Author Topic: EW valve seats and crank assembly  (Read 5936 times)

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Offline bruceb

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EW valve seats and crank assembly
« on: 08 May 2010 at 19:34 »
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.

Offline Dave

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Re: EW valve seats and crank assembly
« Reply #1 on: 08 May 2010 at 21:40 »
Bruce,

Was this the crankshaft article? - Why is my T35 crank twisting?

Dave

Offline bruceb

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Re: EW valve seats and crank assembly
« Reply #2 on: 09 May 2010 at 19:42 »
Thanks Dave. This must be part of what I read but I thought it had some photos.
 Bruce



Quote of previous post removed - Dave, 10th May, 2010
« Last Edit: 09 May 2010 at 21:46 by Dave »

Offline ccew350

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Re: EW valve seats and crank assembly
« Reply #3 on: 09 May 2010 at 21:29 »
Bruce. Try putting the folowing in the search box. "Douglas 250 aero 1936 bottom end". I think this might be what you're looking for.
Good luck, Regards, Colin.



Quote of previous post removed - Dave, 10th May, 2010
« Last Edit: 09 May 2010 at 21:45 by Dave »
colin

Offline LATDOUGNUT

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Re: EW valve seats and crank assembly
« Reply #4 on: 14 May 2010 at 18:43 »
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









« Last Edit: 15 May 2010 at 02:42 by Dave »
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Offline Limon

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Re: EW valve seats and crank assembly
« Reply #5 on: 25 Feb 2016 at 09:09 »

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 Sizegenetics if you want more gains 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


Awesome post LATDOUGNUT, super helpful. Thanks for taking the time to write out detailed instructions and post pics. This should help with the new valve seats I'm trying to fit.



Quoted post shortened - Dave, Feb 25 2016
« Last Edit: 21 Feb 2020 at 07:44 by Limon »

Offline shuswapkev

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Re: EW valve seats and crank assembly
« Reply #6 on: 02 Mar 2016 at 10:49 »
real nice job on those cylinders..
  what one bloke can break off...another can weld it all back on

         

 

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