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#46
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[RANT] Unfortunately the seller has decided not to play ball. They're using the crappy excuse that the guy at Nural says that 20 grams difference is OK. I know this isn't the case => It is total BS for some lazy arsed good for nothing cock head ham shanker to come up with this oh so convenient excuse where they don't have to do anything. I'm now trying to contact Nural about this. In the mean time I've filled out the special return form on the seller's website but the bloody thing doesn't seem to work. Another convenient occurrence. I'm getting totally pissed off with these third rate bell ends. It is a very simple rule - set out in the FSM - maximum weight difference in a set of pistons = 10 grams. Not any other number that might be convenient because some fat sweaty lazy arsed good for nothing waster feels like he can't be bothered. [/RANT] Question about highlighted text => As I don't have a lathe do you think I can drill small holes in the skirt below the piston rings to remove weight? What's the purpose of the skirt below the wrist pin?
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#47
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Stretch, what diameter are these pistons? Hard to tell from photo, 90mm?
I think the first place would be the inside of the skirt area but you would need a lathe so the next best place (without a lathe) would be the wrist pin boss' where you could machine 0.080 (2mm) of the top. Then possibly start chipping away on the underside of the crown with a drill, several small divots. Do you have anyway of measuring the thickness of the crown?
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1995 E300 Diesel |
#48
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Hop on customfighters.com forum. They're bike guys but IIRC, a few have shops in your neck of the woods that will do stuff cheap. Also, a backwoods lathe can be made from a drill press and power sander pretty easily. I've turned down stuff when in a pinch that way. I wouldn't cross-drill any holes, but I might be persuaded to drill longways to remove weight.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#49
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do you have a dremel tool? you should be able to machine out the inner diameter of the skirt and remove 10 grams from the heavy ones.
I would not remove any material from the pin boss. but the skirt, and the crown are safe places IF they are thick.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#50
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The wall thickness is about 4mm at the thinnest points The under the recess on the inner side there's a thickness of about 4mm to the inwards bulge to the wrist pin recess - so I can't cut away too much there...
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#51
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I do have a dremel type thing - better actually a Proxon - I'm dead posh me... ...problem is there's not much I can really remove without making things paper thin. Here are some quick spread sheet calculations. 1) Drilling 4mm diameter holes in the wall (thickness is 4mm) 2) Hacking off the lower skirt bits I don't think this is a good idea though... ...20 grams is just too much to remove. 10 grams is pretty bad and I'm struggling to find enough metal for that...
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! Last edited by Stretch; 10-23-2013 at 03:44 PM. Reason: Messing about with numbers |
#52
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Do not remove the lower skirt. You could cause piston slap and / or scuffing wear in the bores. You could contour the skirt but that's not where I'd be working.
Look at the pin bosses. From 2:00 to 4:00 looks thinner than 8:00 to 10:00. There's a fair amount of unmachined area there to cause variance.
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When life gives you lemmings... make lemmingade. |
#53
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I would not feel comfortable removing any weight from those pistons. I'd try to find a better set. ARe the original pistons too far out of spec to reuse? I have re-used my benz pistons at least 75 % of the time when going through a motor. There are specs for measuring wear and determining if its acceptable.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#54
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You could tapper the inside hole of the wrist pin.
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76 240 D. Bought in 1998 for $25. 85 300D. Got it for free with a bad engine. ( Sold ) 60 Unimog 404. What was left of it, was given to me. Now powerd by 617A. 88 560 SEL. Bought without engine and trans. Now powerd by 617A. 67 250 SE. Cuope. For resto or sale. 64 220SE. For resto. |
#55
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Nooooooo. Never drill holes in pistons or remove skirts.
Remove material from the green areas _TOWARDS_ the crown, don't increase the diameter. The skirts keep the pistons square to the bore, this keeps the rings square to the cylinder wall resulting in good sealing and ring life. |
#56
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The problem with the green line area you've added to the picture is that on the areas where the there's a bulge for the wrist pin attachments there's only a 4mm thickness of material at that thinnest point. To remove (most of the) 20 grams of aluminium I need to remove to get the weight closer to the lightest piston a volume of about 0.75 cubic centimeters needs to be gone => this seems way too much material for the dimensions of the existing structure.
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#57
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The story with the pistons is this => I have a 1.8 litre M102. This has conical shaped piston crowned pistons. You need a head with a conical shape to match these pistons. Even here in Europe 1.8 litre heads seem to be rare - but there are many of the 2.0 litre head options available. I killed the 1.8 litre head by not reading the FSM properly - fitting the tensioner incorrectly and snapping the cam etc etc etc... The bore and stroke of the 1.8 and 2.0 M102 engines is the same (differences in swept and unswept volume are due to head and piston design) so you can swap out the 1.8 pistons with 2.0 pistons and fit a 2.0 head to convert a 1.8 to a 2.0... ...I have found a Carlsson never used ported and polished head for a 2.0 engine for not much money at all. With the cost of the four brand new 2.0 pistons (THAT SHOULD HAVE BEEN GOOD!!!!) I should be able to get a working engine for less money than the cost of machining and refurbishing a cylinder head. That was the plan - as usual there's no such thing as a hassle free cheap lunch... I don't think that will give me enough metal removal. 0.75 to 1 cc is a lot. I think 1project2many is right in saying that the only place to remove the metal is around the wrist pin bosses - I'm not sure if I have the gonads for that though...
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#58
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I spoke with my local engine builder (builds race engines for speedboat racing and has done heads up for me on a few occasions)
He didn't have the time to go into it too much but said if he was making a piston from scratch and it was to be 89mm then he would make the crown thickness 9mm and cut it back (for balancing purposes if needed) to 7mm. He would not advise going any thinner (on the crown) than 4.5mm. If you say the thickness of the crown is at 4mm in some spots already, then there really isn't going to be much you can shave from there. He has in the past machined off from "anywhere that is safe to do so - wrist pin boss's the inside of the skirt and the underside of the crown" If you were to speak with Nural, do you think they might exchange your set for a [better] mated set?
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1995 E300 Diesel |
#59
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What type of tensioner was it? The ratchet type that requires activation once it's installed or the hydraulic type. Please give us the heads up.
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1995 E300 Diesel |
#60
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If you cannot return or exchange these pistons, and they are unacceptable as-is, then they are junk. You spend only time to work on junk pistons and whether you install them or not, you gain valuable experience before you're done.
What 97 SL320 is referring to is the factory's balancing method. It's a single cut to save time and money. If you look at the difference in thickness of the pin boss between that machined area and the portion toward the center of the piston, it appears substantial. I wouldn't be afraid to continue the factory operation. I would still try to identify where the differences are between pistons before metal removal. Just out of curiousity, are the specifications you're citing for the maximum weight variation for the 1.8 or 2.0 liter engine? Are both engines subject to the same limits?
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When life gives you lemmings... make lemmingade. Last edited by 1project2many; 10-24-2013 at 07:32 AM. |
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