Paranoid about dropping a prechamber - page 4 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.
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#45 by Mark(The Miser)UK on 24 Aug, 2011 09:24
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I think it was about 220 Grit.
I didn't have a floor sander roll to hand. The strength of the cloth of the floor stuff is such that I may have had a problem keeping it flat. Maybe there is some on a roll that is slightly less 'heavy duty'
I think I only had one join give me brief trouble, but it glued back with that spray adhesive.
I did it completely dry, and quite slowly, so I didn't have any heating issues.
It did amount to about 72 pulls, split up into 12 lifts to photograph and 24 raises to blow/brush swarf out. I think the bed was about an inch too short to completely avoid the head overlapping it's footprint, hence the lifting of the head to blow the 'filings' away.
I found the symmetry of the areas as they were being levelled quite fascinating...
I used new bolts for this event, but knowing the history of the bolts reused them last year. Not sure if I'll reuse them a third time; but I may run some tests on them next time
Looks like you did a nice job! I know silicon carbide paper is black. Is Carborundom red? You can get floor sander paper from a roll so you don't have to stagger 8.5 x 11 sheets and eliminate the edges. What grit paper did you use? I think the floor sander paper in fine is somewhere between 120 to 220 which is close to the finish you want on the head. Did you do it wet or dry? How many times did you re-use the head bolts?
http://imageshack.us/g/222/tenthabradeka0.jpg/
Here's a few pictures of the various stages of my 'hand' abrading my head some 3 years ago. Done due to a head gasket failure.
Things to note are:
My use of carborundum paper on 3 layers of plate glass, padded with sheets of newspaper to compensate for any 'sag'
My use of a counter weight to offset the weight of the manifolds.
My leaving of the manifolds on to avoid pre/post abrading, warping of head, and flexing cam holders.
Each head pic denotes six traverses along the paper.
Every 3 slides, head lifted and filings brushed away. I found this neccessary, else build-up of inconel grit scoured the rest of the head.
Note symetrical abrading. Note part of head warping is for the inconel to twist and sink into the head.
Note the abrading took the ears off the ex manifold too.
No issues in 3 years.
Took head off last year to do the rering.
Reused bolts, as only torqued to 45 deg or less each time, as and when each bolt hit the plastic range. -
#46 by 92EcoDiesel Jetta on 24 Aug, 2011 16:33
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Very cool! How much was the warpage before you sanded it down?
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#47 by Mark(The Miser)UK on 24 Aug, 2011 18:24
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Very cool! How much was the warpage before you sanded it down?
Between 3 and 4 thou.
I think main issue was a sudden catestrophic gasket failure, possibly caused by corrosion of the metal band gasket edge. Top hose burst with a 6" slash. Exactly the same as on another Quantum, and neither installed by me.
If I need to do it again, the only changes, would be to be sure I counterweighted the manifolds more exactly, and aim to take off no more flesh than neccessary.
Believe you me, I became mesmerised with the symetrical patterns forming
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#48 by gldgti on 24 Aug, 2011 19:29
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Flawed.
The file is going to be softer then the inconel, and the weight required to press in the tooling to form the knurl (not cut/scratch) would be immense. Crude cold forming, no?
Props for the drawing, the engineering department at my previous employer could have used you. Much better then a dootle on a napkin (in crayon, even) I would normally get.
Peen them in if your worried, grease them and slap them in if your like most on here. Used THE PROPER injector/nozzle for your make of car (tested) and be on with your day.
.02
I agree you would have little chance of knurling a precup that way, but seriously you guys should try filing a precup with a file... it does work. I'm tired of hearing that "inconel" which is a general sales term used to classify a huge range of alloys, is "bloody hard" when the only thing most people know about it is that its harder than the aluminium head casting, which is "bloody soft"!
thats mega cool head sanding DIY btw. -
#49 by monomer on 25 Aug, 2011 16:01
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Hand filing will not help all to much.
It might help hold when peened, but thats about it.
Knurling is a forming operation that presses material into a knurling tool. The pressing causes the texture, and also bring up to diameter, usually upwards or .005 (depending on material/depth and type of knurl)
It's a bit touchy to do on a manual lathe on steel, let alone an exotic metal. -
#50 by R.O.R-2.0 on 27 Aug, 2011 12:34
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Hand filing will not help all to much.
It might help hold when peened, but thats about it.
Knurling is a forming operation that presses material into a knurling tool. The pressing causes the texture, and also bring up to diameter, usually upwards or .005 (depending on material/depth and type of knurl)
It's a bit touchy to do on a manual lathe on steel, let alone an exotic metal.
oh, i totally believe you..
thats why i said on my post:
"it would work IF you could figure out how to do it" -
#51 by Mark(The Miser)UK on 27 Aug, 2011 16:43
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Here's my stab at a cure:
If your cups are loose, remove them, and then in 90 degree intervals file a bevel into the face edge. Tap the perimeter of the hole with a bodywork hammer to tighten hole slightly.
Reinsert cup, then with a suitable punch, push the head material slightly into the bevel. I guess you could do 3 or 5 etc, but, should you do too many and need to remove the cups for experimentation purposes such as ceramic coatings, it could make it too hard to remove them again...