Hello. Does anyone have any tips to rebuilding worn valve seats in EW? I thought I had read an article here once but now can't find it. I was thinking of metal spraying them and re-cutting.
Normal inserts could not be put in because of the fixed head.
Also I was looking for a good technical article I had read as to why the crank assembly is prone to twisting in the EW. I think someone in USA or Canada had written it.
Hello,
It is wrong to assume that you cannot fit new valve seats to EW fixed heads. You can set up the head in a milling machine (the seats are at an angle, so you have to start with good new valve guides and some kind of a pilot pushed down in them so that you can clock with a dial gauge and centralize). I used a SERDI HD 100 valve seat machining centre for ease of machining (Please see the attached photo). Even if the seats are heavily pocketed and you have to machine the counterbore bigger than the valve plug thread diametre -- all is not lost as you can insert the newly made valve seat ring through the cylinder and then position it over the counterbore and, using a special press tool, hammer it in. The hammer is used because it allows you to hear by the change of noise when the seat is home. The seat must be polished with a nice radius for entry. Also I use American-made Seallock International Fluid-Weld polymer sealant to better transfer the heat and and to fill voids and to assist in pressing in. This stuff is not anaerobic and will withstand over 1000 degrees Centigrade! For EW I use 0.10 mm interference fit for the seat and I drive the seat in cold. Slightly chamfer the counterbore edges, so that they do not dig into the seat. Seat ring can be 7 mm in height and if you make the exhaust ring inner diametre 1 mm smaller and the intake valve seat inner diametre 1 mm bigger than the original diametre, your engine will breathe better! As for the seat material I use Chrome-Moly-Vanadium steel -- it will last for ever even if using modern lead-free petrol. After fitting the seat must be machined according to the valve -- best way is to use Neway cutters with 1 degree interference angle, i.e 46 degree seat cutter.
I would strongly recommend to avoid flame powder spraying in this position -- inside the combustion chamber, if you do not know well what you are doing, as the cylinder will distort and the working can get very tough with all that heat and poor visibility inside -- sometimes it is like trying to blow into a bottle! The torch will heat up and will start backfiring. Also there is the danger of getting powder onto the plug thread and with all that heat this powder may melt and clog the thread. You can of course protect the thread with a strip of stainless steel, but that is quite a difficult task as the strip will try to get welded to the head, etc. After flame spraying it is most important to cool the cylinder or head properly -- for best results you can use Verniculate powder -- just dig your cylinder in it and it will dissipate the heat evenly for 8 hours! I have also attached a photo of a 1913 Indian cylinder head Resurrection work where flame powder spraying was the only feasible alternative, so that you can see what can be done with flame powder spraying. Should there be any more questions regarding fitting new seats, or flame powder spraying please do not hesitate to ask.
Good luck with your seats.
This information is from Latvia...
LATDOUGNUT
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