the cup and the cup body stays in the head. and i dont think peening the head will save the engine if the face of a cup breaks off.

so basically, do it if you want, but if your head is in good shape, and you know your cups are good, dont even worry about it. the 4 years that i have been a member of the forum, only one time have i seen or heard of a pre cup breaking. and it was right when i joined the board. ever since then, i have heard nothing about people needing to peen there cups. i wouldnt do it, it adds surface area to the head, and makes it so more heat can be transfered to the head, and may even be enough to create a hot spot.

[rodpaslow]

I was wondering about the gasket,because it looks like it should hold them in.  I removed the ones that had cracks (cracls were roughly 3/4 of way through section of the prechamber, not radial)- removed 3 of them and installing the new ones are loose but, when in place they don't move, but they slip into place by hand, no hammer used.  But like you say the head is in extremely good shape where they fit.  It looks as good as new in the bores.

Thanks, I don't think I will peen them and see how it goes.  I think I will use a bit of the loctite, just for a bit extra help prior to installing the head. 

[rabbid79]

If your chambers are slipping in by hand, it sounds like they're a little loose.  (Someone correct me if I'm wrong.)  Also, don't go crazy with the loctite because you don't want it to act like a thermal barrier.  You want the head to absorb a lot of that heat so you don't melt the chamber.  I wonder if you can pin the chamber to the head with a dowel pin somehow.  I'm thinking drill a small hole on the head surface on the edge of the chamber and the head.  Not in the combustion chamber area, but on the back side.  You don't want that sucker to rotate.  I suppose peening would have the same effect though, so if your chambers are loose, maybe one or two spots on the back side might be a good idea.

[theman53]

Yeah I would at least peen them. I did mine and they weren't loose. There was a thread on here that showed what happens when they come out, basically new engine time.

[rodpaslow]

The prechamber won't rotate due to the dimble in them that lines up with the slot in the head, so no problem there.  So what I'm reading is to use green loctite sparingly and peen the chamber in an area away from the cylinder on glow plug side of the head (area where the head gasket covers it when installed.   If this produces any high spots after peening I will remove carefully with a file to ensure head gasket will seal properly in that area.