[Fot] dimensioned drawing for stock TR4 exhaust valve needed

[Tim Murphy]

I am having new exhaust valves made with Manley XH-428 stainless steel, a
super stainless.  It is good for exhaust gas temperatures up to 1350
degrees.  On tearing the engine down for a rebuild we found that the exhaust
valves were severely "dished" on the seats, we think from the high heat.
The valves were only contacting the seat in a very narrow (about 0.020) line
at the end of the seat width.  We did have good power but the compression
test and especially the leak down test showed there to be some problem.  At
WOT we run between 1200 to 1300 degrees.  I have to supply Manley with the
dimensions and angle of the valves I need.  It is a bit difficult to measure
accurately the back cut angle and width I'm not sure if the corners should
be sharp, broken of have a corner radius.

 

The workshop Manual shows a seat angle of 45 degrees and a seat width of
0.060 with a head diameter of 1.438 inches (36.51 mm).  I don't know what
the margin should be.  I also have to give them the groove type, height,
depth and radius for the keepers.

 

Any help and/or suggestions for what would make a better racing valve would
be appreciated.  Note: Manley has pre-made "blanks" out of various super
stainless already made up. This makes the cost of the valves realistic.  I
found one part number that can be make into a TR4 exhaust valve.

 

Tim and Ryan Murphy

1961 TR4 #317 BRG

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/fot/attachments/20150216/4df14745/attachment.htm>