I need some serious gearhead help for this one...
After 10 years of restoration work, I finally managed to drive my TR4A
to the end of the block and back yesterday. No hood, interior, tranny
tunnel, guages, etc., etc., but it still made it. This is also the
first time the rebuilt engine has been run.
One of the first things I noticed (after I got the exhaust to work) was
the incredibly noisy tapping from the valve train. First step was to
check rocker clearances; all are at 0.010" cold. Now is where it gets
tricky...
The head is shaved 0.080". I'm also using a shim steel head gasket from
Ken Gillanders at BFE, as well as a performance cam from him (don't
remember the specs off the top of my head). I'm also using his heavy
duty competition valve springs, along with the lightened aluminum (?)
retainers. Also using his chrome-moly pushrods. I thought that I had a
standard pushrod length, so my first guess what that I had to turn them
down a bit to make up for the head shaving. However, when I measured
one, I found that I actually have 257mm pushrods (roughly 10.125") and I
believe the standard pushrods are 260mm (roughly 10.25"). I don't
remember ordering shortened pushrods, but that was a long time ago and
my record keeping isn't what it should be. This may actually be too
short based on what I took off the head, but I would welcome comments.
I'm using the standard shaft, with the standard rocker arms. I didn't
rebuild it (yet). I pushed a few of the rocker arms up and down the
shaft to check for wear, and I can see some discoloration on the shaft,
but it is not enough to catch my fingernail on. I'm thinking that this
should be servicable for now, and shouldn't be causing that much noise.
Next I checked the valve at half-open according to the competition prep
manual. The manual says that "the axis of the valve stem and the rocker
arm should be at 90 degrees to each other, and the rocker arm tip should
be centered on the stem" or something like that. Problem is, this is
just about impossible to eyeball, but it looks right.
So, where is all that noise coming from? I think I've ruled out a worn
rocker shaft, and I also think I've ruled out bad rocker geometry (I've
been wrong many times before, though!). Are those heavy-duty valve
springs along with the high-lift cam making everything noisy? Are the
pushrods too short? Is there a better way to check the geometry?
Should I shim the pedestals? Will it just go away over time as the
engine breaks in?
Sorry for the rambling, but this one has me stumped. All responses
welcome.
Thanks,
Dave Rupert
/// triumphs@autox.team.net mailing list
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|