Στο θεμα μου τωρα με το τι εδρες και βαλβιδες πρεπει να μπουν για να γινει μια σωστη δουλεια.
Ο ενας μου ειπε βαζουμε ξανα κανονικες εδρες και βαλβιδες,ο αλλος μου ειπε στελιτες και τιτανια ειναι τριχες και βαζουμε μονο εδρες ατσαλινες(240 ευρω οι εδρες!),καποτε ειχα διαβασει για στελιτη και ξαναβρηκα το αρθρο,υπαρχει κανεις που κανει αυτη την δουλεα εδω Ελλαδα και βαζει εδρες και βαλβιδες απο στελιτη?
http://www.sbintl.com/tech_library/arti ... rsions.pdf
Απο αυτα που διαβασα καταλαβα οτι δεν παιζουν ρολο μονο τα υλικα που θα βαλουμε στιε εσδρες και βαλβιδες αλλα χρειαζονται και διαφορες τεχνικες απο τον μηχανουργο για να γινει σωστη η δουλεια για να καψουμε σωστα και χωρις μελοντικα προβληματα το lpg,πρωτα λεει οποσδοιποτε βαζουμε πιο φαρδιες εδρες απο τις μαμα για καλυτερο διαμοιρασμο της θερμοτητας ,μετα λεει για το υλικο των βαλβιδων και εδρων και παλι στο τελος λεει οτι παρολου και αν γινουν ολες αυτες οι εργασιες παλι μπορει να γινει η στραβη αν δεν πειραξουμε το αβανς για να καιει υγραεριο(αληθειαι πηραζει κανεις εγκαταστατης το αβανς ?) και να εχουμε σωστα μιγματα!
"While these are
techniques to aid the rebuilder, the parts manufacturers can do their
part to help the valves and seats survive. One action taken is to
upgrade the materials the valves and seats are made from. Valves for
LPG engines are specifically designed to withstand the extra wear
experienced with the use of LPG fuels. The valve faces need to be
protected as do the seat contact surfaces. In the case of valves, the
addition of hard facing materials, usually Stellites, is considered
essential in preventing valve failures. In some cases the valve head can
be made from a nickel based super alloy such as Inconel. This alloy
flexes less than regular exhaust material thus preventing wear due to
valve head bending. In some cases, 454 GM for example, both of these
techniques are required to provide acceptable service life. The valve
can also be internally cooled with sodium if required. The valve seat in
the head also needs some attention. If the head was not designed to
run on LPG, the valve seats need to be inserted with a material
specifically designed for gaseous fuel use. These seats are very hard
even at operating temperatures. They are generally made with a high
Nickel and/or Stellite content to withstand the corrosive and abrasive
action present in LPG fueled engines.
It is often after sales service that can make the difference to engine
survival. When an engine has been converted to LPG use and the
cylinder head has been built specifically for the fuel, it can still fail
without attention to both the ignition system and the fuel mixture. The
distributor must be recurved to provide total advance of 36 at
1000 RPM (15" of vacuum) and total advance of 42 at 3000 RPM.
Initial timing can be advanced about 10% but if this is done, an equal
amount must be removed from the total advance curve. The fuel
delivery system is also important. Most LPG systems require a 2%
oxygen exhaust content to ensure adequate cooling in the combustion
chamber. Unlike gasoline engines, a rich LPG mixture overheats the
valves and seats causing seat recession. The only way to ensure the
correct fuel mixture is to use an exhaust gas analyzer.




